Author Topic: S54 pistons to fit in the M42? (Read 3429 times)

M42_Jester · « **on:** December 17, 2008, 06:27:02 PM »

G'Day fellow bimmer heads

i've been looking at a few forums about people that have bored out their M42B18 engine to fit the S50B32 (E36) Euro M3 pistons...but I was wondering if anyone knew whether the S54B32 (from the E46 M3) pistons would fit? The bore is only 0.6mm more than the S50B32, so there shouldn't be a problem...but i'm no mechanic.

Also, any tips on changing from a stock 5-speed manual tranny, to a E36 M3 6-speed manual tranny would be helpful too

Cheers,
Jester

jrobie79 · « **Reply #1 on:** December 20, 2008, 12:56:43 AM »

well i believe jordan over on r3v just threw a 6 speed into his car, i dunno about the pistons, but check out r3v, much more information about that tranny swap imo. it might even be on bimmerforums too, i forget which one i was looking at.

nuvolarossa · « **Reply #2 on:** December 20, 2008, 02:14:07 AM »

you should post this in the builds section

s54 bore is 87mm. metric mechanic use 87mm bore pistons in their kits. You need to know other things to be sure that they will not hit valves, like compression height and more

szed03 · « **Reply #3 on:** December 21, 2008, 07:58:10 PM »

Quote from: nuvolarossa;63249

you should post this in the builds section
s54 bore is 87mm. metric mechanic use 87mm bore pistons in their kits. You need to know other things to be sure that they will not hit valves, like compression height and more

I'm willing to bet that their engines are re-sleeved. Looking at how thin the cylinder walls are on an M42 I'd think that 86mm would already be pushing it.

Anyone on here bore out the stock cylinder sleeves? I'm curious as when it comes time for my build, I was thinking about going with a square bore-to-stroke setup utilizing the stock crank.