Engine swap question (2.7l to 2.5l)

[KMOSES]

I'm swapping out my 2.7l ETA engine for 2.5l but keeping the ETA transmission. What flywheel, clutch and pressure plate assembly will I need to make this work? Also, would a 3.73 differential be the one to use?

[2.5-12]

you can use the same FW, clutch, pp, tob, trans, drive shaft, diff.

the 3.73 is actually, I think, the best diff for the B25 and the Getrag 260. I'm amazed your 2.7 car came with anything over a 2.93 or a 3.25.

[KMOSES]

I thought the 2.7 flywheel was too heavy for a 2.5 engine and that was the reason for my post. My '87 ETA did come with a 2.93 diff. but I am using a '87 325i convertible as a donor car it has the 2.5l and 3.73 diff. The '87 vert has a bad case of body cancer.

[E30Gus]

I am doing the same in a couple weeks. I was told to go with a 325i single mass FW and associated clutch/PP. Depending on your year eta you have either a dual mass or single mass FW. Also if you do change the FW I believe you have to get the correct starter to line up with the new FW, or change the gear part on the end of the starter. Double check on that though.
The stock diff in a 325i is the 3.73 (4.10 automatic/ix?) so you would want to get the taller gear in the back because the 325i with the 2.93 (probably what you have) in the rear will be fairly slow.

[jlevie]

I'd switch to the M20B25 flywheel as it is lighter. Use a matching pressure plate. clutch disk, & throwout bearing. It would probably be a good idea to also replace the pilot bearing.

[E30Gus]

I'd switch to the M20B25 flywheel as it is lighter. Use a matching pressure plate. clutch disk, & throwout bearing. It would probably be a good idea to also replace the pilot bearing.

^ The man!

[2.5-12]

yes, the single mass later 325e and 325i flywheel/clutch/pp is better BUT you asked if what you had would work and of course the dual-mass setup would work on the B25.

[Bmwmotorm52]

Sorry notin trying to take over your thread,but im doing a auto to manual swapand i want to know what is my diff ratio?(88 325is)

[2.5-12]

Sorry notin trying to take over your thread,but im doing a auto to manual swapand i want to know what is my diff ratio?(88 325is)

likely a 4.10LSD