M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: 2002maniac on March 20, 2006, 10:56:49 AM
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Ok. Since my motor burns oil, and has relatively low compression, I have been wanting to build up a motor for some time.
I originally wanted to do the M47n crankshaft but I realized that custom pistons would definately be needed and that doesnt quite fit in my budget. I bought 5 S52 pistons from a guy on bimmerforums who broke a valve and damaged one piston. Since it was an incomplete set (for the 6-cyl guys) I got them for almost nothing!
I am going to go pick up a high mileage motor as soon as the guy get it out of his totalled car.
The S52 has a 89.6mm stroke and uses a 135mm rod. The M42 of course has a 81mm stroke and uses a 140mm rod. If the deck height is the same in both motors we can calculate the pin height (EDIT it isnt so we cant!). It turns out to be 179.8 for the S52 and 180.5mm for our beloved M42. From this we can see that the S52 piston sits .7mm higher in the bore than the M42. (EDIT this was all great in theory, but it doesnt work) I doubt there will be any valve contact in this configuration, but as you will see, the CR will be a bit too high for street use anyway.
I'll be using the M44 headgasket which comes in 2 different thicknesses from the dealer.
I'll have to wait until I get my pistons and head so I can know for sure how much to mill off the pistons but I think it will be between 1.5-2mm off the squish ring. I am shooting for 11:1 CR since a lot of S14 guys run that on California gas at sea level with no problems.
If you have any questions, shoot...
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Just one question. Is this going to be a race only engine, or will it see significant ammounts of street time? Just wondering
Brian
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Sounds like a neat project. As always, I have to know what engine management you will be using. The Motronic could work fine if you put in injectors that are of a higher flow rate proportional to the increase in displacement. The only real worry is in the open-loop operation at WOT, and with the properly sized injectors it should not really be an issue. The ignition timing would seem to need some modifications since the CR is going up, but I have heard of folks making changes like this w/o software modification. Keep us posted!
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Just one question. Is this going to be a race only engine, or will it see significant ammounts of street time? Just wondering
Brian
This is my daily driver. I expect it to run with no detonation on 91 octane. The S14 guys are fine at sea level so I think I should be ok at 5000ft elevation.
Air will be metered by a 2.75" MAF and controlled by an SMT6 piggyback.
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f that. Just do it right with the m47 crank. Save up as long as you need, in not like you need the motor right now. And didnt the guy on bimmerforums just shave the top of his pistons?
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didnt the guy on bimmerforums just shave the top of his pistons?
Almost 4mm. That is alittle too much for my comfort. That method makes for a small space between the piston face and the ring lands.
Custom forged pistons are ~$450-600
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f that. Just do it right with the m47 crank. Save up as long as you need, in not like you need the motor right now. And didnt the guy on bimmerforums just shave the top of his pistons?
AS some of us have stated on r3v, don't think what he did is a simple plug and play. There is a descrepancy with the diesel cranks, they rare as heck and there's more machine work involved with his process than you can see.
Not trying to rain on your parade for the m47 set up as it will most likely just end up being another project that never makes it to fruition. Nothing wrong with being the innovator but it comes at a huge cost. If you do get the SAME exact crank and can confirm with the overseas shipper, rock on. We all know that's never the case with most overseas or even local parts dealings.
Back on topic; rock on with this 1.9l high compression mission :)
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Sounds awesome, let us know how it ends up and goes along the way.
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Yeah, I second the first idea for doing this. Getting an M47 crank is tough, and there is some hard machining that needs doing. Let's see if we can come up with some sort of home-brew solution, that is nice & reputable as well!
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Yeah, I second the first idea for doing this. Getting an M47 crank is tough, and there is some hard machining that needs doing. Let's see if we can come up with some sort of home-brew solution, that is nice & reputable as well!
how much would a custom crank cost? i'm sure you can get one CNC'd or somthing... that might defeat the whole cost idea, but atleast you wouldn't have to find one then?
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Machining one would not be cost effective by any means. And, you want a forged one anyway. Not saying the M4 crank is a bad idea, but it isn't the easiest.
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you can get a forged block, and machine it out of that. i guess oil journals would be hard to machine...
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Hehe, quite the optimist. Hell, if you can find a way to pull it off, hats off to you! The thing is that it must be forged into its shape. Machining cuts grain boundaries and does other stuff like heat/anneal the metal, and can lead to crack propagation in the metal. The M47 crank is sounding better by the minute lol.
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nice project! be interesting to see what you get from this. what HG are you going to run? and just out of interest, why this route rather than m44?
oh and i've said it before but if anyone wants an m47 crank i'd imagine i could find one over here without too many problems, the issue is cost, as these are expensive, heavy to post and then require mods to fit.
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I'm def. watching this one with interest also. Even though I don't have any plans for the immediate future, it's always nice to have options for when rebuild time comes around.
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I'll be using a M44 headgasket which has an 86mm bore.
The reason I didnt go with a M44 to start with is that the M44 has a cast crank that is not even fully counter-weighted.
I think the added compression ratio will also give much better response and power.
I am still waiting for my core to be pulled from the car :(
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I'll be using a M44 headgasket which has an 86mm bore.
The reason I didnt go with a M44 to start with is that the M44 has a cast crank that is not even fully counter-weighted.
I think the added compression ratio will also give much better response and power.
I am still waiting for my core to be pulled from the car :(
sure, but in practice it makes very little difference imo (that's from experience, i've been in an m44 engined e30, and my brother owns an m44 e36). the m44 crank has been proven to be able to cope with high rpm and high bhp etc, it is also pretty light so you get nice low rotating mass. when you say not fully counterweighted, it IS counterweighted, it just uses half the number of counterweights of the e30 crank! you could always lightly skim the head to bring up the CR a little, even go with oversize pistons etc.
you'd get a much newer block which wouldn't have 15+ year old water channels etc. and it would probably cost less. you'd also get the revised oil squirters, newer front timing gear, pulleys etc.
my 2.1 is running 11:1 CR, was intrigued to see whether you were going to run the m44 gasket, i've been considering it, but think i may go custom to get the correct bore, i have no idea whether the m44 one will work well being a smaller dia.
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Update + slight change of plans.
I had the block bored for the S52 pistons $200
The guy I bought the pistons from had planned on using them in a turbo motor and had had the oil ring groove modified for Total seal rings so I called up total seal and got a set of rings
I FINALLY found time to finish the pistons. I ended up milling 2mm off the deck and then I had to redo the valve pockets. This turned out to be a huge PITA due to the funky setup I had to do. I am happy with the outcome though and I dont think there is any way that the integrity of the pistons was compromised.
I also have decided to use an M44 crank even though it is cast and not fully counterweighted. I have seen M44 make plenty of power with superchargers or turbos and they seem to hold up just fine.
This isnt a race motor by any means and I'll be keeping the RPMs to 7200max so i'm not really worried about the crank.
I am still going to double and triple check all my measurements but heres what I have:
Combustion chamber volume 34CC
Piston dish 10cc
deck height .5mm
Displacement will be just short of 2 liters.
According to a few internet calculators, I should have ~9.5:1 CR. A little lower than I hoped, but that makes my decision to boost it much easier :D
here's the money I've spent on parts so far:
pistons-100
Bore block, hot tank, and gap rings-200
rings-120
Crank-175
Pics!
(http://img.photobucket.com/albums/v485/2002maniac/IMG_0471.jpg)
(http://img.photobucket.com/albums/v485/2002maniac/IMG_0472.jpg)
Valve pocket detail.
(http://img.photobucket.com/albums/v485/2002maniac/IMG_0473.jpg)
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lookin good!! I can't wait to see how it turns out. We are basically doing the same thing but backwards. I plan on doing s52 pistons when my engine gives.
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Hot stuff. Keep us updated :D
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2002maniac has done my pistons and I too am using the M44 crank. After much debate about the quality of the semi-counterweighted crank I will be suing it since I have the stuff and money is tight. I have a set of used M44 rods coming and M44 valves, as well as some lighter piston pins that weigh 85 grams and not 108 grams like the stock pins. I will be using a 1.5mm head gasket so the CR will be around 10.5:1. We shall see how this works out.
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Sounds like a good budget build. Nice work.
With no knock sensor, you sure you don't want to up it to 11:1?:p
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Dino, What's your source for the lighter pins? Aftermarket or OE from some other car? I also need the link to the company that has the AEG lifters for $130. The best price I can find so far is like $10 each.
Thanks.
I also ordered some Grade 12.1 head bolts from Boltdepot.com
They are only 90mm rather than the stock 95mm but we'll see what happens.
When I was measuring the thread pitch on the old stretch bolts I was shocked by how much they had stretched.
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Sounds like a good budget build. Nice work.
With no knock sensor, you sure you don't want to up it to 11:1?:p
It really wouldnt worry me a bit with good tuning. I've been looking into megasquirt and it's capabilities of running COP's
Megasquirt is VERY impressive as far as features go, and online support is almost endless.
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The lifters are here fourseasontuning.com
And the wrist pins are from top end performance they have a few different options but the ones I will be opting for are cheap and lighter than stock. Oh by the way I will be using the M44 crank, 2002maniac. I dont have money for what I would realy like to build, so the M44 will have to do until I get a bunch of money. I am hoping for 175hp crank
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whats the story on the lifters???
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The stock BMW M42 lifters weigh 74grams each and the VW lifters from the AEG engine weigh 48 grams each go to fourseasonstuning.com and look at there oem engine parts.
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whats the story on the lifters???
it also looks like the AEG lifters hold less oil so they will be even lighter when you compare the weights of each lifter pumped up with oil.
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i thouht holding more oil was better for high rpm? has anyone actually used or test fit them? whats the redline of the engine they come from? they are much cheaper then bmw lifters but that could be a bad thing
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16v volkswagen guys use them over 8krpm
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Yeah, I second the first idea for doing this. Getting an M47 crank is tough, and there is some hard machining that needs doing. Let's see if we can come up with some sort of home-brew solution, that is nice & reputable as well!
Does anyone have any ideas on this yet?
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Thanks.
I also ordered some Grade 12.1 head bolts from Boltdepot.com
They are only 90mm rather than the stock 95mm but we'll see what happens.
When I was measuring the thread pitch on the old stretch bolts I was shocked by how much they had stretched.
I see no reason for upgrading the headbolts on the M42 if natually aspirated. Actually the S42(1995) engine used stock headbolts, as well as main bearing bolts. I would be more concerned about using extra high quality rod bolts.
Also i'm not an engineer, but your remarks about the stretch on the bolts makes me think that they have been over tightened. And not of too low specification for the application.
modern stretch bolts should be considered like a spring, a very stiff one too. When tightening the bolt you typically tighten it to abut 80% of it's yeild strength. Thereby stretching the bolt / tensioning the spring. If you tighten it above the yeild strength of the bolt. You will see permanent stretch (not good) as the clamping force has then been compromised. And the metal structure distorted, resulting in a weakened bolt thats ready to be scraped.
Very high quality fasteners are often precission measured and logged before assembly. And during rebuilds checked against the log, any sign of permanent stretch means the bolt has to be replaced.
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is the oil chanel in the lifters in the same place as the bmw lifters?
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Why do not solid lifters if you want to rev it up?
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im using m50 lifters because they hold more oil and swap right in :)
Also, 2002maniac, you do machine work? can you clean up my s50 pistons?
Thanks,
Denis
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Why do not solid lifters if you want to rev it up?
$$$
The main reason I wanted to upgrade the headbolts is becuase there is a chance I'll have the head on and off a few times and I dont want to buy new stretch bolts each time.
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Also, 2002maniac, you do machine work? can you clean up my s50 pistons?
What needs to be done to them? One-off parts can require alot of time to get the setup and programming just right so it could get expensive.
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fourseasonstuning.com and look at there oem engine parts.
The guy who owns Four Season is an old friend of mine. I used to own a VW. Perhaps I can setup a discount with him for M42/R3V guys...His prices are always reasonable and he works with you to get the best prices. He's a one-man deal, so no customer service hassles.