m90 stroker

[navytapaul]

I've been researching doing this and would like to have some feedback on a setup I've been thinking about putting together.

m90 block
vw 94 pistons
b35 crankshaft and rods
b35 rebuilt head with minor work
IE headers
either a bananafold with 1.3 conversion or b35 manifold
miller maf and chip
2.5" catless exhaust with 02
mls 1.7 head gasket
arp studs

I'm pretty sure this should yeild a nice stroker motor hopefully around the 220 range? It's very possible I'm wrong. As I said earlier, any feedback would be greatly appreciated.

Thanks,

Paul

[pantelones]

http://forums.bimmerforums.com/forum/showthread.php?1952450-M30-vs-M90&p=25900755#post25900755

Interesting... Was unaware of another m30 variant.

My only knowledgeable critique that I'm sure others will note is to ditch the Miller MAF and run Mega-Squirt... Same cost but much, much more tuning capabilities with MS and both will need dyno time to dial them in. Also a wide-band o2 sensor is always a good idea when playing around with tuning.

With that being said, is there any particular reason why you want to run the Miller system?

[navytapaul]

very informative link, thanks.

no reason really on the miller maf, I've been considering MS especially a diypnp since I already have a harness made. I forgot about a wideband too, definitely need one.

[Jb325is]

This is pretty much what I'm running in my e30 but I am using m90 pistons and running megasquirt. Mine makes 220whp, maybe more now but I haven't had it on the dyno in a little while.

[navytapaul]

What all do you have done if you don't mind me asking?

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[Jb325is]

My engine is a b35 block, bored for m90 pistons, b35 crank/rods. Megasquirt, stahl long tubes with no cats, head ported a bit, valve job and that's it. It's fantastic to drive.

[marshallnoise]

Interesting topic. That was a good read too.

Paul, you said VW pistons?

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[navytapaul]

Yeah, 94mm vw air cooled pistons. From what I've read they allow the use of the b35 crank without the risk of damaging the valves when used with the thick head gasket (2.1mm).

Jb, have you had any issues with the block cracking or is that only for boosted applications? Thats really the only reason I haven't considered punching out my b35 block.

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[marshallnoise]

Yeah, 94mm vw air cooled pistons. From what I've read they allow the use of the b35 crank without the risk of damaging the valves when used with the thick head gasket (2.1mm).

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Very interesting. I need to do some reading.

I have a really good friend that is pretty high up at a vintage VW restoration parts house. Shoot me a PM of the part numbers you are looking for and I will give him a call and see what kind of price he can get you.

[Jb325is]

Yeah, 94mm vw air cooled pistons. From what I've read they allow the use of the b35 crank without the risk of damaging the valves when used with the thick head gasket (2.1mm).

Jb, have you had any issues with the block cracking or is that only for boosted applications? Thats really the only reason I haven't considered punching out my b35 block.

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No, I did blow a headgasket between 5 and 6 once but I think that was partly my fault. Forgot to mention my m90 pistons did have valve reliefs cut as well. I think it would be close without them. I'm running the 2.1mm headgasket but my head was decked .3MM. My engine was originially in an e34, so the b35 block was used to retain the stock motor mounts since the mounting bosses are different for the m90/b34

I will admit that I'm considering pulling my motor and going with an s38 or s54. Even with the 290 cam, I don't like the lack of high end power. I drive an e34 m5 every day and although my e30 is much faster I definitely favor the powerband of the s38

[navytapaul]

Marshall, I'm gonna have to get those. As soon as I plan this all out to do it the right way I'm going to pull the trigger on all of it.

Jb, what's the s38 powerband like? I've been considering using my b35 block, the only apprehension being the possible cracking, but now I think I'll just use it since it's already in the car. After doing more research than my brain can handle, I read that there should be .003mm of clearance between the piston and the cylinder wall to avoid piston slap, do you agree with this? If I didn't deck the head, how would that affect the compression ratio?

[LJ851]

My buddy built a vw piston M90 w/b35 crank but has not run it yet, it's still on a stand. I remember the pistons protruding past the deck a bit and valve to piston being pretty tight. Not a stock cam though...

[Jb325is]

Marshall, I'm gonna have to get those. As soon as I plan this all out to do it the right way I'm going to pull the trigger on all of it.

Jb, what's the s38 powerband like? I've been considering using my b35 block, the only apprehension being the possible cracking, but now I think I'll just use it since it's already in the car. After doing more research than my brain can handle, I read that there should be .003mm of clearance between the piston and the cylinder wall to avoid piston slap, do you agree with this? If I didn't deck the head, how would that affect the compression ratio?

s38 pulls very hard all the way up 7k, m30 runs out of steam around 6k, but has a lot more low end torque. I've never heard on an m30 block cracking. There are tons of people running turbo m30's with everything stock except some ARP studs and a MLS gasket. I wouldn't worry about it at all. As far as clearance, no idea, but if you gave your pistons/rings and block to any competent engine builder/machinist I would think they would know what to do. You only need to deck the head if it needs it, and the amount we are talking about here is going to be negligible.

LJ851 knows way more than I do about this stuff \/

My buddy built a vw piston M90 w/b35 crank but has not run it yet, it's still on a stand. I remember the pistons protruding past the deck a bit and valve to piston being pretty tight. Not a stock cam though...

Yeah I forgot to add my cam is not stock, but I still don't know any of the dimensions on it either so not really worth mentioning

[navytapaul]

I'm leaning more towards the b35 block with vw pistons now, wouldn't be really a stroker anymore but should be 3.6 if not close to it.

supposedly they can be picked up pretty cheap here http://www.lowbugget.com/Mahle.html

[slammin.e28]

B34 and B35 blocks have the same bore and stroke.

M90 cam is the same profile as B35 cam.