Megasquirt tuning maps question

tcolt · Post by **tcolt** » Sun Oct 11, 2015 6:41 pm

I trust Farah, but from my recollection, my 3.0CSi had piano top pistons and the b34 had flat top pistons. It definitely didn't have dished or domed pistons or any valve cut-outs. I personally bought and installed the engine from a low mileage German 1984 735i in 1989. There might have been different versions of that b34 engine? I know that there were changes made in the Motronic between early 1980s and mid 1980s before the US ever offered the b34 engine in 1985.

CabbageFumes · Post by **CabbageFumes** » Sun Oct 11, 2015 7:27 pm

tcolt wrote:I trust Farah, but from my recollection, my 3.0CSi had piano top pistons and the b34 had flat top pistons. It definitely didn't have dished or domed pistons or any valve cut-outs. I personally bought and installed the engine from a low mileage German 1984 735i in 1989. There might have been different versions of that b34 engine? I know that there were changes made in the Motronic between early 1980s and mid 1980s before the US ever offered the b34 engine in 1985.

I am absolutely positive that there is no such thing as a flat top piston in any b34 of any flavor ever produced. All 3.5L engines are either b34 or b35 pictured above unless turbo'd, which has dished pistons like the Green engines.