Author Topic: e30 318i pistons in m42??? (Read 3388 times)

keggy · « **on:** December 29, 2007, 08:19:17 AM »

hey guys i heard one time that puting 318i m40 pistons into a m42 engine would lower the comp ratio does anyone know if this is true?

Abrax · « **Reply #1 on:** December 29, 2007, 08:34:47 AM »

As this is the same bore and block and displacement - I think about M40 compression... It would be 9:1 ? May differ a little because of different combustion chamber volume.

m44power · « **Reply #2 on:** December 29, 2007, 08:59:26 PM »

there are different they dont have valve pockets

Abrax · « **Reply #3 on:** January 01, 2008, 10:23:28 AM »

Quote from: m44power;40151

there are different they dont have valve pockets

Right, but M40 pistons are little lower, so they don't have the collision when the m42 head is put on. So it is possible to put them in, but You will get lower C/R.

If You want I can take some pictures...

keggy · « **Reply #4 on:** January 01, 2008, 01:42:58 PM »

how much will it lower the compression ratio by? was thinkin of a bit of F/I

. has anyone done this? yeh if you can take pics it will be a good help