M20 stroker motor with M52 crankshaft...?

[fastpat]

I found a reference to this mod on the e30Tech.com forum and wondered if anyone has completed an engine with this part?

The M52 has a 84mm stroke, a nice increase over the 81mm eta crank, and it's a forged part. Might be expensive and require some looking, both downsides.

Reference: M20 Stroker FAQ.

[jmc1590]

I can remember reading through that in my search for information. A couple of items that are pertinent to the M52 crank:

• You will need a spacer machined to properly fit in the M20 block.

• When matched with the 130mm eta rods, the "i" piston is almost a perfect match to the 885 head. (Sits about .5mm low.)

• Some additional machining may be required based on piston selection. May need crank & pistons clearanced.

It does net a reasonable 2.8 liter build. May have to try this in the future.

[ealinn]

m52 cranks are not expensive or hard to find, bought a short block for $100.

[fastpat]

m52 cranks are not expensive or hard to find, bought a short block for $100.

Hmmm, that's reasonable. Looks like you could do custom pistons and add a M52 crank and come up with almost 3 liters displacement for less than $1000 in parts (not counting the "while you're in there" stuff). I like that idea.

[Bimmerguy2002]

There is another crank you can use out of an e36.

At any rate, m30b35 it, then modify that if you arent going forced induction; granted you can find a tranny on the cheap.

He who builds m20s will reap the rewards of a lighter wallet-Confucious 21 AD

[fastpat]

There is another crank you can use out of an e36.

At any rate, m30b35 it, then modify that if you arent going forced induction; granted you can find a tranny on the cheap.

He who builds m20s will reap the rewards of a lighter wallet-Confucious 21 AD

I have a 325i Cab with the M20 engine, not my e28 which is a 535is.

No forced induction, thanks!

[turbodan]

It doesn't really matter which motor you use, the car is going to be slow either way unless you want to turbocharge it. For those in California, that sucks.

[Lucas_Roehr]

seems like at that rate you may as well just use an M50 or an M52. Dont the m20 and the m50 have close enough design/ shape to bolt to the same style bell housing? and wont the m50 fit in the e30 compartment with very little modification? Start with an engine that breaths better. Two cams is better than one!

[klrskies]

I was involved in several threads on e30tech regarding the stroked M20 engine. The 84 mm crank/ eta rod/"i" piston are a good set up although the rod ratio is extremely short. I would consider larger diameter, custom, light, forged pistons.

I always felt I'd rather put money and effort into an m30 engine if I wanted to mod a 2 valve BMW engine. The M20's small valve size and sharp port bend just prior to the inlet valve , and it's long, second reflection intake manifold both put a serious cap on normally aspirated capability. Turboing being the exception.

The 4 valve engines are the way to go these days if you seek N/A high performance. The m20 and m30 are designed to to make good torque at moderate rpm levels. Revising that design requires substantial wallet thickness & will never compare to a 4 valve, varible valve timing engine.

regards,
Ken