I am building my engine right now with s5 turbo rotors, and I was curious if the s4 turbo ecu would be dangerous to run. I don't want to have issues caused by the higher compression and i dont know how much different the timing is with the s5 ecu to compensate for the compression. The plan is to eventually upgrade to 720's and run rtek 2.1, but I want to get it running and broke in before I start spending money on performance upgrades. What do you guys think?

 

Anybody have input on this????

 

I had S5 NA rotors in my S4 Turbo engine for last summer, 8K miles on it and had no problems.
As for the ecu, timing is the same, but I think the s5 has a better knock control unit.

 

s5 N/a 9.7 to 1 compression ratio

s4 Turbo 8.5 to 1... CR.

and you're telling people the timing is the same.. happy blown motor...


for the record.. i run s5 N/a rotors in an s4 Turbo engine. on 87 octane! and with stock timing, i didn't get any knock as long as i had 93 octane gas... with 87, i had to retard the timing in all boost areas over 2 psi...before, it knocked real bad..

OP

s5 turbo rotors are 9.0 to 1 CR... you should be fine with a stock ecu and stock boost levels, but you way want use 93 octane for safey's sake.

 

If you guys ran NA rotors I'm just going to assume that my 9.0:1 rotors should be just fine for a little while. Thanks!

 

is not fine for a little while. as long as you have the right afrs and the right timing you will be fine. just dont go all out on the boost thats all

 

Port the waste gate if you have ANY exhaust mods.

 

Timing marks are at 5Degrees, S4 and S5... Or maybe i'm just stupid and the FSM too?

And thank you, but my motor isnt blown.

 

Timing marks don't mean the ECU's run the same timing.......