I have an s5 TII and i want to run an rtek 2.1 ecu. My question is if it is possible to run an s4 ecu and wiring harness on an s5 turboII motor.
If not, could i use an s4 TII motor,wiring harness and ecu and retain the s5 turbo?
I am only proposing doing this because i need a new motor and mine is not rebuild able as i blew my motor over a year ago and coolant has been sitting in it since then...damn coolant seals.

 

Have you really determined that the engine is not rebuildable? Blowing a coolant seal isnt nearly as bad as blowing apex seals. have you cracked the block open?

If you want to use rtek2 you could wait a bit, they are very close into releasing S5TII Rtek2.0 pending the feedback from the beta testers. It would cut your work load by a large percentage.

 

I'm not sure about wiring up a s5 motor as an s4 but I have a s4 motor with s5 turbo, manifold with S4 oil and coolant lines

 

leave the wiring all within the same series. its a pain in the *** to mix and match. if anything, get an s4 short block and use s5 everything else.

 

change the frong oil cover to a s4 one and use the s4 tii wiring harness.