M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => General Topics => Topic started by: Cobra Jet on May 06, 2008, 10:56:25 AM
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I was just curious as to how many of you w/o chips are running 87 octane w/ no issues? I read some older threads and it seemed that some folks do run 87 octane with no adverse effects.
Are there any pros/cons to running 87 octane as opposed to 91 on a daily driven, well maintained vehicle that only sees normal use highway speeds?
I know if running a chip (Mark D., etc) that one would have to use 91 octane (or better) and of course if having a forced induction application 91+ is also the fuel to use.
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I'm running 91 but if it's overkill I'd love to know. 4.25/gal sucks
I can only get 87, 89 and 91 here.
Should i run 89 and see how it goes? Our cars have no knock protection so I'm cautious.
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I have an airport 2 miles up the road from me where we can buy 103 octane fuel (not e85 ethanol). other than that 93 is the highest I have seen around my way.
I am personally running 93 octane in my 318is, however, I do not use it as my daily so I can afford 93 from time to time. Car is bone stock right now. I did not have any issues at all. Well before my block exploded, I had no issues with 93 octane. But that wasnt because of my fuel. That was because of my piston slap.
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I run 93 ,sometimes 91 . Never tried 87 .
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I use 87 when the air temp is below 70f, 89 above 70f. With cold air intake I've been able to use 87 octane all the way up 85f. It hasn't been hotter than that yet but we'll see at what temperature it will start to ping again. Last tank was 31.5mpg, mostly short trips.
With a completely stock intake, air temperature inside the airbox can spike up to 40f above ambient. Try it. Take the outside temperature sensor and stick it inside the airbox.
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I've read using 87 can result in poor performance and low mpg. I use 87 on my car stock no mods aside the COP, exhaust, eliminated PS and K&N filter. I have installed a device that allows me to use the 87 and still feels like I am running high ocatin gas and get 26 mpg for mix driving and 30-32 for highway. This is my daily driver and high rev at 4 in between gears.
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I've been using 87 on both of my 18's and I get 30/31 MPG. About the only thing going on right now with mine is that the Cat is clogging up (I still get around 31 though). I only am running a K&N conical, and the car came with a generic aftermarket muffler. I haven't noticed ANYTHING as far as knocking. I am also using Iridium plugs (could be that the plugs are burning the fuel hot enough... dunno), so that could be why.
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I have installed a device that allows me to use the 87 and still feels like I am running high ocatin gas and get 26 mpg for mix driving and 30-32 for highway.
Don't tease me like that. What is this device?
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maybe I'll move down to 89 and see how it does.
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I run 93 only, my mods are chip, intake, pulstar plugs, resistorless leads, and a little tuning by me. I tried to run 87 before my mods and my little "Natascha" knocked and pinged oh! it was ungodly. There is a Circle K around the block from me. They have 100 Octane. Natascha runs soooo! nice. And the smell. MMMMM! racing fuel smells soooo! nice. Higher Octane fuel permits less carbon build up. The fuel burns hotter which burns the carbon. Lower octane does not. Once in a while you should add an octane booster to help clean out the carbon build up.
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With 10.1 compression I would not run 87. It's more fun to drive with 93 or + anyway. Well worth the few extra $$ IMOHO. :D
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With 10.1 compression I would not run 87. It's more fun to drive with 93 or + anyway.
Why?
I mean, others have used 87 octane w/o any detrimental affects - meaning those that are using their vehicles normally - not those who race away from every stop light and redline the vehicle through every gear...
It seems as though running 87 octane is pretty safe - and due to the current fuel costs for all grades of fuel, especially 91+ octane, using 87 can be a savings to those who daily drive their 318 and for those who travel an extensive amount of miles per day.
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I use 89 octane, my gas milage is fart so far. For some odd reason I was getting better gas milage on my m20, it doesn't make any sense. I think it may be my fuel filter. I'm going to try 91 and see if it makes a difference, in milage i'll get back to yall if theres a difference. This should mean a lot to everyone since gas prices are sky high :eek:
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Interesting stuff
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I use 89 octane and am wondering myself if this is good enough? I can't seriously give any advice/info on how much of a difference it makes because:
1) After the tickets I got, my 318is sits in the driveway
2) I am on my second tank of gas since February/March? (whichever month I filled it up in), still on F
3) My first tank of gas was an unknown octane (bought it with full tank of gas)
4) I can't say I know much about gas and octanes anyway. All I know is the higher the octane, the higher the $$ :mad:
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I usually run 89, and occasionally a tank of 91. I can locally get 87,89,91,93,and 100 at the pumps. If I go inside the gas station I can get 110 unleaded. Boost on 10:1 compression ftw! :D
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RON ratings are only an indication of the fuels ability to resist 'knock' (i.e. detonation, pinking etc). Power gain from using such fuels is pretty much non existant.
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Without a chip, I can tell when I have poor quality 91 in the car. I lose mileage and performance. I only run 91 from a better rated gas company and 93 from others unless I am in a pinch.
The manual states 91 octane.
110 is overkill and you are actually doing damage to your cat by doing that.
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RON ratings are only an indication of the fuels ability to resist 'knock' (i.e. detonation, pinking etc). Power gain from using such fuels is pretty much non existant.
It depends on how you look at it. A simple statement like that is incorrect due to the number of assumptions that can be made from it.
RON is actually burn speed. Higher octane burns slower. A slower burning fuel may not fully fully burn sending raw fuel into the catalytic converter where it is burned off. Too much and it destroys the cat. A lower octane gas in a car detonates or burns too fast, this can make you lose lots of power and damage a piston or valve or bearing.
Power benefit depends on how you look at it. If your car is timed for a slower burning fuel (like 91) and you put 87 in there, you can lose a lot of power. However putting 91 in a car meant for 87 does little.
I had a Toyota that would get 5-6 mpg better with premium. When I figured out the mileage vs fuel cost, it was cheaper to run premium by $2 per tank.
Bottom line, run close to what the manufacturer tells you. You can vary a little, try tracking mileage to see what is giving you the best burn. Whichever gives you the best mileage is what the engine prefers. This will be close to what the manufacturer recommends usually.
I would not try 87 in a car meant for 91, that is too large of a jump. 89 will probably the lowest you should go.
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Oh im not running 110 in my car. I run 89 or 91 usually. But its nice to know that I could boost the m42 on stock compression :D. If im willing to pay about 9-10$ a gal....
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I filled up a year ago and am still burning it off.
Filled up the day the head gave out!
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^ Fuel has a shelf life. All dependant on the quality of the fuel really, depends where you got it from and what additives they use.
RON is actually burn speed.
Sorry, it isnt. Burn speed is known as the Flame Kernel, and its a different matter entirely. RON means Reasearch Ocatne Number, and it denotes the petrols knock resistance. For lack of a better source, check wikipedia (http://en.wikipedia.org/wiki/Octane_rating) if you think im wrong ;)
Petrol itself is a very good knock-inhibitor. Stripped bare of any additives, the actual chemical formula of petrol does well agianst fighting off knock. Once we throw additives like Octanes [and therefore 'octane ratings'] into the mix, then we begin to increase the fuels knock capabilities.
Dont confuse the term 'octane' to how much 'oxygen' that you think is in the fuel [which people associate with providing a cleaner, more powerful combustion] like many do. Octane has the chemical formula C8H18 (Carbon8Hydrogen8). Iso-octane is a branched hydrocarbon, and is used to define a fuel’s octane rating. It has excellent anti-knock ratings and is highly desirable in petrol - it isnt a form of oxygen in any sense of the word; and thus has no power-increasing characteristics.
Also, as Octane ratings are all about knock-resistance I should mention that fuel injected cars need a way of sensing/detecting knock in the 1st place...hence knock sensors:
I had a Toyota that would get 5-6 mpg better with premium. When I figured out the mileage vs fuel cost, it was cheaper to run premium by $2 per tank.
Seeing as pretty much every Toyota comes with knock sensors, youve just proven my point ;) Your Toyota advnaced its ignition to take advantage of the higher anti-knock capabilities of the fuel. Which, in-turn, gave you better, more cleaner ignition = fuel savings...and a tincy-tiny powah increase.
BTW people, the M42's dont have knock sensor...so all of this is kind of pointless. Without knock sensors, 'premium' fuel is just a waste of money.
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Seeing as pretty much every Toyota comes with knock sensors, youve just proven my point ;) Your Toyota advnaced its ignition to take advantage of the higher anti-knock capabilities of the fuel. Which, in-turn, gave you better, more cleaner ignition = fuel savings...and a tincy-tiny powah increase.
BTW people, the M42's dont have knock sensor...so all of this is kind of pointless. Without knock sensors, 'premium' fuel is just a waste of money.
Timing advance on a 1979 Toyota, I don't think so.
If premium was not necessary, BMW would not have put it in the manual that it is required. There is at least one or 2 people on this forum who have had their engines fail by using incorrect fuel.
Go ahead if you want, personally I am not going to risk it to save what amounts to an extra buck or two per tank, especially when I can feel a difference in how the car runs. More power or not, the car does run better.
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Interesting replies...
I started this thread because prior to my 91 318ic going down on a non-start issue (that thread is in the appropriate section on here) - I was successfully running 87 octane with NO issues what so ever... Meaning, I did not have or experience any pinging, no knocking, no pre-ignition, no drivability issues, etc etc etc. As a matter of fact, out of a completely full tank of 87 octane gas, I was able to go 384 miles out of my last tank - no BS. I've read on other forums about other BMW owners of E30's, both 318's & 325's also using 87 octane with no issues at all.
Now, I don't flog on the car at all - meaning, I don't jump stop lights, I don't try to race others on the highway, I don't speed shift, I don't do WOT runs up and down the streets, etc. I use the car in a normal manner - driving to & from work, shifting it right before 3k, running errands, etc. My daily commute to & from work, total round trip is 114 miles - 5 days a week.
Sure, the owner's manual may state to run "XX" octane - however, just because the manual states to run "XX" octane does not mean the car will not run on lower (or higher) octane fuels. Heck, I even run 87 octane in my Cobra - when the manual for that also states to use 91 (or better) octane - that car runs flawlessly as well.
Understandably so - if one has a highly modified engine, be it a naturally aspirated engine that has been radically bored out, heads, intake, cam, exhaust, etc., OR if running a forced induction vehicle (supercharger or turbo), OR if the vehicle has been "chipped" then surely I can see that such a vehicle would HAVE to be on a strict higher octane "diet". But, if all you are doing is driving your 318/M42 to and from in a normal manner, the car will get nearly the same mileage (maybe even better) on 87 octane AND it will operate, idle, drive & run perfectly fine.
I previously filled the tank 3x now w/ 87 octane - each end result was 378, 381 & 384... and the gas gauge needle was just about resting on the "R" - the gas gauge low level light never illuminated for any of those prior fills... (the low level light DOES work, because when I first bought the car it only had a little gas in it and I ran it down to the point of when that light kicked on).
I had read online that when or if the low level fuel indicator light does come on in a 318/M42, the driver/operator has about another 12 miles to go before the tank is COMPLETELY EMPTY (or in danger of running out of gas). If I were to run the car to that point on the last result of 384 miles, I realistically could have tallied up 396 miles on a tank of 87 octane... That's damn close to 400 miles on a single tank of gas - good or bad?
Oh and one more thing - don't go busting my chops about running the car low on gas - I've heard all of the myths, stories, threads, etc as to "sucking up tank debris, etc" if running the tank or pump below 1/4 tank... I've run every car I've ever had down to nearly the "last drop" and I've never once had ANY vehicle EVER burn up a fuel pump, suck shit into the engine, etc - NEVER. Let me also add there is NO WAY the fuel pump COULD suck up anything into the engine if running the tank low because: 1) The fuel pump has an extremely fine mesh screen (or commonly known as a sock) on the bottom of the pump which prevents ANY debris from getting sucked up into the pump OR fuel lines and 2) the fuel filter also filters out any impurities and/or mirco particles that *might* get past the fuel pump's screen... Don't believe the hype - sure it's ok to take precautions, but seriously, running the tank down to 1/4 or less is NOT going to hurt anything (IMO).
Now, back to 87 octane - for those running a non-modified M42 - fill up with one tank full of 87 and drive the car normally - post back here w/ your results/observations, etc. If you're driving style is that of Mario Andretti, don't even bother...
Now, there are numerous things that COULD and CAN affect fuel consumption:
1) driving style
2) duration of travel
3) highway or local travel
4) preventive maintanence of engine/vehicle (checking things BEFORE they become inoperable)
5) tire psi inflation
6) regular maintenance of engine or driveline (oil changes, fuel filter, air filter, pcv valve, injector cleaner, tire rotation, brake wear, wheel/hub bearing wear, tranny fluid changes, rear diff fluid changes, etc)
7) driving w/ windows open (changes aerodynamics of vehicle)
8) driving w/ A/C on
9) speed limit of vehicle over a prolonged traveled distance
10) geographic location (above or below sea level)
I'm glad to see the above responses, because I was just curious to see how the thread would progress knowing that I myself do run the 318ic on 87 octane (and that others have or do as well).
Keep the conversation going!
:)
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There is at least one or 2 people on this forum who have had their engines fail by using incorrect fuel.
What members had engines fail due to FUEL issues?? I personally do not see how using any other octane other than what is stated in the BMW user Manual that by doing such would cause a catastrophic engine failure. There had to be other issues that led up to the engine failure.
What are the other facts based on those failures? What was the long term maintenance history of each engine prior to failure? How many miles on each? Etc....
If the cylinders were being washed down (dumping fuel), sure, this would eventually cause a failure due to washing out the bearings as well (dilluting the normal oil lubicration properties) - however, that would not be caused by running a lower octane fuel as there are many other factors that would cause cylinder wash out...
Where are these threads - as I want to read them.
Like I said, I've seen other threads or posts not only on this site but other BMW sites where folks have successfully used 87 octane w/ no adverse effects.
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I have an aftermarket chip so I always use premium. But I would use premium even with the stock chip.
The reality is that you're probably not going to cause major engine damage if you drive mildly and use a less-than-recommended octane. (Let's face it; you're much more likely to have to deal with a major engine repair due to wear of the M42's timing components or having a bolt sucked out of the upper oil pan.)
But the reality is also that long term you're going to see driveability problems due to things like excessive carbon buildup on the valves or a failed catalytic converter.
These days, I spend too much time at work to work on my car as much as I'd like. So I want to eliminate as many problems as I can before they begin. I've also cut back my driving considerably over the past several years and am now down to about 8-9k miles/year. Cutting your miles traveled in half (or even by a quarter) will save a lot more money than buying lower octane fuel.
Higher gas prices are here to stay and for all but the rich we're going to be forced to make some major changes in our driving habits as prices continue to rise.
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Timing advance on a 1979 Toyota, I don't think so.
If premium was not necessary, BMW would not have put it in the manual that it is required. There is at least one or 2 people on this forum who have had their engines fail by using incorrect fuel.
Go ahead if you want, personally I am not going to risk it to save what amounts to an extra buck or two per tank, especially when I can feel a difference in how the car runs. More power or not, the car does run better.
I wouldn't indiscriminately run this engine on 87 octane when the intake temperature varies between 122-158f while the ambient temperature is 64-82f.
(http://farm4.static.flickr.com/3104/2451663089_638bf16fe5_o.jpg)
BMW specifies 91 octane because the engine was designed with an extremely hot air intake. Fix the intake and you can safely use 87 octane.
http://www.m42club.com/forums/showthread.php?t=5561
Anybody can use the outside temp sensor to check the temp inside the airbox.
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Now, I don't flog on the car at all - meaning, I don't jump stop lights, I don't try to race others on the highway, I don't speed shift, I don't do WOT runs up and down the streets, etc. I use the car in a normal manner - driving to & from work, shifting it right before 3k, running errands, etc. My daily commute to & from work, total round trip is 114 miles - 5 days a week.
Sure, the owner's manual may state to run "XX" octane - however, just because the manual states to run "XX" octane does not mean the car will not run on lower (or higher) octane fuels. Heck, I even run 87 octane in my Cobra - when the manual for that also states to use 91 (or better) octane - that car runs flawlessly as well.
If you read your manual you will find your way of driving your 318 is not good for it. The manual tells you you need to get it up above 3k regularly. In fact they give a ratio of how much above and below you should spend.
These cars were meant to be flogged, not granny shifted.
As I said, am sure you can get away with it, but it is not worth it to me. Too much risk.
I had read online that when or if the low level fuel indicator light does come on in a 318/M42, the driver/operator has about another 12 miles to go before the tank is COMPLETELY EMPTY (or in danger of running out of gas). If I were to run the car to that point on the last result of 384 miles, I realistically could have tallied up 396 miles on a tank of 87 octane... That's damn close to 400 miles on a single tank of gas - good or bad?
I have no idea about the 12 miles, but if that were true, I would have just been on fumes. Most cars with a light like that come on around 1-3 gallons left.
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What members had engines fail due to FUEL issues?? I personally do not see how using any other octane other than what is stated in the BMW user Manual that by doing such would cause a catastrophic engine failure. There had to be other issues that led up to the engine failure.
Not sure who it was, but the rod bearings took a beating. Apparently nothing else was too bad. Normally these engines do not go through bearings.
Just because you do not hear pre-ignition does not mean it does not exist. By the time you hear and notice it, it is is pretty bad.
Maybe one of them will chime in.
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Been running 89 AKI in my stock motor for the past few hundred miles and haven't noticed any pinging or change in performance.
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I have to say, sheepdog has given alot of good advice in the past, its hard to go against what he says!
I give you a +1 on da 91 sheepdogg!
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If you read your manual you will find your way of driving your 318 is not good for it. The manual tells you you need to get it up above 3k regularly. In fact they give a ratio of how much above and below you should spend.
These cars were meant to be flogged, not granny shifted.
I did not know that. I think I still have the manual that came with the car, ill have to read it
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Too many people these days take forums too literally. Stop being such NetSperts!
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Dont talk trash about the intratubes.
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(http://i128.photobucket.com/albums/p180/metallica2k1/internet_serious_business.jpg)
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Cobra Jet. your are right there are many different things that can affect fuel consumption. You have to take in consideration of those factors you posted and more you probably can't think of. Later.
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Actually, despite the higher cost of fuel, the difference between 87 and 91 is still only .20 per gallon. Really, $2 is good peace of mind to follow the manual.
Now if it was +.50 more then i'd start to think about it more.
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I run 87 all the time. No problems but I live and drive in Denver. Lower Comp. ratio you know less air at 6000 ft.
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I only put Chevron 92 octane in my car because it says right on the gas door PREMIUM ONLY. Lower grade fuel doesnt not detonate as pure those causing "massive" wear not intended by BMW. I wouldn't use 87 octane unless you feel your cars engine is worth 2 dollars per tank. Run 92 octane or you are crazy. Better explosions are better its as simple as that.
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Better explosions are better
:)
Simple enough.
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Cobra,
Running the tank that low all the time has a tendency to burn up the pump quicker since the fuel cools the pump.
As far as 91 octane goes, I'd stick with the factory recommended grade or higher. The difference in price is neglible.
And I have to agree with sheepdog...just cause you don't hear the detonation doesn't mean it isn't happening. Why dirty up that nice clean engine with cheap fuel?
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To each his own I guess. When you realize that the stock intake sucks in air at 158f it becomes pretty obvious why bmw requires 91 octane or better for this engine. There is nothing special about a 10:1 CR engine using 87 octane. My 10.7:1 CR volvo has been for the last 260k miles. Fix the intake problem and you can use 87 octane at all temperatures.
Also please don't tell me in not going to hear ping or knock. I've seen the difference octane can make for this engine depending on air temperature, altitude and load.
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Lower grade fuel doesnt not detonate as pure those causing "massive" wear not intended by BMW.
Care to elaborate? You lost me on this sentence.
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Care to elaborate? You lost me on this sentence.
Basically what I was trying to say if you run crappy gas you increase the wear on your internals..its not massive but would you not change your oil because it saves you 2 dollars?
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Basically what I was trying to say if you run crappy gas you increase the wear on your internals..its not massive but would you not change your oil because it saves you 2 dollars?
???????
Do you have any evidence whatsoever to suggest that "crappy gas" increases engine wear?
the difference between 91 and 87 octane around here is 30 cents per gallon. I drive 12k miles per year at 30 mpg average. So that's an extra $120 of unneccesary cost per year to drive a $1000 car. Hmmmm I don't think so. How many decades do you plan to own your car exactly?
I'm completely lost in the second half of your statement.
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Basically what I was trying to say if you run crappy gas you increase the wear on your internals..its not massive but would you not change your oil because it saves you 2 dollars?
I personally don't think lower RON value means the gas is crappy. Afterall, the purpose of RON value has nothing to do with fuel quality, higher value only means the fuel is more resistance against detonation.
However, manufacturers may include addictives inside fuels with higher RON values. Take my country for eg. Shell offers 92, 95, 98 and V-power (quoted value is 100). V-power is quoted as having additives added to reduce friction and clean intake valves and combustion chambers. Such additives was not quoted on lower grade fuels. 92 and 95 petrol do not have any performance enhancing additives quoted.
Thus I think the main difference is not due to the quality of the petrol but rather the additional chemicals added into the petrol to your engine perform better.
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original CNN link: http://money.cnn.com/2008/05/12/autos/ways_to_not_save_gas/index.htm?postversion=2008051315
Article copied & pasted from link:
6 gas-saving myths
Sure you want to save gas, but there's a lot of bad advice on how to do it. Some of it makes no difference, and some of it can wind up costing you.
By Peter Valdes-Dapena, CNNMoney.com staff writer
Last Updated: May 13, 2008: 3:11 PM EDT
NEW YORK (CNNMoney.com) -- With gasoline prices hitting record levels, it seems everyone has a tip on how to save fuel. Much of the advice is well-intentioned, but in the end, much of it won't lower your gas bill.
Here's a look at a few misconceptions:
#1. Fill your tank in the morning
You may have heard that it's best to fill your gas tank in the early morning while the fuel is cold. The theory goes that fluids are more dense at lower temperatures, so a gallon of cold gas actually has more gas molecules than a gallon of warmer gas.
But the temperature of the gasoline as it comes out of the nozzle varies little during the course of the day, according to Consumer Reports, so there's little, if any, benefit, to getting up early to pump gas.
#2. Change your air filter
Maintaining your car is important, but a clean air filter isn't going to save you any gas. Modern engines have computer sensors that automatically adjust the fuel-air mixture as an increasingly clogged air filter chokes off the engine's air supply.
While engine power will decrease slightly as the air filter becomes clogged, a lack of performance or an increase in fuel consumption will be negligible, Consumer Reports says.
#3. Use premium fuel
With prices already over $4.00 a gallon, premium gasoline is a hard sell these days. But a lot of drivers think because their owners' manual recommends premium, they'll get better fuel economy if they stick with it. Really, they're paying more money for nothing.
Even cars for which premium is recommended won't suffer with regular fuel. Modern engine technology comes to the rescue again. When sensors detect regular instead of premium fuel, the system automatically adjusts spark plug timing. The result is a slight reduction in peak horsepower - really, you'll never notice - but no reduction in fuel economy.
#4. Pump up your tires
Proper tire inflation is important for a number of reasons. Under-inflated tires are bad for handling and can even cause a crash. Improper tire inflation also causes tires to wear out faster and to heat up more, which could trigger a dangerous high-speed blow-out.
According to on-the-road driving tests by both Consumer Reports and auto information site Edmunds.com, underinflated tires reduce fuel economy, so proper inflation is key.
But you should never over-inflate your tires. They'll get you slightly better fuel economy because there will be less tread touching the road, reducing friction. But that means less grip for braking and turning. The added risk of a crash isn't worth the extra mile a gallon you might gain.
#5. To A/C or not A/C
There's no question air-conditioning makes extra work for the engine, increasing fuel use. But car air conditioners are much more efficient today than they used to be. In around-town driving, using the A/C will drop fuel economy by about a mile a gallon.
Meanwhile, driving at higher speeds with the windows down greatly increases aerodynamic drag. As speed increases, drag becomes more of an issue, making A/C use the more efficient choice at high speeds.
At most speeds and in most vehicles, A/C use drains slightly more fuel than driving with the windows down, contends David Champion, head of auto testing for Consumer Reports. "My final take on is that it's very close," says Phil Reed, consumer advice editor for Edmunds.com. "It's hard to measure the difference and every vehicle is different."
The best choice - if temperature and humidity allow - is to keep the windows rolled up and to turn the A/C compressor off. You can keep the fans running to blow in air from the outside, but your car will be as aerodynamic as possible while still letting you breathe. You will save gas, but the fuel economy improvement will be slight.
#6. Bolt-ons and pour-ins
Before you buy a device that's supposed to make your car more fuel-efficient or pour in an allegedly gas-saving additive, ask yourself this: Don't you think oil and car companies aren't doing everything they can to beat their competitors?
If BP (BP) could add something to its gasoline that made cars go farther on a gallon, cars would be lining up at the company's pumps. Sure, people would burn their fuel-saving BP gas more slowly, but then they'd drive right past rivals' gas stations to come back to BP for more. BP stations could even charge more for their gas and still sell tons of the stuff.
So if there really was an additive that made gas burn up more slowly, it wouldn't be sold over the Internet one bottle at a time.
Likewise, car companies are already spending big bucks to increase fuel mileage. If General Motors could make its cars go significantly farther on a gallon simply by putting a device into the fuel line, don't think for a second it wouldn't be doing that. GM's car sales would go through the roof.
"There are a number of these gas-saving devices that are generally useless," says Champion.
But drivers who try them will swear they work. In reality, it's probably an automotive placebo effect, says Reed. Buy one of these devices or additives, and you're like to pay extreme attention to your fuel economy and how you drive.
Of course it can't hurt to keep a close eye on your driving habits -- and what kind of car you drive. In the end, that can make the most difference in saving gas.
~~~
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The reason I run chevron premium is because its not like that shell trash. Chev gas is better because it doesnt sit in the tank for a week. Its cleaner and thus provides better explosions. Riddle me this. My buddy has an evo x and chipped it to 320hp at the wheels. Now should he run regular? No? Should he not use synthetic? No! I get what your saying cobra. If you want to save money like a goldstein run regular and drive like a grandma but I believe you should drive a non turbo base model volvo. I feel bad for anyone who uses crappy oil and crappy gas
Ps. His all aluminum engine is only 9:1 so certainly he doesnt need 92 or better. Hmmmm his air intake is in the middle of the hood. Must be cold! As cold as an sti's intercooler
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#3. Use premium fuel
With prices already over $4.00 a gallon, premium gasoline is a hard sell these days. But a lot of drivers think because their owners' manual recommends premium, they'll get better fuel economy if they stick with it. Really, they're paying more money for nothing.
Even cars for which premium is recommended won't suffer with regular fuel. Modern engine technology comes to the rescue again. When sensors detect regular instead of premium fuel, the system automatically adjusts spark plug timing. The result is a slight reduction in peak horsepower - really, you'll never notice - but no reduction in fuel economy.
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I'm totally with you here.... BUT.... our cars do not have knock sensors and cannot retard timing when pre-detonation is sensed. Sorry, if we drove the more modern M44 we'd be OK. E30 M42, no such luck.
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Dude, you do know that's a turbo right? 9:1 comp with turbo to 320hp is pushing over 1 bar pressure. I'm with you on sticking with 91 to be safest in the M42 but that is the worst comparison/argument I've ever heard! :D
Nothing personal though.
And oh yeah, you can leave out the racial slurs, keep it civil.
The reason I run chevron premium is because its not like that shell trash. Chev gas is better because it doesnt sit in the tank for a week. Its cleaner and thus provides better explosions. Riddle me this. My buddy has an evo x and chipped it to 320hp at the wheels. Now should he run regular? No? Should he not use synthetic? No! I get what your saying cobra. If you want to save money like a goldstein run regular and drive like a grandma but I believe you should drive a non turbo base model volvo. I feel bad for anyone who uses crappy oil and crappy gas
Ps. His all aluminum engine is only 9:1 so certainly he doesnt need 92 or better. Hmmmm his air intake is in the middle of the hood. Must be cold! As cold as an sti's intercooler
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Obviously it was a drastic conparison but what i was trying to prove is even in 2008 the factory can design an engine that requires 92. Now even in 10 years should he stop running premium to save a few dollars? I believe if you care enough about your car to change the oil yourself you may as well pay the extra 20 cents a gallon. if it states on the gas lid to run water would you pour gas in?
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I get what your saying cobra. If you want to save money like a goldstein run regular and drive like a grandma but I believe you should drive a non turbo base model volvo. I feel bad for anyone who uses crappy oil and crappy gas
All I'm saying is this:
The M42 WILL RUN FINE on 87 octane - others have also used 87 octane w/o issues as well - not only on this forum, but MANY other BMW forums...
Some of you are blowing it out of proportion. Just because the owner's manual states to use "91" does not mean that the vehicle cannot and will not operate properly on 87, 89, etc... Remember, the fuel technology has ADVANCED since these cars have been built. Sure, the manual can say use this fuel or that oil - but as you, I and others know and can read in any forum or online tech article - many vehicles (and vehicle owners) have used fuels, additives & oil other than those specified in such owner's manuals. I also stated in the original thread that IF your M42 is anything other than a STOCK naturally aspirated M42 that this thread may not be to your benefit or interest...
I'm also not trying to start any online "arguments", just a discussion - which has shown that others have successfully used 87 in their M42 w/o any adverse effects.
Here's two other interesting things to think about:
1) isn't 91 octane in Germany THE lowest octane fuel available at fuel station pumps? Hmmm....
2) 91 "RON" octane is equivalent to U.S. 87 CLC octane (here's an interesting article from 1997 - regardless of vehicle discussed, the RON & CLC info is the important factoids in this article and would apply to ANY vehicle...): http://type2.com/bartnik/octane.htm
:D
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Ps. His all aluminum engine is only 9:1 so certainly he doesnt need 92 or better. Hmmmm his air intake is in the middle of the hood. Must be cold! As cold as an sti's intercooler
LOL
You're comparing a naturally aspirated 130hp 20 year old engine to a new direct injection, turbocharged 300hp engine. Congratulations. You're clueless.
I'm totally with you here.... BUT.... our cars do not have knock sensors and cannot retard timing when pre-detonation is sensed. Sorry, if we drove the more modern M44 we'd be OK. E30 M42, no such luck.
155k miles and counting on 87 octane says you're wrong.
Obviously it was a drastic conparison but what i was trying to prove is even in 2008 the factory can design an engine that requires 92.
So what happens to evo owners in California where the highest octane you can get is 91? Should they not drive their cars?
$5 says if push comes to shove, the evo would run just fine on 87 as well. The ecu would retard timing and cut boost but the engine would be ok. In fact I'm willing to bet every last car sold in America will run on 87 octane for a very long time without engine damage.
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LOL
You're comparing a naturally aspirated 130hp 20 year old M42 to a new direct injection turbo engine. Congratulations. You are officially clueless.
I'm not comparing the 2 I'm comparing the idea of requiring premium fuel. They engineered it a certain way, I'm trying to say if they recommend it do it. If they require it you have to be a moron to run a dirty fuel. Learn sarcasim
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I'm not comparing the 2 I'm comparing the idea of requiring premium fuel. They engineered it a certain way, I'm trying to say if they recommend it do it. If they require it you have to be a moron to run a dirty fuel. Learn sarcasim
BWAHAHA! Ur hilarious. Dirty fuel?
You think the difference between 92 octane and 87 octane is dirt? We could all filter our fuel and magically turn 87 into 92. WOW, what a great idea!
LOL
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155k on 87 and I bet my 200k 92 octane has a bigger epeen I mean hp. To each his own but this thread is stupid. Let's recommend bad things openly! Don't change your oil until 20k!! Save 10 dollars in 4 months!
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BWAHAHA! Ur hilarious. Dirty fuel?
You think the difference between 92 octane and 87 octane is dirt? We could all filter our fuel and magically turn 87 into 92. WOW, what a great idea!
LOL
dirty meaning it sits in Arco's tank. Why do arco charge 15 cents less per gallon? Because there fuel sits for weeks and it becomes lower octane. I'm no chemist but this is easy to understand
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before this gets any more "heated" - and in case it has been missed:
91 "RON" octane is equivalent to U.S. 87 CLC octane (here's an interesting article from 1997 - regardless of vehicle discussed, the RON & CLC info is the important factoids in this article and would apply to ANY vehicle...): http://type2.com/bartnik/octane.htm
The above is also discussed on MANY forums and by googling the RON vs CLC measurements, there's tons of info where it seems that "91" overseas is the equivalent to "87" here in the U.S. (or visa versa)...
Do read the link.
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I'm sorry but the only person to bring up oil changes into this discussion is you. Thus far, you haven't been able to make a single compelling argument. You haven't provided any evidence to support your argument, you've made completely outlandish comparisons and you seem to think that using 87 octane is akin to 20k mile oil changes. And no offense but your grammar and spelling are not helping your argument.
I'll repeat my position in order to avoid any confusion. The previous owner of my car used 87 octane for 140k miles before I bought it without a hitch. When I bought the car I started by using 91 octane then reduced octane in order to see how it affects power and fuel economy. In stock form, this engine begins to knock on 89 octane at around 90f and 70f on on 87 octane.
The reason BMW recommends using only 91 octane is because the stock air intake is purposely designed to suck in hot air from the radiator between 122-158f.
Column 2, line 3
http://farm4.static.flickr.com/3159/2475132424_885e9f276f_o.jpg
With a cold air intake, you can bring the temperature inside the airbox to about 0-5f above ambient and safely use 87 octane at all times. So far I've driven my car on 87 up to 90f without a hint of knock or loss of power.
If you don't believe me you can easily use your outside temp sensor from inside the left side brake duct, and put it inside the airbox. This will allow you to monitor your intake temperature at all times through the OBC.
91 "RON" octane is equivalent to U.S. 87 CLC octane (here's an interesting article from 1997 - regardless of vehicle discussed, the RON & CLC info is the important factoids in this article and would apply to ANY vehicle...): http://type2.com/bartnik/octane.htm
Unfortunately in the US BMW defines "91 octane" as RON+MON/2. Thats 95 ron on the other side of the pond.
dirty meaning it sits in Arco's tank. Why do arco charge 15 cents less per gallon? Because there fuel sits for weeks and it becomes lower octane. I'm no chemist but this is easy to understand
Arco charges 15 cents less because they don't take credit cards, only debit. And on debit card transactions there is a 35 cent fee. Its in the fine print on every pump.
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dirty meaning it sits in Arco's tank. Why do arco charge 15 cents less per gallon? Because there fuel sits for weeks and it becomes lower octane. I'm no chemist but this is easy to understand
Not to get off topic, however:
I'm sure fuel across the world sits for more than "weeks" after it has been refined and processed into the storage tanks. This statement does not only apply to one Oil/Fuel company or certain parts of the world, it's just factual. There is no such thing as "freshly brewed" fuel, after all of the refining and processing, it's all pumped into storage facilities, of which tankers are filled and then it's transported to where ever...
Do you think the inside of a fuel tanker truck is 100% clean? Nope. How about those storage tanks (both above and below ground)? Nope. There's sediment, condensation, etc. that can and most likely does occur in those metal storage facilities & containers, be it stationary or mobile. Sediment settles to the bottom of any storage tank, so most likely, nearly every oil/fuel company out there has "dirty" fuel - to what degree of "dirty", who knows and is anyone's guess.
(also, oil changing has nothing to do with the thread topic... can we kindly skip off that subject)
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155k miles and counting on 87 octane says you're wrong.
I'm not disagreeing that you can run 87, especially with intake mods as you show, but the point of that post was to explain that the M42 does not have knock sensors, and therefore cannot retard timing to protect the engine.
It is a fact that probably 99% of modern fuel injected engines from OBDII on have knock sensors and will retard timing as much as possible to protect the engine. Totally agree. But the M42 does not have them so arguing on that basis alone isn't correct.
My point is that after spending the money I did to get my engine back together I'm cautious and looking at the info before I jump. I'll spend 2-3 more for now, but will probably switch to 87 as well. I've de-carboned my cylinders which helps as well.
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All this talk of "dirty fuel", octane loss after a few weeks time, higher octane "burning better" is so outside the realm of science it's sad.
Also, I have no doubt that 87 is ok under 90*F, especially if the engine is not under a lot of load or running high RPMs.
But here in SoCal it's 115* in the summer, add to that the heat soak and A/C running and an uphill grade would certainly pose issues at lower octanes. That's the main reason I'm saying that I'd be safest with the higher recommended octane of 91.
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I'm not disagreeing that you can run 87, especially with intake mods as you show, but the point of that post was to explain that the M42 does not have knock sensors, and therefore cannot retard timing to protect the engine.
I stand corrected.
But here in SoCal it's 115* in the summer, add to that the heat soak and A/C running and an uphill grade would certainly pose issues at lower octanes. That's the main reason I'm saying that I'd be safest with the higher recommended octane of 91.
Thats a good point. I would also use 91 octane in that situation even with the cold air intake.
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there really shouldnt be an arguement here. Our car requires 91 oct. My gramma is from typing posts on my iPhone. It loves to correct me. Just like u guys. Not changing oil increases wear. Running 87 oct does the same thing.
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For the record, the original E30 owners manual for US and Canadian models recommends for the 318i/s premium unleaded gasoline only (90 AKI or 95 RON).
Anyone with a DeLorean can verify this with BMW AG Munich, West Germany.
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For the record, the original E30 owners manual for US and Canadian models recommends for the 318i/s premium unleaded gasoline only (90 AKI or 95 RON).
Anyone with a DeLorean can verify this with BMW AG Munich, West Germany.
I respect my m42 because on my gas door it says premium fuel required. My dads SHO says premium recommended and that bitch pings like crazy with regular but he's an oldman so he only runs regular!
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Obviously it was a drastic conparison but what i was trying to prove is even in 2008 the factory can design an engine that requires 92. Now even in 10 years should he stop running premium to save a few dollars?
I have seen people claim this works. One problem, you are talking an engine that wanted premium when new, it needs premium even more now due to any carbon build up. Older cars still require the same treatment, or BETTER than new.
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Thanks sheep. The car says premium u gotta run premium if u want it to run as the engineers planned
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Running 87 oct does the same thing.
Ok. Prove it.
Thanks sheep. The car says premium u gotta run premium if u want it to run as the engineers planned
If i wanted my car "to run as the engineers planned", It would still have power steering, a 4.1 LSD, a 4 turn rack, The world's most idiot series of vacuum and coolant hoses hidden under the intake manifold, 2 throttle heaters, a 158f air intake, 4 foot long ignition wires, single pintle injectors, a clutch fan and my all time favorite, cosmoline. I think some of us have moved a little bit beyond what the engineers planned.
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havent done the math on our cars, but the later style with knock sensors not only de-tunes the engine, but you get about 2-3mpg less (im not blowing smoke either, this was on a 330ci, and a e38 740il both turned out better gas milage). Besides, whats 20 cents? Spread it over a year, if you fill up every week, thats only like $200. If you ask me, and im broke as all hell, $200 is not that bad of a payoff :rolleyes:.
Oh and i read in a previous post that Cheveron makes better explosions in the engine, if your fuel is "exploding" i dont think its running right, its supposed to "burn" ;).
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This pretty much sums up what the M42club is all about! :D
If i wanted my car "to run as the engineers planned", It would still have power steering, a 4.1 LSD, a 4 turn rack, The world's most idiot series of vacuum and coolant hoses hidden under the intake manifold, 2 throttle heaters, a 158f air intake, 4 foot long ignition wires, single pintle injectors, a clutch fan and my all time favorite, cosmoline. I think some of us have moved a little bit beyond what the engineers planned.
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Some of you guys should go work for BMW because it's obvious that you are way smarter that the top engineers that BMW hires to design there cars. It's amazing that these terribly designed cars still have such a following 17 years after they were first sold.
They state premium fuel because these are high compression engines with no knock sensors. While you may not always hear the detonations that does not mean it's not happening. You may not have engine failure in the next few thousand miles that does not mean your engine is not getting damaged. Even if you are not one to push the limit you probably still put the car under load enough to cause pinging, for instance going up a hill in a high gear.
If it's recommended to run premium that's what you should be running. If you want to save $200 a year sell your e30 and buy a Corolla, my wife's gets way better mileage than my e30 does and Toyota recommends regular fuel.
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I run 93 only, my mods are chip, intake, pulstar plugs, resistorless leads, and a little tuning by me. I tried to run 87 before my mods and my little "Natascha" knocked and pinged oh! it was ungodly. There is a Circle K around the block from me. They have 100 Octane. Natascha runs soooo! nice. And the smell. MMMMM! racing fuel smells soooo! nice. Higher Octane fuel permits less carbon build up. The fuel burns hotter which burns the carbon. Lower octane does not. Once in a while you should add an octane booster to help clean out the carbon build up.
Well, too bad Natascha can't talk, otherwise she would be telling you that the 100 octane gas is burning up her catalytic converters. Higher octane gas is more resistant to combusting under pressure, but also burns a little slower unless it is compressed more, this is why your engine might also feel like it is running smoother. That wonderful smell you get is from unburned fuel going into your exhaust, continuing to burn, and cooking your catalytic converter. So in the end, the fuel in the cylinders will burn colder and the fuel in the exhaust will burn hotter.
To each his own I guess. When you realize that the stock intake sucks in air at 158f it becomes pretty obvious why bmw requires 91 octane or better for this engine. There is nothing special about a 10:1 CR engine using 87 octane. My 10.7:1 CR volvo has been for the last 260k miles. Fix the intake problem and you can use 87 octane at all temperatures.
Also please don't tell me in not going to hear ping or knock. I've seen the difference octane can make for this engine depending on air temperature, altitude and load.
158F intake temperatures aren't that bad at all. Most cars have much higher intake temperatures than you would probably expect. One cause is that heat from the cylinders transfers into the engine head, and from there to the metal intake runners and metal intake plenum. So all the intake air has to pass through heated metal tubing. This is also why putting an air temp sensor in your airbox won't give a very accurate reading of what is actually going into your cylinders.
The reason I run chevron premium is because its not like that shell trash. Chev gas is better because it doesnt sit in the tank for a week. Its cleaner and thus provides better explosions. Riddle me this. My buddy has an evo x and chipped it to 320hp at the wheels. Now should he run regular? No? Should he not use synthetic? No! I get what your saying cobra. If you want to save money like a goldstein run regular and drive like a grandma but I believe you should drive a non turbo base model volvo. I feel bad for anyone who uses crappy oil and crappy gas
Ps. His all aluminum engine is only 9:1 so certainly he doesnt need 92 or better. Hmmmm his air intake is in the middle of the hood. Must be cold! As cold as an sti's intercooler
-Chevron and Shell are both good gas companies to buy from. Any gas company with a Top Tier approval sells good gas. Here is a list you should look at: http://www.toptiergas.com/retailers.html
-If gas sits in a tank for a week, in simple, it will not change "how well it explodes". Gas is relatively stable when properly stored, but I still will agree with you that a gas station with lots of business is probably the better pick than one without much business.
-The reference to your friend's car is pretty irrelevant. I don't see how that his car has 320hp makes any effect on what kinda gas he uses. Give me the resources and I could manage 320hp with regular gasoline on an evo, it would just be a lot harder. Also the fact that is engine is aluminum makes not difference on the gas he uses. His compression ratio is also irrelevant to the gas he uses, especially since the car uses forced induction.
dirty meaning it sits in Arco's tank. Why do arco charge 15 cents less per gallon? Because there fuel sits for weeks and it becomes lower octane. I'm no chemist but this is easy to understand
Obviously, you are not a chemist. If fuel sits for a very long time in a tank it will degrade if anything, and not just become lower octane gas. You treat lower octane rating gas like if it is lesser quality of fuel. It is just as clean and refined as premium. The only difference is how easily it ignites.
Some of you guys should go work for BMW because it's obvious that you are way smarter that the top engineers that BMW hires to design there cars. It's amazing that these terribly designed cars still have such a following 17 years after they were first sold.
They state premium fuel because these are high compression engines with no knock sensors. While you may not always hear the detonations that does not mean it's not happening. You may not have engine failure in the next few thousand miles that does not mean your engine is not getting damaged. Even if you are not one to push the limit you probably still put the car under load enough to cause pinging, for instance going up a hill in a high gear.
If it's recommended to run premium that's what you should be running. If you want to save $200 a year sell your e30 and buy a Corolla, my wife's gets way better mileage than my e30 does and Toyota recommends regular fuel.
I would love to work for BMW and that is definitely a possibility with my career path.
BMW engineers are obviously very smart and did a very good job engineering the E30 3-series. Often though, they are criticized for including overly complex engineering at the expensive of long term reliability/maintenance/cost. Also of course, it takes time to figure out some mistakes and technology does change.
Another reason that 91 octane fuel is recommended is that back when the E30 was produced, gasoline quality was not nearly what it is compared today. The E30 was produced towards the end of the era when gasoline was being transitioned from leaded to unleaded.
I would guess that now, with current technology, you could run 89 octane or "Plus" gasoline and it would perform the same as 91 octane or "premium" back in the 80's
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What!!! MKODAMA. do know what the CAT is for? I was designed for high temp. Its a ceramic block. It burns the unburned hydrocarbons to lower emissions. Higher octane fuel, wrapped headers and a hot cat will drastically lower hydrocarbon emissions. I wrapped my headers to take the heat out of the engine bay and put it down the exhaust to the cat to lower engine bay temp. Cooler engine bay temp means colder, more dense air for the engine. The Internal Combustion Engine was designed to burn oxygen. Fuel was just the catalyst to push the pistons. Fuel octane is very important. 87 89 93. 87 is for a lot of city driving and low compression engines. 89 is for mid-performance city, freeway driving. 93 is for high performance engines with high compression and good freeway driving. Look at Europe, In England (UK) they have one specific octane 95. The rest of Europe usually follows suit. So my point is this. High heat, high octane, AND A HOT CATALYTIC CONVERTER, does increase performance. The internal combustion engine is at its best at high RPM and High Temp. OK. You need to look at a cross section of a CAT. Maybe then you will understand things better.
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I wrapped my headers to take the heat out of the engine bay and put it down the exhaust to the cat to lower engine bay temp.
Enjoy your cracked header. You won't have to wait long.
I had no idea so many dedicated gear heads were completely clueless about octane and how it effects the spark ignition engine. I am in awe. High octane = high exhaust temperature? 87 octane is for city driving? Are you serious?
LOL
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Enjoy your cracked header. You won't have to wait long.
I had no idea so many dedicated gear heads were completely clueless about octane and how it effects the spark ignition engine. I am in awe. High octane = high exhaust temperature? 87 octane is for city driving? Are you serious?
LOL
werd
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Another reason that 91 octane fuel is recommended is that back when the E30 was produced, gasoline quality was not nearly what it is compared today. The E30 was produced towards the end of the era when gasoline was being transitioned from leaded to unleaded.
The octane rating tells you how much the fuel can be compressed before it spontaneously ignites. Higher compression engines like the M42 need 91 octane fuel, the M20 has low compression and runs great on 87 octane.
I would guess that now, with current technology, you could run 89 octane or "Plus" gasoline and it would perform the same as 91 octane or "premium" back in the 80's
I agree technology has changed since the early 90's so in today’s cars you can run a lower octane rating on a higher compression engine. Unfortunately our cars do not benefit from the latest technology available in the industry.
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Enjoy your cracked header. You won't have to wait long.
I had no idea so many dedicated gear heads were completely clueless about octane and how it effects the spark ignition engine. I am in awe. High octane = high exhaust temperature? 87 octane is for city driving? Are you serious?
LOL
Negative Nancy
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I am going to see some of the best bmw techs in my state and I'm going to ask there opinion on what grade fuel to run in a 10:1 inline 4. With full intake and exhaust. I'll get back to you with what the guys who went to school and deal with bmws everyday of the week say
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You had better tell them exactly what motor and model year you're talking about. "inline 4 with 10:1 compression" is a bit vague language to use when talking about something as precise as octane.
The M42 does not have knock sensors. I for one don't wish to spend my money rebuilding sh!t that shouldn't have gotten busted in the first place, so I'm going to continue running premium gasoline in my 91 M42 that doesn't have knock sensors. I don't need to consult a tech in order to follow instructions that are printed clearly in my car's owner's manual, and I don't need to ask a tech why I need to follow those instructions.
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good, make sure you tell them what temp it runs at and that it has no knock sensors or automatic timing adjustment.
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I might try this out in the fall/winter.
tjts1: Do you wot/redline it with the 87/89 octane? So as long as the intake temps stay below 158f, no pinging should occur?
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What!!! MKODAMA. do know what the CAT is for? I was designed for high temp. Its a ceramic block. It burns the unburned hydrocarbons to lower emissions. Higher octane fuel, wrapped headers and a hot cat will drastically lower hydrocarbon emissions. I wrapped my headers to take the heat out of the engine bay and put it down the exhaust to the cat to lower engine bay temp. Cooler engine bay temp means colder, more dense air for the engine. The Internal Combustion Engine was designed to burn oxygen. Fuel was just the catalyst to push the pistons. Fuel octane is very important. 87 89 93. 87 is for a lot of city driving and low compression engines. 89 is for mid-performance city, freeway driving. 93 is for high performance engines with high compression and good freeway driving. Look at Europe, In England (UK) they have one specific octane 95. The rest of Europe usually follows suit. So my point is this. High heat, high octane, AND A HOT CATALYTIC CONVERTER, does increase performance. The internal combustion engine is at its best at high RPM and High Temp. OK. You need to look at a cross section of a CAT. Maybe then you will understand things better.
Yes, the catalytic converter was designed for high temperatures, you are correct on that one. But don't think that it is impervious to heat. Excessively high temperatures will partially melt and destroy the ceramic element inside. Common causes for failed catalytic converters are overheating them or from clogging with excess fuel.
Gas octane is also measured different in the US compared to the EU. The US uses AKI or Anti-Knock Index, which is the average of the RON (Research Octane Number) and MON(Motor Octane Rating) ratings. Europe just uses the RON rating, and is why their fuel octane cannot be directly compared to ours.
For example:
The MON rating is usually 8 to 10 points lower than RON. If you say the european gas pump said 95 RON, it could also be said to be 85 MON. To get the AKI, like what is used in the US,
AKI = (RON + MON) / 2
AKI = (95 + 85) / 2
AKI = 90
So that would mean that 95 octane gas you saw is the equivalent to the "Premium" grade gas you see in the US.
And here's a fun fact: wrapping your headers and cat will create hotter exhaust temperatures and hotter exhaust temperatures or more prone to creating nitrogen oxides, a major pollutant that is measured during emission inspections.
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Enjoy your cracked header. You won't have to wait long.
I had no idea so many dedicated gear heads were completely clueless about octane and how it effects the spark ignition engine. I am in awe. High octane = high exhaust temperature? 87 octane is for city driving? Are you serious?
LOL
werd
+1
The octane rating tells you how much the fuel can be compressed before it spontaneously ignites. Higher compression engines like the M42 need 91 octane fuel, the M20 has low compression and runs great on 87 octane.
I agree technology has changed since the early 90's so in today’s cars you can run a lower octane rating on a higher compression engine. Unfortunately our cars do not benefit from the latest technology available in the industry.
Oh yeah, no doubt about that octane controls the auto-ignition of gasoline. I was just getting into some minor details. I fully agree with you on everything you stated.:D
Negative Nancy
(http://smiliesftw.com/x/rofl.gif) (http://smiliesftw.com)
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Another reason that 91 octane fuel is recommended is that back when the E30 was produced, gasoline quality was not nearly what it is compared today. The E30 was produced towards the end of the era when gasoline was being transitioned from leaded to unleaded.
I would guess that now, with current technology, you could run 89 octane or "Plus" gasoline and it would perform the same as 91 octane or "premium" back in the 80's
Yes, gas is better.
Is your cylinder, head, valves, and piston all shiny and new or does it have some carbon buildup? Are you sure? How is the intake path, injectors, plugs, timing system, etc... Are your cams still timed exactly stock?
Your engine is not new and will not run as good as new.
Can it perform as good, maybe, but the lower octane still requires a timing change to get an efficient burn. An inefficient burn can blow pistons and burn up your cat.
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havent done the math on our cars, but the later style with knock sensors not only de-tunes the engine, but you get about 2-3mpg less (im not blowing smoke either, this was on a 330ci, and a e38 740il both turned out better gas milage). Besides, whats 20 cents? Spread it over a year, if you fill up every week, thats only like $200. If you ask me, and im broke as all hell, $200 is not that bad of a payoff :rolleyes:.
Oh and i read in a previous post that Cheveron makes better explosions in the engine, if your fuel is "exploding" i dont think its running right, its supposed to "burn" ;).
That $200 will seem well spent if anything does go wrong.
You drive a BMW.
If you cannot afford to take care of it, you should get rid of it and buy something you can afford.
$200 would not cover almost any repair I have had to do so far. It definitely will not cover a timing chain or full rebuild. It won't even cover the parts required.
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If you guys want to save money, try looking up hypermiler. You could probably average 45mpg in our cars.
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tjts1: Do you wot/redline it with the 87/89 octane? So as long as the intake temps stay below 158f, no pinging should occur?
I wish I had my car to try it out today. It was the first day of the year over 100f. Unfortunately my GF has the car while I work on her volvo. So far I have only tested it at WOT up to 90f intake temp.
You drive a BMW.
If you cannot afford to take care of it, you should get rid of it and buy something you can afford.
I don't think this has anything to do with affording a BMW. I started out using low octane fuel out of curiosity. I wanted to see if there was a way to make this car run reliably on 87 octane without any compromises. So far so good. If ever kill it I'll buy another. But I doubt octane will have anything to do with this car's demise. My next experiment involves water injection. :D
Are you sure? How is the intake path, injectors, plugs, timing system, etc.
I don't know, you be the judge. My engine is full of bees.
http://farm4.static.flickr.com/3077/2496605756_c1fdd73074_o.jpg
http://farm4.static.flickr.com/3294/2495781545_5235c82284_o.jpg
http://farm3.static.flickr.com/2034/2496605722_4f04604dac_o.jpg
http://farm3.static.flickr.com/2025/2495781499_5a16af3de7_o.jpg
Ok i'll admit it. I cleaned it.
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Yes, gas is better.
Is your cylinder, head, valves, and piston all shiny and new or does it have some carbon buildup? Are you sure? How is the intake path, injectors, plugs, timing system, etc... Are your cams still timed exactly stock?
Your engine is not new and will not run as good as new.
Can it perform as good, maybe, but the lower octane still requires a timing change to get an efficient burn. An inefficient burn can blow pistons and burn up your cat.
Well, first of all, I don't even have my 318is in my hands yet:(, only a pinkslip.
But once I do, I will show you an engine so clean you'll be embarrassed to post pictures of your M42. :p
I definitely know what you mean though. I helped a friend do a head gasket change on his 1989 Mercedes 190E and I was amazed at all the junk in the intake, on the valves, and built up on the pistons.
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I don't think this has anything to do with affording a BMW. I started out using low octane fuel out of curiosity. I wanted to see if there was a way to make this car run reliably on 87 octane without any compromises. So far so good. If ever kill it I'll buy another. But I doubt octane will have anything to do with this car's demise. My next experiment involves water injection.
Water injection will eliminate detonation but the down side is less power, water does not burn. Back in the 80's I used to drive a 1971 Trans Am, even though it had 8:1 compression, with the timing advanced I would get some pinging. I used a water injection system but added methanol to the mix it was believed that the methanol would help with HP but to tell you the truth I never tried it at the track or on a dyno so I can't say if it worked or not.
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After reading over some online Bentley pages - here's a statement directly from the Bentley, page 120-6 (Ignition System):
Crankshaft Position Sensor (CMP)
The camshaft position (CMP) sensor is used by the engine management system for sequential fuel injection and knock control.
(http://i141.photobucket.com/albums/r73/bogeyman700/cps.jpg)
"Knock control" - based on the last 2 words of that published statement by the Bentley Authors, would'nt this mean that the CMP does in fact sense engine knock and therefore relays any such knock data back to the DME, which the DME would then take the appropriate actions to control air/fuel/spark?
? - open for discussion, as many are saying that the M42 does not have a "knock sensor" - maybe the CMP does sense engine knock as per the Bentley...
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The E30 M42 doesn't have knock sensors, but the E36 M42 does. I had knock sensors on the 1992 E36 engine I pulled.
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I understand that everyone says the E30 M42 does not have any actual "knock sensors" - but what I'm saying is, the Bentley is stating that the CMP serves (2) purposes - sequential fuel injection and knock control... Is the Bentley incorrect?
Just trying to figure out if the CMP does double duty or not, based on the Bentley.
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that Bently is for the E36 model right? Because the E30 model doesn't give the detailed M42 specs right?
I'm interested in what it says about the CMP sensor as well.
There are two different numbers for the sensor though.
E30 318is = 12141721861
E36 318is = 12141734813 could be a difference in function as well? They are the same size/location so no need for a new part number unless they are different.
Also, the E36 M42 block (and later M44) is the only M42 that includes item #15 "ping sensor". This is not present on the E30 variant.
(http://www.realoem.com/bmw/diagrams/c/c/6.png)
could be that the later M42 Ping Sensor works with the later CMP to send a delayed signal to the ignition.
I believe that the confusion is that you have to work with a manual that is made for the later engines. But, this gives me compelling reason to buy a 92+ M42 if my engine breaks.
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that Bently is for the E36 model right? Because the E30 model doesn't give the detailed M42 specs right?
I'm interested in what it says about the CMP sensor as well.
There are two different numbers for the sensor though.
E30 318is = 12141721861
E36 318is = 12141734813 could be a difference in function as well? They are the same size/location so no need for a new part number unless they are different.
Also, the E36 M42 block (and later M44) is the only M42 that includes item #15 "ping sensor". This is not present on the E30 variant.
could be that the later M42 Ping Sensor works with the later CMP to send a delayed signal to the ignition.
I believe that the confusion is that you have to work with a manual that is made for the later engines. But, this gives me compelling reason to buy a 92+ M42 if my engine breaks.
Hmmm... more good info!
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Here's even more good info. Nice read on the updates for the E36
http://www.motortraders.net/groups/group.asp?group=1&menu=87
To ensure that knock is reliably identified, BMW installed two knock sensors on its four-cylinder engines (many otherwise comparable systems for four-cylinder engines use only one sensor).
A multiplexer circuit in the engine control module analyzes the signals. This ensures that only the signal from the cylinder in which combusion is actually taking place is transmitted to the adjacent knock sensor. The multiplexer is switched correctly by evaluating the signal from the cylinder identification sensor (on the camshaft). The knock sensor is a piezoelectric conductor-sound microphone with a broadband characteristic. A piezo-ceramic ring is clamped by a spring washer between a seismic mass and the sensor body. If the seismic mass is accelerated, it exerts a force on the piezo-ceramic element. Opposed electrical charges build up on the upper and lower ceramic surfaces, and generate a voltage at the contacts. In this way, acoustic vibrations can be converted into electrical signals. These in turn are transmitted by shielded wires to the engine control module for processing.
(http://www.motortraders.net/groups/attachments/1_87_t9211u07.gif)
1 Shielded wire
2 Cup spring
3 Seismic mass
4 Housing
5 Inner sleeve
6 Piezo-ceramic element
The knock sensors are bolted to cast bases on the intake side of the engine block, between the 1st and 2nd and between the 3rd and 4th cylinders.
These locations ensure that even when knock is only slight that the acoustic vibrations emitted from the combustion chambers are transmitted reliably to the knock sensors.
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I was under the impression that the crank sensor on our engines was on the front of the block reading off the crank pulley.
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And if this isn't a page that should be stolen by m42club.com then I DON'T KNOW WHAT IS!: http://www.motortraders.net/groups/group.asp?group=1&menu=89
Spectacular info
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I was under the impression that the crank sensor on our engines was on the front of the block reading off the crank pulley.
It is.
(http://www.motortraders.net/groups/attachments/1_89_t9011u64.gif)
1. Fuel tank with pump
2. Liquid/vapor separator
3. Fuel filter
4. M1.7 control unit
5. Ignition coils
6. Spark plugs
7. Injectors
8. Fuel rail
9. Fuel pressure regulator
10. Coolant temperature sensor
11. Throttle valve potentiometer
12. Idle control valve
13. Active carbon canister
14. Evap. purge valve
15. Airflow meter
16. Air temperature sensor
17. TDC and RPM sensor
18. O2 sensor
19. Cylinder identification sensor
20. Battery
21. Ignition switch
22. Main relay
23. Fuel pump relay
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I was under the impression that the crank sensor on our engines was on the front of the block reading off the crank pulley.
Not to get off topic, but to supply useful info:
CPS & CMP are two totally different sensors (and most online parts catalogs & vendor sites sometimes do differentiate between the two, while 98% of the time do NOT! Realoem is the ONLY site that lists the correct part #'s for both, so when needing to order one or the other, be sure you go to realoem for the correct sensor part # FIRST before placing your order!)
CPS is located externally, is down by the crank and is inserted into a small bracket and it reads the crank teeth & spaces in between, relays that info back to the DME.
The CMP is located internally, up by the valve cover (near thermo housing) and is inserted w/ rubber o-ring into head. If ordering a new CMP, be sure it comes w/ a new o-ring, some do some don't.
The sensors do look similar - the CPS has a longer wire, while the CMP has a short wire. Both perform completely different functions.
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And if this isn't a page that should be stolen by m42club.com then I DON'T KNOW WHAT IS!: http://www.motortraders.net/groups/group.asp?group=1&menu=89
Spectacular info
WOW! I added that one to my "favorites"! Someone should definitely get that permanently stored & "sticky'd" to this site before it's no longer an available page in the future - EXCELLENT & VALUABLE M42 INFO.
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Ok so it is at the front of the crank
(http://www.motortraders.net/groups/attachments/1_89_t9011u68.gif)
Because the article in #91 (excellent info by the way) says "Locate sensor at left rear side of cylinder block" which would mean it runs off the flywheel. But I guess that only applies to E36 engines. I was confused. All is well now.
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Hmmm... based on that very informative link, it seems that the DME used in the PRE -1994 E36 M42 would be nearly identical as far as pinouts & functions as used in the prior E30 M42's - because the tech info provided states that both DME's were "1.7's".
The ONLY differences noted between the E30 M42 DME 1.7 and the PRE-1994 E36 M42 DME 1.7 are those in the shaded blocks below:
(http://www.motortraders.net/groups/attachments/1_87_t9211u08.gif)
The DME used AFTER 01/1994 uses DME 1.7.2. "A new version engine control module (DME 1.7.2) is used due to a final stage output modification for the ignition coil and all programming changes to accommodate the new air shroud injector system. DME pin designations remain the same when compared to DME 1.7."
http://www.motortraders.net/groups/group.asp?group=1&menu=88
(nomad - I started a new thread in the M42 Reference forum on here and pasted the link you found in there. There so much valuable & detailed tech info in the link you found that it's only appropriate to create a new thread for it).
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I wish I had my car to try it out today. It was the first day of the year over 100f. Unfortunately my GF has the car while I work on her volvo. So far I have only tested it at WOT up to 90f intake temp.
I don't think this has anything to do with affording a BMW. I started out using low octane fuel out of curiosity. I wanted to see if there was a way to make this car run reliably on 87 octane without any compromises. So far so good. If ever kill it I'll buy another. But I doubt octane will have anything to do with this car's demise. My next experiment involves water injection. :D
I don't know, you be the judge. My engine is full of bees.
http://farm4.static.flickr.com/3077/2496605756_c1fdd73074_o.jpg
http://farm4.static.flickr.com/3294/2495781545_5235c82284_o.jpg
http://farm3.static.flickr.com/2034/2496605722_4f04604dac_o.jpg
http://farm3.static.flickr.com/2025/2495781499_5a16af3de7_o.jpg
Ok i'll admit it. I cleaned it.
I think it has everything to do with owning a BMW.
If you cannot afford to feed it properly, you should not have it. Plain and simple. You are risking your motor for 20 cents a gallon.
As fro how clean your motor is, how are the pistons? Rings? Other side of the valves? Is there any casting flash?
BMW does leave some leeway in there, specifically for differences among engines, altitudes, wear and tear, etc... The problem is, you do not know if yours is one of the better or worse ones. How do you know if you did not get a piston with a slightly thinner casting in the top? Slightly deformed or more casting flash...
You can argue all you want about how good your engine is, the only true test is time. The only way to know is when it dies.
Again, all to save 20 cents a gallon.
Do you also run the cheapest oil you can get? How about filters? Tires?
Save that sort of thing for your Honda or Toyota where it will not matter. You drive a high end sports sedan that needs higher end parts.
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Get real. We drive $1000 beaters. This is no "high end sports car". It was the poverty spec bmw when it was new, its a 17 year old beater today that happens to be fun to drive and gets pretty good mileage. I'm sick and tired of all the "get a Honda if you can't afford a bmw" nonsense Have you looked at how much a 92-95 civic costs? If you want to stay on the safe side and use 91 octane all the time go ahead. Theses nothing wrong with that. But this whole theory that we are somehow not deserving of the all mighty BMW because we happen to run 87 octane is just plain BS. I'm willing to bet 90% of the 10+ year old bmws on the road are being fed 87 octane without a second thought. The first owner might have used 91 octane but once the car hits the used car market, all bets are off.
I filled up the tank at lunch today. 31.5 mpg on 87 octane.
cheers
Justin
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The problem is, you do not know if yours is one of the better or worse ones. How do you know if you did not get a piston with a slightly thinner casting in the top? Slightly deformed or more casting flash...
...You drive a high end sports sedan that needs higher end parts.
I'm not arguing anymore, just thought these two assertions did not really go together. ;)
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Get real. We drive $1000 beaters. This is no "high end sports car". It was the poverty spec bmw when it was new, its a 17 year old beater today that happens to be fun to drive and gets pretty good mileage. I'm sick and tired of all the "get a Honda if you can't afford a bmw" nonsense Have you looked at how much a 92-95 civic costs? If you want to stay on the safe side and use 91 octane all the time go ahead. Theses nothing wrong with that. But this whole theory that we are somehow not deserving of the all mighty BMW because we happen to run 87 octane is just plain BS. I'm willing to bet 90% of the 10+ year old bmws on the road are being fed 87 octane without a second thought. The first owner might have used 91 octane but once the car hits the used car market, all bets are off.
I filled up the tank at lunch today. 31.5 mpg on 87 octane.
cheers
Justin
Wrong, so wrong. Way to miss the point.
You drive a $1000 beater that was built as a high end sports sedan. It still requires parts like a high end car. You could almost buy 2 decent Mustangs for the price of a 318IS back when they were new.
When this car is 50 years old will it still be a beater? Current price has NOTHING to do with what a car requires for maintenance. It may be only a beater to you, but the engine and specs have not changed on it.
Do you really think the octane requirement goes down with age?
Maintenance has nothing to do with being a BMW. It has to do with what the car was designed for. If you drive a 1974 Mustang that requires premium, it still needs premium regardless of how old the car is or big of a pile of shit the car is. It's just an old Porsche, BMW, Mercedes, Ferrari, does not matter, they still require what they did when new. It being a BMW has to do with what you expect from it. It is not a Honda or Toyota you can just put whatever you feel like in it and expect it to keep running well.
Sorry, but people who think like you do piss me off. Just because something is old does not mean it is worthless or can be treated like crap and expect to keep performing as it once did. As a car ages it requires more, not less care. It is ass-backwards thinking.
As for what the Honda costs... B.S.
Have you tried finding an e30 in comparable shape? Also, take a look as total cost of ownership, not just initial buy in. HUGE difference there. If you find me a NICE e30 318IS for the cost of a 1992 Civic, let me know. I can find several Civics for around $3k (or less) in excellent shape, 318IS, good luck.
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Wrong, so wrong. Way to miss the point.
You drive a $1000 beater that was built as a high end sports sedan. It still requires parts like a high end car. You could almost buy 2 decent Mustangs for the price of a 318IS back when they were new.
When this car is 50 years old will it still be a beater? Current price has NOTHING to do with what a car requires for maintenance. It may be only a beater to you, but the engine and specs have not changed on it.
Do you really think the octane requirement goes down with age?
Maintenance has nothing to do with being a BMW. It has to do with what the car was designed for. If you drive a 1974 Mustang that requires premium, it still needs premium regardless of how old the car is or big of a pile of shit the car is. It's just an old Porsche, BMW, Mercedes, Ferrari, does not matter, they still require what they did when new. It being a BMW has to do with what you expect from it. It is not a Honda or Toyota you can just put whatever you feel like in it and expect it to keep running well.
Sorry, but people who think like you do piss me off. Just because something is old does not mean it is worthless or can be treated like crap and expect to keep performing as it once did. As a car ages it requires more, not less care. It is ass-backwards thinking.
As for what the Honda costs... B.S.
Have you tried finding an e30 in comparable shape? Also, take a look as total cost of ownership, not just initial buy in. HUGE difference there. If you find me a NICE e30 318IS for the cost of a 1992 Civic, let me know. I can find several Civics for around $3k (or less) in excellent shape, 318IS, good luck.
Wow! Too many good points! I hope this is the end of this lame thread! Thanks for representing the M42! These guys need to swap to M20 i believe they would be much better off!
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Sorry, but people who think like you do piss me off. Just because something is old does not mean it is worthless or can be treated like crap and expect to keep performing as it once did. As a car ages it requires more, not less care. It is ass-backwards thinking.
As for what the Honda costs... B.S.
Have you tried finding an e30 in comparable shape? Also, take a look as total cost of ownership, not just initial buy in. HUGE difference there. If you find me a NICE e30 318IS for the cost of a 1992 Civic, let me know. I can find several Civics for around $3k (or less) in excellent shape, 318IS, good luck.
You sure are aggressive for a site admin...
I think the issue is less of the car being old, but the current market value. If I just look on the local craigslist ads, it's easy to find one for not much. Just right now there is a 1991 white 318is with 160K miles and in good condition for $2800. I bought mine for around $1600, and I've seen "O.K." condition cars for less than $1000. In short, it's hard for people to spend much money on a car that isn't of much value to them and easy to replace.
Sorry, I just felt like I had to defend Justin since you are being a little too forceful in pushing your beliefs onto others.
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Oh come on all of you guys. it's the interweb, feelings are for kids.
Let's make sure we keep the discussion to the mechanical and engineering aspects of the topic. What is this going to be... Jerry Springer?
OK, there are lots of detailed scientific reasons why the engineers chose the octane rating new. There are also plenty of reasons why they need specific care used that they did not need new.
There are also ways of "re-engineering" certain aspects from an enthusiast's perspective as well.
Cars are designed with a certain give and take in order to please the general population. If we only wanted sports cars then they'd have low/stiff suspensions, stripped interiors and peaky powerbands. But the E30 was a combo of fun luxury and the M42 was an option for the "commoner".
Let's stick to the details, do a little research before we post and provide valuable, real knowledge.
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Oh come on all of you guys. it's the interweb, feelings are for kids.
Let's make sure we keep the discussion to the mechanical and engineering aspects of the topic. What is this going to be... Jerry Springer?
OK, there are lots of detailed scientific reasons why the engineers chose the octane rating new. There are also plenty of reasons why they need specific care used that they did not need new.
There are also ways of "re-engineering" certain aspects from an enthusiast's perspective as well.
Cars are designed with a certain give and take in order to please the general population. If we only wanted sports cars then they'd have low/stiff suspensions, stripped interiors and peaky powerbands. But the E30 was a combo of fun luxury and the M42 was an option for the "commoner".
Let's stick to the details, do a little research before we post and provide valuable, real knowledge.
JERRY! JERRY! JERRY!
haha, jk, very well said nomad.
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You sure are aggressive for a site admin...
Huh? The guy seems to know what he is talking about and likes the cars, what does his being the admin have to do with his views? Its not like he banned anyone for their opinion, we're all just having a discussion.
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the sky is falling, the sky is falling!
...
IMO, I fail to see the connection of ANY engine, regardless of type, HP, # of cylinders, compression, etc failing due to the SOLE sustained use of a lower or higher octane fuel.
Engine wear, tear and failure rate can be attributed to MANY variables - but to sit back and state that someone's engine will outright fail OR will possiby expire at X,XXX, XX,XXX or XXX,XXX miles just because they use Brand X fuel that has a lower or higher octane rating other than what is stated in the "Owner's Manual" is purely ridiculous.
I want to see an engine that has failed SOLEY due to the octane level of the fuel that was used. Such a failure should have facts to back up that the SOLE and ONLY factor due to such a failure was 100% attributed to the type of fuel used and that all other engine internals, externals, sensors, FPR psi, oil psi, coolant temp, oil viscosity, injector spray pattern and so forth were within factory operating spec, factory tolerances & it was maintained by proper maintenance as stated in the same owner's manual. Show me an M42 that has failed prematurely and was proven to have failed without any doubt due to only using a lower octane fuel other than what was recommended by BMW.
I don't see why anyone would think the topic of this thread is "stupid" - why, because others have successfully used 87 octane in a N/A stock engine with no adverse effects and don't feed into the "you HAVE to do this or else" hype? I think the thread has generated a ton of good, valuable and informative info from everyone who had input.
When this car is 50 years old will it still be a beater?
YES - to some and to some the car will still be just as "disposable" just like many others out there. As proven by some Members on here, some of the M42's can be had for as little as $300.00... and any used vehicle is only worth as much as someone is willing to pay for it. You can still pay $3k & higher for an M42 and end up w/ one that will still need mechanical work, could have an unexpected failure or one that was not maintained properly. The market varies based on geographic location, miles on vehicle, overall condition and if the buyer/seller are in agreement. Some are used as beaters, some are garage queens and some are restored former beaters... :D
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To each his own but I'm going to keep running the CORRECT octane gas because my car is a high compression 4 cylinder. If it was a pos American v8 I might run crappy gas
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Oh, I'm sorry, I thought this was a site meant for enthusiasts, not "I bought a BMW thinking it was cheap" or "how to keep your beater running as cheap as possible".
I never said it will fail at X number of miles.
Can we prove there was nothing else at fault, nope.
Is there scientific proof that you cannot hear all detonation, YES.
Is there scientific proof that detonation causes engine failures, YES.
And I never knew there was a rule that site admins could not be salty from time to time. I thought they were human just like the next person.
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Salty admins rule!
I don't daily drive my car, so it's a bit easier for me to run premium since I don't fill up much luckily. We're up to $4.25 for regular downtown!! Not sure where premium is at, I filled a full tank over mother's day in the sticks that should last me a bit.
Anyways, I have enough blood, sweat, and tears, let alone funds in my car to go by the owner's manual. To each their own though I guess. been reading this thread for a bit, it's been a fun one for m42club.com =) Finally felt like chiming in. It is a high-compression, high-revving 4 banger. I'd rather have it to spec, so I can rev it without any nagging worries in the back of my mind. To me, that's worth the extra $.20 a gallon.
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I thought they were human just like the next person.
And that's where you went wrong.
;)
OK, seriously. There is evidence that engines get irreparable damage from using too low of an octane. Predetonation needs to be controlled in all circumstances. Why the heck do you think there is even a computer controlling things? Fuel maps, timing advancements etc are all ways to control what is going on in the cylinder to make sure it is running correctly, that the spark ignites the fuel ,mix at the right time and that the flame front and expanding gasses impact the piston at the right moment in the stroke. If you don't think predetonation/preignition (also subsequent combustion temps) does not harm not only the efficiency of the engine but the wear and tear on piston heads, wrist pins rods, crank bearings and even cranks then you just don't know enough about internal combustion engines yet to respond effectively. Come on, do some research, go to a library (gasp!) or a bookstore and read up on the technology.
Why did BMW add knock sensors to the next iteration of the M42? Because the more control you have over ignition, fuel, timing and the more info you can read about what's going on in the cylinder the better you can run.
You need to know the answer to these questions before you can really analyze this topic effectively:
What is the relationship to cylinder compression and higher octane? How about in relation to forced induction engines? what does running lean or running rich mean? What are the dangers/issues of either? What is timing advance/retard and how does it relate to top dead center? What is the relation between fuel octane and ignition speed (flame front)?
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Oh, I'm sorry, I thought this was a site meant for enthusiasts, not "I bought a BMW thinking it was cheap" or "how to keep your beater running as cheap as possible".
Sheepdog, i love your posts, very educated compared to what most other people are saying.....but i have to disagree with you on your last post. i think the E30 is a cheap car for what you get, they dont cost much to maintain, they are fun to drive....and compared to most japanesse cars, they are very cheap, the only thing that makes most japanesse cars "cheap" to own is if you dont do regular maintnece on them they still run, BMW's on the other hand need there attention, thus, to the general public....they are "expensive" to own (because most people dont take care of their cars). Would you agree?
Another thing, i work in the automotive industry right now (gotta pay for college somehow) and i get this octane rating question alot! and not just for BMW's, i get porsche, mercedes, volvo, and Audi customers coming up to me and asking: do i have to run premium? here is my answer to keep it simple:
The more you can advance timing, the more power you get out of the engine, the higher the octane, the more it resists burning, so therfore you can advance the ignition timing more.
....i know, iknow there is more variables to it, but to the average joe it makes sense so im sticking to it. Did you know that BMW actually invented knock sensors? i little FYI:).
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here is my answer to keep it simple:
The more you can advance timing, the more power you get out of the engine, the higher the octane, the more it resists burning, so therfore you can advance the ignition timing more.
Thank you. Education is paying off already.
Also applies to forced induction. It is limited to a certain point when the strength of parts and mechanical limitations of the engines but yeah, most people just want one simple answer.
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the sky is falling, the sky is falling!
...
IMO, I fail to see the connection of ANY engine, regardless of type, HP, # of cylinders, compression, etc failing due to the SOLE sustained use of a lower or higher octane fuel.
Really? I couldnt see a fuel that was too high of an octane causing engine problems, but there is plenty of evidence to prove that too low of an octane can hurt your engine(since we're talking about ANY engine here).
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Sheepdog, i love your posts, very educated compared to what most other people are saying.....but i have to disagree with you on your last post. i think the E30 is a cheap car for what you get, they dont cost much to maintain, they are fun to drive....and compared to most japanesse cars, they are very cheap, the only thing that makes most japanesse cars "cheap" to own is if you dont do regular maintnece on them they still run, BMW's on the other hand need there attention, thus, to the general public....they are "expensive" to own (because most people dont take care of their cars). Would you agree?/QUOTE]
Thanks that was sort of my point. Buy-in is pretty similar, to a point, for the same money you will typically get a nicer Japanese car. An "okay" e30 is cheap or similar in price to a decent Japanese car, a nice one is up there and on the rise. Upkeep however is way higher on these compared to Japanese cars. These cars were designed to wear out, Japanese cars are designed to live forever.
I never though of a BMW as a cheap beater, they are far too delicate for that.
Cheap BMW's are like cheap Ferrari's... "Wow a cheap 308! It only needs the fender fixed." Then you realize that fender repair costs more than the car in good condition (sadly enough, this is true about them).
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Some very good info and opinions being posted here!
And I never knew there was a rule that site admins could not be salty from time to time. I thought they were human just like the next person.
Usually other site admins get moderators to do their dirty work for them.:p
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Those of you who think it's a cheap car and you can run it on whatever crap you find and don't believe it's worth maintaining properly, I thank you. Because of you my well kept 1991 318is will be worth more money sooner.:D
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Those of you who think it's a cheap car and you can run it on whatever crap you find and don't believe it's worth maintaining properly, I thank you. Because of you my well kept 1991 318is will be worth more money sooner.:D
(http://smiliesftw.com/x/rofl.gif) You are a smart person!
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If you read your manual you will find your way of driving your 318 is not good for it. The manual tells you you need to get it up above 3k regularly. In fact they give a ratio of how much above and below you should spend.
These cars were meant to be flogged, not granny shifted.
As I said, am sure you can get away with it, but it is not worth it to me. Too much risk.
I have no idea about the 12 miles, but if that were true, I would have just been on fumes. Most cars with a light like that come on around 1-3 gallons left.
it has 1.6 gallons left...thats what the manual says
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As a random update, I have been gradually running octane from 91 to 87.
I normally just half of 93 and 87 at the pump, since Jersey has options of 87, 89, and 93. Only exception I have seen to this is Sunoco that has 91 also.
This pass fillup, I said fudge it, and filled it with 87. I WOTed it several times and cruised around for a while. Drove up to NYC, and had zero problems. The other day, it got pretty hot outside. The idle started to freak out, but I had that issue on hot days with 91. Later that evening, the idle returned to normal.
If I ever plan to run the car hard like at autox or the track, I would put 91 or 93 in it. Otherwise, I don't see any problems with 87.
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I ran 89 in my 95 318i (M42) for quite awhile without any problems. I switched to 93 and it just feels better. Hard to explain. The motor just feels happier to have the higher octane rating. BMW engineers their cars to run a specific way.
Also, I like to rev the M42 any chance I get, and I would not want to do that here in Florida with 87.
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I ran 89 in my 95 318i (M42) for quite awhile without any problems. I switched to 93 and it just feels better. Hard to explain. The motor just feels happier to have the higher octane rating. BMW engineers their cars to run a specific way.
Also, I like to rev the M42 any chance I get, and I would not want to do that here in Florida with 87.
The E36 has knock sensors, so when it detects pinging with the lower octane, it pulls the spark timing back, which usually results in less engine power. When you put the proper octane back in the tank, the car was able to run with optimal timing.
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Oh no 87 octane killed my engine!!!!
Just kidding. 153k miles and counting on 87 octane. I'll be sure to post here when i kill my engine using the wrong fuel.
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I only ran 98 octane fuel (chipped m42).We dont have 87 91 and 93 octane fuels here.:p
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I only ran 98 octane fuel (chipped m42).We dont have 87 91 and 93 octane fuels here.:p
Your octane is probably measured in RON units, while ours is measured in AKI (RON+MON/2).
98 is probably the equivalent to 93 AKI.
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dont forget if you live over say 4,000 feet above mean sea level (MSL) 87 octane will be the same as 91 octane because of less oxegen. When i lived in Taho (6,300 MSL) i ran 87 no problem.
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dont forget if you live over say 4,000 feet above mean sea level (MSL) 87 octane will be the same as 91 octane because of less oxegen. When i lived in Taho (6,300 MSL) i ran 87 no problem.
Is there a sensor that tells the car if its above sea level? A friend with an E30M20 told me if he unplugged that sensor on the dyno he gained +2 hp
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Is there a sensor that tells the car if its above sea level? A friend with an E30M20 told me if he unplugged that sensor on the dyno he gained +2 hp
As opposed to being below sea level? :confused: Most cars are made to be above sea level. Either way, in the case of the M42, it doesn't really matter. The amount of fuel that goes in is just calculated by the intake air temp sensor and the flappy air flow meter.
I'm pretty sure there is no sensor you can unplug and gain hp.
The closest thing I have heard of was in the US variant of the Mercedes 190E, there was a resistor that retarded the ignition timing slightly to compensate for the not so good gas we had in the US back in the 80's. Then again, I have never seen any hard evidence.
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As opposed to being below sea level? :confused: Most cars are made to be above sea level. Either way, in the case of the M42, it doesn't really matter. The amount of fuel that goes in is just calculated by the intake air temp sensor and the flappy air flow meter.
I'm pretty sure there is no sensor you can unplug and gain hp.
The closest thing I have heard of was in the US variant of the Mercedes 190E, there was a resistor that retarded the ignition timing slightly to compensate for the not so good gas we had in the US back in the 80's. Then again, I have never seen any hard evidence.
Blah blah blah blah how can an air temp sensor determine your altitude? If an M20 has a sensor for altitude why wouldn't our engine?
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+2 HP falls within the statistical error range for the dyno runs...
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Blah blah blah blah how can an air temp sensor determine your altitude? If an M20 has a sensor for altitude why wouldn't our engine?
No, haha, of course a temp sensor can't determine altitude. It's that flappy air flow meter that compensates for altitude. The less dense air at high elevations will move the flappy meter thing less, and slightly less fuel will be injected since there is less air. Make sense?
For all I know, the M42 and later fuel injected M20's had a second barometric sensor for continuous altitude correction. I don't know but I have yet to see one listed in the ETK.
But yeah, the M42 is pretty good right from the factory in my opinion, no reason to start unplugging sensors.
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No, haha, of course a temp sensor can't determine altitude. It's that flappy air flow meter that compensates for altitude. The less dense air at high elevations will move the flappy meter thing less, and slightly less fuel will be injected since there is less air. Make sense?
For all I know, the M42 and later fuel injected M20's had a second barometric sensor for continuous altitude correction. I don't know but I have yet to see one listed in the ETK.
But yeah, the M42 is pretty good right from the factory in my opinion, no reason to start unplugging sensors.
Thanks?
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Between the TPS, Barn door airflow meter, Air intake temp you can get a pretty decent altitude reading. But then of course it will not compensate for different pressures due to weather and climate. Im pretty sure it is probabally set in the DME for a standard pressure of 29.92 at sea level. Our cars are not that great of performers at higher elevations. But then again no car is. Im used to flying airplanes where the the pilot can set fuel mixture on the fly (but then again cars where not made to have drastic changes in altitude, in short time;)).
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Between the TPS, Barn door airflow meter, Air intake temp you can get a pretty decent altitude reading. But then of course it will not compensate for different pressures due to weather and climate. Im pretty sure it is probabally set in the DME for a standard pressure of 29.92 at sea level. Our cars are not that great of performers at higher elevations. But then again no car is. Im used to flying airplanes where the the pilot can set fuel mixture on the fly (but then again cars where not made to have drastic changes in altitude, in short time;)).
Many new cars compensate for altitude. Like, even the EFI controller I just built has an option for contnuous barometric correction. I'm seriously itching to put that controller on an m42!
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The previous owner of the car ran it with the crappiest octane he could find and was too cheap to put premium in it. It gummed everything up in the engine and i had to replace and clean a lot of internal parts because of it. Once in a while is OK but don't do it forever.
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The previous owner of the car ran it with the crappiest octane he could find and was too cheap to put premium in it. It gummed everything up in the engine and i had to replace and clean a lot of internal parts because of it. Once in a while is OK but don't do it forever.
How did you establish cause and effect? What parts exactly were "gummed up"? How often did the previous owner change the oil? What kind of oil did he use?