trevore928

Hey everyone,

I was wondering if anyone has swapped a 928 S4 Motor like an m28/41 or m28/42 into an earlier model 928 S such as an '85 with a 32 valve/44 m28/44. What would need to be changed on the early car to fit/run the newer motor?
Thanks

-Trevor

davek9

The motor would "fit" right in, however the ECU's and Engine wiring harness are totally different (flappy control, Hall sensor, knock sensors), would most likely need to change the CE panel and maybe even dash wiring.

Why not just use the simply "superior" S3 engine and hop it up, what is your end goal?

Dave K

trevore928

My S3 motor has tons of issues and as a result I am replacing the entire thing. I'm most likely going to just use another 32 valve S3 motor, I was just curious what would need to be done to use a later model motor. I would much rather find an M28/21 euro engine, but theyre pretty hard to find.

Thanks
-Trevor

soontobered84

Even swapping in a M28/21 16 valve engine would require a crapload of electrical work and computer adjustments. An S3 engine swap should be easier to swap and probably cheaper and easier to find one.

Mikebte

Do you have a parts car your swapping everything from or are you getting an engine and doing the wiring as you go?
I have found engine swaps to be a lot easier when you have the donor car side by side.

Ducman82

Repair the S3.... or you will have to do re wiring of the CE for an S4. Going to an early 16v would be going backwards and WAY more work than it's worth. I did the wiring change for an S4 motor in a 84. Complete front of car harness (you need that for fans) adding fuses, and re doing the CE wiring. Depends how much work you want to do. Why not repair the awesome S3 motor? Be cheaper

Edward928

This is my 1985 S with the S4 engine and S4 5-speed. Yeah talk about a pain in the butt, everything runs alright. I put a new S4 engine harness since the old one was a hack job.
I have a S3 engine in my parts car, so if it ever goes south, my replacement will bring it back to stock.