m20b25 Euro Pistons - 9.7:1 CR | Worthy upgrade for a hot 2.5L?

[bimma360]

So I searched, but couldn't really find any talk about using the Euro i piston's for the higher CR. I'm sure this has been discussed to some length before, so if anyone can point in the right direction of the info that would be greatly appreciated.

Anyway, stroker talk aside I was curious as to why this isn't mentioned more often. Might even be the idea that if you are in the motor already you might as well build a stroker.

So strictly speaking of a hot 2.5L...

I know the power difference between the euro b25's and the US b25's is small. But I wonder if a euro spec'd motor will react better to things like intake, BBTB, cam, injectors, headers, exhaust, and a tune (among other things).

I feel like a 9.7:1 CR vs an 8.8:1 CR is pretty significant. Am I wrong?

And I know this is a very specific question, but does anyone know the weight of the euro piston?

[bimma360]

Actually, now seeing that the late model euro pistons also got the "weight reduction" treatment like the US late models pistons did... A better question is, what is the weight difference between the late model euro and the late model US?

[Dirtboy]

Not to threadjack, but learn something new everyday...

I've got a euro spec e30 that I just imported and I never knew the CR was different between US and Euro. I KNEW I should have put a cam in while rebuilding the engine... :roll:

[sweet6e30]

werd

[jlevie]

Yes, the higher compression ratio pistons would yield more power. But only if you modify the tune to increase the timing advance and tweak the fuel maps.

[mach schnell]

Was the Euro compression 9.7:1 on all Euro 325i’s? Or was it for a certain year period, or what? I have a March1988-built 325i Touring, curious what the compression actually is.

[ADEN]

They are 10mm taller than the us (apparently not lighter than us) and what raised the comp. Is .23mm higher crown, i think the higher comp. is due to them running catless.

https://www.e30zone.net/e30wiki/index.php/M20

[digger]

Was the Euro compression 9.7:1 on all Euro 325i’s? Or was it for a certain year period, or what? I have a March1988-built 325i Touring, curious what the compression actually is.

only the early ones like 1985/86. Your 88 is a 8.8:1 does it have an engine code on the block e.g 25 6xx?