3L crank into M52B28 alloy block.

[Drew325is]

I read somewhere in the 35 page E30 twin cam swap thread that putting the 3L US M3 crank into the M52B28 alloy block, using the M52B28 pistons works a treat on the street. Has anyone actually done this?

If I were going to do it it'd go something like this:
Core engine = M52B28
M50 intake manifold
US M3 or Schrick cams
3L US M3 crank
M52B28 piston shaved to correct compression

Does that sound like a good idea?

[carazy]

my research in to this idea found the following:
You need to bore out the block at bit and fit the m3 rods and crank with some custom pistons.. far easier to simply fit the m3 block if you can get one.

[Drew325is]

Ah...these things are often over-simplified!

Boring out my alloy block would be a costly job, as it'd need re-sleeving. Think I'll give it a miss!

[Stu]

Drew, No, you've got it exactly right! Retaining the 84mm bore of the 2.8 alloy block is fine. Keep the nice graphite coated pistons that come in that motor. Use the 3.0 crankshaft, and mill the pistons to about 11:1 (works awesome on a street motor, assuming you can get good gas, 93oct by US specs).

My dad ran that setup in his E30 M3. With M3 camshafts, a worked head, Euro MAF and chip...it ran just as well as my 3.0 235whp motor.

[Drew325is]

Interesting...so obviously the only thing the 3L crank can do is lengthen the stroke right? So does it actually achieve a capacity of 3L? I'm assuming the S50B30 has a larger bore than the M52B28? Just wondering what the math is?

[Stu]

Interesting...so obviously the only thing the 3L crank can do is lengthen the stroke right? So does it actually achieve a capacity of 3L? I'm assuming the S50B30 has a larger bore than the M52B28? Just wondering what the math is?

85.8 stroke of the 3.0 crank and the 86mm bore gives you about a 2860cc--2.9L. You have to go 86+ on the pistons to get 3.0/3.2.

Your 2.8 will absolutely insane midrange with this setup, and still howl to 7000 (I've seen this motor go 7500 w/o probs)

[Tony S]

What about using hte 3.2 crank shaft

[Addissimo]

3.2 cankshaft = 3.1l motor with standard bore...

eric really needs to get his site up again... it has all this info

[Tony S]

would you need special pistons with the 3.2 crank

[carazy]

So the only thing you need to do when fitting the 3.0l crank is shave the pistons down a bit is that correct?
If so I may go hunting for an m3 crank as well :-)

[chuck90m3]

just a quick tip, if you are looking for a 3.2L crank, the E36 3.2L and the 3,5,X,Z, 3.0L have the same crank. Try finding a shop that has had a customer with a E46 330 where the headbolts have pulled from the block. Once they replace the bottom end and have no use for the old one offer to take it off for them, (aluminum recycle) and use the crank.

[JPStrniste]

this looks like it might turn into a longer thread....


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[JPStrniste]

So a 3.0L or a 3.2L crank will fit in the M52 alloy block and the only thing you should do is shave the pistons to 11:1 compression?

I've already converted to OBD 1 and have s50 cams installed. I still havent driven the car yet, but this would significantly increase the performance of the motor too?

are there any websites with a full write up on this swap? any other machine work that "should" be done?

[chuck90m3]

So a 3.0L or a 3.2L crank will fit in the M52 alloy block and the only thing you should do is shave the pistons to 11:1 compression?

I've already converted to OBD 1 and have s50 cams installed. I still havent driven the car yet, but this would significantly increase the performance of the motor too?

are there any websites with a full write up on this swap? any other machine work that "should" be done?

Correct either crank will work using the NON Vanos connecting rods and milling the pistons.

I have not seen any websites with write ups. I talked with Alex and Stu in the past as well as there father Pete on this topic. If you are interested in this setup i would recommend contacting Pete at Precision Performance in SC. As far as I understand he is the one who engineered this arrangement of parts so he should be able to tell you what to do for parts, machining, and software issues.

[JPStrniste]

Wow, That's Great!!

So you're thinking I need non-vanos connecting rods? that works out well for me because i have a non vanos m50 sitting in my shed..... lucky me.

I will contact them about this though. Thanks for the info. and I'll tell them you recommended me to them.