Piano top pistons in a CSi??

[Ed G]

Anyone know if piano top pistons are std in a CSi? Just dismantled the head from an engine that was in my parts car and that's what turned up. Haven't pulled them out yet, nor do I have a need...I'm just curious if PO did any mods. The engine's definitely been disassembled before.

TIA

 

[Bill Riblett]

Yes

BMW determined compression ratios on M30 motors with different piston tops. CSi s came with 9.5:1 compression ratios and so-called piano tops.