M20b27 Different compression ratios

[skitzy777]

Im in the process of planning an m20 2.7 stroker.

I was going to source an eta bottom end, rebuild the bottom end and bolt it onto my existing 731 head with the basic motronic 1.3 wiring, afm, ecu, fuel system, and all that.

Ive been looking on the m20 wikipedia and there are a whole load of different m20b27 engines with different power and compression, with the compression part being the most interesting to me.

My question is how would i know what b27 im buying has what compression bottom end, and since the 731 head and the 200 head have the same volume in the combustion chamber it wouldnt change the compression would it?

Thank you :D

[digger]

there are 3 types (exc SETA which is not relevant for your application) 9:1, 10.2:1 and 11:1. the ones in a 325e are 9:1

the ones is the 5 series etc will be different compression e.g. 525e/528e depending on the year etc

visually the pistons will be dish depth vs dome



731 and 200 head have same volume combustion chamber so same CR

[skitzy777]

This is exactly what i was looking for, time to find a wrecking 1983-85 525e

[digger]

Check eBay uk or U.K. Forums