would there be any reason ans s4 motor trans and rear end wont work in an s5 chassis? im almost 100% that everything will physically fit my main concer is the engine harness and whatnot... i have the s4 engine harness and ecu is there anything i would have to change?? here is the story i have a complete s4 turbo II and the motor is fresh the rear end is fresh and the trans is perfect but there is too much rust on the chassis for my liking so im looking for another butim finding more s5 rollers then s4... any help would be really appeciated

 

Will it physically fit? Absolutely.

Will it be plug and play electrically? Hell no.

You would want to strip the S4 engine down to the block and use an S5 front cover, electric OMP, ECU, MAP sensor, AFM, TPS, TB, and probably go ahead and use S5 manifolds as well.

Trying to get an S4 engine management harness & ECU to work with the S5 body harnesses will not be fun. It can be done, but it's a lot of work, and can lead to some serious problems if mistakes are made.

 

thanks for the info my next question would be is it possible to swap my s4 body harness into an s5 shell??

 

rear end no problem.. S4 and S5 NA , S4 TII and S5 TII ..

 

That's even more work than trying to mate the S4 engine management harness to the S5 front harness.

Note that I said body harnesses. That means the front harness, the engine harness and the rear harness. The front harness in particular wraps around half of the car.

Keep all electronics and wiring harnesses the same series.