m20b25 compression ratio ?

[Mops]

Howdy.

I'm planning custom turbo application for my 1985 e30 325i, but for a start I need to know what I'm working with in terms of stock engine compression.

On the net and other sources I read several different values quoted as to M20B25 stock compression, namely, all the way from 8.2 and 8.5 to 8.7, 9.2 and 9.5. I have original manufacturers manual with my car and according to it, stock engine copression is 9.7:1 -> wich is higher than any other value i found on the internet.

Is there a way to measure compression (or calculate/estimate it somhow), as it is crucial for me to know the correct value, as if i go with too big torbo and boost the engine will pop really quickly...

Thanks in advance,

Mops.

[edited to correcy typos]

[e30_Turbo]

As far as I know, the early type M20B25 are about 9.5-1 and the later engines are 8.5-1, I have the later type so am happy that it's low enough for the boost I plan to run eventually.

So probs so far anyway

Good luck,

Mark.