OK I was searching and couldnt find any thing on this swap. I keep seeing S5 into S4 swaps. Well my motor went on my '90 NA. Well I was contemplenting a rebuild but that would run 2k or so. Well I found someone with a Series 4 13BT, tranny, ECU, harness. Would there be any putting this into my N/A? With having the harness and the ECu there shouldnt be any probs? I know you ask "why put a S4 into a S5?" Well the price is nice for the set, and it has good compression and dosnt leak oil. Plus the S4 could take more boost.
-Stew

 

Actually the S5 can take more boost than an S4, and the S5 has a bigger turbo and lighter rotors. From what I've been told, staying within the same series is best/easiest. I was going to do an S5 T2 conversion on my S4 N/A until I got the opinions of a few "rotary gurus" on the matter. I decided on S4 instead. I'd hold out for an S5 T2 if you could since you're in an S5 already....just my opinion though.

 

White Seven
Thanks for the reply. Holding out for a S5 13BT is harder than you think. =P Just had a good price and thought it could work. It seems it would be more trouble than its worth. Honestly even swapping a S5 13BT into the car seems like a PITA. Just really need my car unning and a N/A rebuild is to much $$ right now. Ugh life sucks!

 

actually the S4 TII engine can hold more boost, because it has less compression...