m50 swap, s50

[sjle11789]

ive got the engine, diff, and ecu. keeping the stock 5 speed. is there anything at all that could need modification? sensors and such? the stock m50 is from a 94 325i and the s50 is from a 95 m3 us. will the 325 wiring harness be sufficient or will i need to replace it with an m3's?

also does anyone know where i can go about finding some good stock or oversize pistons for the s50?

thanks.

[dinaneurobmw]

if u have single vanos then its an m50tu the wire harness will switch over to the s50. both engine heads will have the same number of coolant temp sensors in the head (s52 has 1 and s50 has 2, or vise versa cant remember exactly) I'm also not 100% sure if the s50 dme will plug into the 325 harness but if it dosnt u can still use your 325 harness and ur 325 dme just get it chiped for an s50 (u have to open up the dme to replace the chip and it pushes right into the circuit board) other than that the motor mounts will line up the engine for both engines the same. im also not sure if the trans is going to have a problem lining up with the m3 flywheel since if i remember right the splines are bigger on the s50 clutch disc and the input shaft of the trans is bigger.The drive shaft length may change since ur not using the m3 trans so one might be shorter or longer or splined differant? I havent checked any where else for pistons except for the dealer and piston and rings run at least $1,500 but they have the option to goes all the way to .060" over. Just FYI ive only done this swap with a 93 325 and an s52 engine, trans, driveshaft and complete rear end with subframe and diff/axles...*IMPORTANT!!!!! If u dont weld in the re-enforcement plates on the body where the rear subframe bolts into the body then u will rip out the body mounts and u will be in a world of hurt... turner has them i think and so dose the dealer but u have to look up an m3 for the part you need... the real m3's have them istalled when they are made from the factory for a reason