Author Topic: Tips for Improving Mileage, Most of Which Simple (Read 36304 times)

D. Clay · « **Reply #105 on:** June 22, 2007, 11:26:59 PM »

The gears need to work with the torque and horsepower curves. You can compensate by keeping the revs up or downshifting more going uphill, etc. A taller gear can lose it's on paper advantage. Anyone who has worked with gear software knows that you can put a gear in there that will go x MPH @7000 RPM but the motor won't pull it. The biggest fuel saver is keeping your foot out of it.
On aero, a big part of the drag is the E30's dated window openings, mirrors, drip rails, flat front, and general "brick" shape. .35 sounds about right.

tjts1 · « **Reply #106 on:** June 30, 2007, 05:00:59 PM »

I just finished installing the 3.64 in the car this morning. Took it for a 30mile shopping trip and I'm very satisfied. I can actually use first gear for more than a split second. It doesn't feel like I'm running out of revs. Also in real world driving its quicker to 60 since I only have to shift once. On the highway, 4th gear is identical to my old 5th gear, and fifth finally feels like a real over drive. Theres less acceleration in 5th than before but thats the whole point of overdrive. You trade off acceleration for fuel economy and comfort. I can always down shift to 4th or 3rd if I want to take off like a mad man. 60 mph @ 2500rpm, 80mph @ 3300 from the 3700rpm I was running with the 4.1.
The theory about the engine torque curve not working with 3.64 is bunk. Try it before you knock it. I like it and I'll probably end up selling my 4.1 LSD. I have a 1000 mile round trip to SoCal next week. I'll report back on fuel consumption.

sheepdog · « **Reply #107 on:** July 01, 2007, 11:51:19 AM »

Quote from: tjts1;28849

I just finished installing the 3.64 in the car this morning. Took it for a 30mile shopping trip and I'm very satisfied. I can actually use first gear for more than a split second. It doesn't feel like I'm running out of revs. Also in real world driving its quicker to 60 since I only have to shift once. On the highway, 4th gear is identical to my old 5th gear, and fifth finally feels like a real over drive. Theres less acceleration in 5th than before but thats the whole point of overdrive. You trade off acceleration for fuel economy and comfort. I can always down shift to 4th or 3rd if I want to take off like a mad man. 60 mph @ 2500rpm, 80mph @ 3300 from the 3700rpm I was running with the 4.1.
The theory about the engine torque curve not working with 3.64 is bunk. Try it before you knock it. I like it and I'll probably end up selling my 4.1 LSD. I have a 1000 mile round trip to SoCal next week. I'll report back on fuel consumption.

Pretty close to what I had expected.
I would be interested in the 0-60 times, I guess I can run the sim and check that.

I am curious about the mileage mostly, just to see how accurate that program was.

christophbmw · « **Reply #108 on:** July 03, 2007, 07:19:59 PM »

Quote from: tjts1;28849

I just finished installing the 3.64 in the car this morning. Took it for a 30mile shopping trip and I'm very satisfied. I can actually use first gear for more than a split second. It doesn't feel like I'm running out of revs. Also in real world driving its quicker to 60 since I only have to shift once. On the highway, 4th gear is identical to my old 5th gear, and fifth finally feels like a real over drive. Theres less acceleration in 5th than before but thats the whole point of overdrive. You trade off acceleration for fuel economy and comfort. I can always down shift to 4th or 3rd if I want to take off like a mad man. 60 mph @ 2500rpm, 80mph @ 3300 from the 3700rpm I was running with the 4.1.
The theory about the engine torque curve not working with 3.64 is bunk. Try it before you knock it. I like it and I'll probably end up selling my 4.1 LSD. I have a 1000 mile round trip to SoCal next week. I'll report back on fuel consumption.

thank you for the update! thats excactly what i wanted to hear, im thinking of the 3.91 though.

91318isguy · « **Reply #109 on:** July 05, 2007, 01:08:12 PM »

Question on the synthetic lubes. I was told that after 75K on the engine that it doesn't do any good and can sometimes damage the parts . This is coming from my mechanic who as busy as he is I gave $600 for my car.

christophbmw · « **Reply #110 on:** July 05, 2007, 07:11:59 PM »

Quote from: 91318isguy;29130

Question on the synthetic lubes. I was told that after 75K on the engine that it doesn't do any good and can sometimes damage the parts . This is coming from my mechanic who as busy as he is I gave $600 for my car.

maybe on a newer car, on our cars i would not not even consider using synthetic oils.

tjts1 · « **Reply #111 on:** July 09, 2007, 05:48:49 PM »

1 week and 1200 miles later...
32mpg average for the trip. Loaded up the car with 3 people and all our stuff, the AC was on 90% of the time, keep the speed between 75-90mph. 80% highway driving, 20% city and LA bumper to bumper. Thankfully no tickets but those speed traps sneak up on you. Temp ranged from 60f to 110f.
The 3.64 performed flawlessly even climbing the Grapevine in 4th at 80mph. More import than fuel economy, the taller diff makes the cabin a quieter place to sit for hours on end.
More later. Time for a nap.

sheepdog · « **Reply #112 on:** July 09, 2007, 06:49:58 PM »

Quote from: tjts1;29302

1 week and 1200 miles later...
32mpg average for the trip. Loaded up the car with 3 people and all our stuff, the AC was on 90% of the time, keep the speed between 75-90mph. 80% highway driving, 20% city and LA bumper to bumper. Thankfully no tickets but those speed traps sneak up on you. Temp ranged from 60f to 110f.
The 3.64 performed flawlessly even climbing the Grapevine in 4th at 80mph. More import than fuel economy, the taller diff makes the cabin a quieter place to sit for hours on end.
More later. Time for a nap.

Wow.
Better than I expected overall.

ecpreston · « **Reply #113 on:** July 09, 2007, 06:50:39 PM »

Quote from: christophbmw;29142

maybe on a newer car, on our cars i would not not even consider using synthetic oils.

WHY oh why do some people hang onto this fear of synthetic oils? They are good for ALL cars. I've done synth in the engine and trans of the few e30's and e36 I've owned, as well as engine oil on two Fieros, a '90 Accord, 240SX, pretty much every car I've owned that I actually wanted to keep for a little while. All cars at least 10 years old with 100k+ miles on them.

The people at the few race shops where I've worked, parts places, my car enthusiast friends, diesel truck friends, they all do synthetics. It's an easy choice, both in cost of oil changes, fuel economy, and engine life. I've never firsthand met an enthusiast who feared them, but they're obviously still out there..... somewhere! :confused:

FWIW, on my last trip to and from Summit Point Raceway in my m42, with stock diff, SYNTHETICS in trans, diff, engine, and even with sticky Azenis tires, and the sunroof cracked or open, windows partially down, 100lbs of tools in the trunk, I averaged 35MPG. Stock, 150k mile engine, with the only "mod" being the lack of a cat.

sheepdog · « **Reply #114 on:** July 09, 2007, 06:55:04 PM »

Quote from: ecpreston;29311

WHY oh why do some people hang onto this fear of synthetic oils? They are good for ALL cars. I've done synth in the engine and trans of the few e30's and e36 I've owned, as well as engine oil on two Fieros, a '90 Accord, 240SX, pretty much every car I've owned that I actually wanted to keep for a little while. All cars at least 10 years old with 100k+ miles on them.

The people at the few race shops where I've worked, parts places, my car enthusiast friends, diesel truck friends, they all do synthetics. It's an easy choice, both in cost of oil changes, fuel economy, and engine life. I've never firsthand met an enthusiast who feared them, but they're obviously still out there..... somewhere! :confused:

I agree, I think the fear is overblown.

One thing I attribute to this though is that many when they switch to synth, they also drop the weight of the oil, so of course you will be more likely to have a leak.

However, I also think synth is overblown in regards to how good it really is.

ecpreston · « **Reply #115 on:** July 09, 2007, 07:04:44 PM »

Quote from: sheepdog;29314

However, I also think synth is overblown in regards to how good it really is.

heh, tell that to our Accord that only gets it changed every 12-14k miles, a filter change every 6-7k. We've put 100k on it, now with 185k, it still runs like a top. Last time I did a compression test and oil sample, it was pretty uninteresting. Seems to be doing great.

Sorry, didn't mean to sidetrack the fuel economy conversation. :p

tjts1 · « **Reply #116 on:** July 09, 2007, 07:31:01 PM »

Quote from: ecpreston;29311

FWIW, on my last trip to and from Summit Point Raceway in my m42, with stock diff, SYNTHETICS in trans, diff, engine, and even with sticky Azenis tires, and the sunroof cracked or open, windows partially down, 100lbs of tools in the trunk, I averaged 35MPG. Stock, 150k mile engine, with the only "mod" being the lack of a cat.

Keep in mind that the sticky 195/60R14 Falken Azenis tires are 3.22% smaller than the stock 195/65R14 size on which the odometer is calibrated. 35mpg is closer to 33.5mpg. Thats still excellent fuel economy by any standard especially considering that the EPA rated our cars at 20mpg city, 25mpg highway for some strange reason. Most other cars under perform the EPA numbers. The lack of a catalytic converter will improve fuel economy by about 5% on most cars.

I think sheepdog's estimate of about 7% was dead on. Thats what a 3.64 is worth in MPG. Not a world of difference in fuel economy but very significant reduction in noise. I wish I had a Db meter to back that up with numbers.

One thing I didn't have on the car for this trip was a lower front air dam. I think an IS type air dam would reduce drag. Maybe next time.

sheepdog · « **Reply #117 on:** July 09, 2007, 07:43:28 PM »

Quote from: ecpreston;29316

heh, tell that to our Accord that only gets it changed every 12-14k miles, a filter change every 6-7k. We've put 100k on it, now with 185k, it still runs like a top. Last time I did a compression test and oil sample, it was pretty uninteresting. Seems to be doing great.

Sorry, didn't mean to sidetrack the fuel economy conversation. :p

Yes, but test ave also shown that changing any oil every 3000 is also bad for your engine.

Not to mention the fact that they have been saying every 3000 miles for how many years? Despite the fact that engines have better filtration and oils. Sorry to disapoint you, but I have seen Honda's and Toyota's go that far between changes with regular oil. Not a good idea, but I have seen it done with no real side effects. Go look at some old Nissan's, they can have more miles than that with very poor care.

The 3000 miles thing is a myth created by oil companies.

Alpine003 · « **Reply #118 on:** July 10, 2007, 12:12:35 AM »

Quote from: tjts1;29317

Keep in mind that the sticky 195/60R14 Falken Azenis tires are 3.22% smaller than the stock 195/65R14 size on which the odometer is calibrated. 35mpg is closer to 33.5mpg.

Well if you wanna nit pick, one can also argue that having 4 people in the car will lower the car enough to change the cd of the car and thus enhancing long distance hwy mileage. haha. j/k. :p

Good job on taking a stab with the lower diff ratio. It would interesting to see someone with a stock rear diff do some side by side pulls next to you to .

tjts1 · « **Reply #119 on:** July 10, 2007, 12:16:55 AM »

Quote from: Alpine003;29338

Good job on taking a stab with the lower diff ratio. It would interesting to see someone with a stock rear diff do some side by side pulls next to you to .

I think thats a foregone conclusion. I'm trying to get a hold of an accelerometer before I swap the 4.1 LSD back in for an AutoX I have coming up. Hopefully I'll get some back to back acceleration numbers on the same car.