What are the differences bewteen s4 and s5 na motors, besides rotors and ports maby?? and what would be needed to swap from s4 to s5 ? Last would it be feasible to get t2 rotor housings and streetport them and run on street ?? in an na motor??

 

Please do a search for the S4 to S5 swap, even check out the FAQ.

Not sure why you would want T2 housings to run on an NA. If you did that you would need a new intake manifold, yads yada. A lot of work.

 

OK.
1. S4 and S5 n/a's have different compression ratios because of the rotors. Also they have diffferent intake manifolds and the S4 has a mechanical Oil Metering Pump and the S5's is electronic.

2. To swap a S4 to S5 motor would be (in my opinion) a waste of money. U can swap the S5 rotors and manifold onto a S4 w/ slight modification. Then w/ porting would see good hp gains.

3. Putting in TII housings would change it to a 4 port design and I'm not sure if it would even work. The TII's are a 4 port motor unlike the n/a which has 6 ports, the extra 2 open at 3800rpm.

 

basically lighter rotors and higher compression. also, the way the 5th and 6th ports open are different. on the S4's there is a sensor or vaccuum tube that opens the ports only when there is 2 psi of back pressure (i think). this means if you put a largely free flowing exhaust then you wont be able to open up your extra ports, and will lose all your top end power. there is a cheap solution to this so you dont have to worry too much about it. there were numerous other improvements made to the S5 motor that made it more relaible and hassle free. (unflooding process is easier and built in pulsation dampner)

 

look at icemark's thread about going back to non-turbo. he built an s4/s5 hybrid motor that gets the best of both worlds while keeping things simple. sjould answer most of your questions.