S4 NA rotors into S4 TII engine q's (searched)
 

Going to be rebuilding my S4 TII engine here pretty quick, and I had a couple quick questions.

The engine will be streetported, fairly largely. For now, the turbo will stay stock, with close to stock boost levels. Eventually a small hybrid will be used, but I'm going to keep it small since this car is mostly a DD/autox car. Tuning will be done with an SAFC, and secondary injectors will probably be upgraded to 720cc.

I have a set of S4 NA rotors that I'm considering putting in. Reason being, since this car will be an autox car, I wonder if using the higher compression rotors will give a little more power down low, since the street port will probably take away some low-end grunt.

I realize tuning will be very important, but any other thoughts/issues you guys have?

Yeah, you'll be OK, the difference isn't very large, so it's not all too bad, especially for the levels you plan to run. Just run it a little bit richer and you'll be ok, also you'll be able to make more power at lower boost levels, so keep that in mind when cranking it up.

might want to balance the rotating assembly seeing you are using a different eccentric with different rotors...but not sure how bad it would really be...

All e-shafts are the same.. just make sure you use a S4 front counterweight with a S4 TII flywheel. That will keep it balanced

So are you saying to use the counterweight off the NA, or the TII?

Front counterweights are identical between N/A and TII ofthe same series.
You would need to use a TII S4 flywheel.

Ah, gotcha. So basically, just use everything off my current TII motor, and swap rotors.

I'm running s4 N/A rotors in my s4 TII with slightly extended RB street-ports (pretty big).

Since doing the rebuild nearly 4000k miles ago, I've had no problems whatsoever. I've set my MBC so that max boost is at 10psi on the stock turbo (ported WG), stock IC, and stock fuel (cleaned 550cc's) etc.

I don't notice a huge difference, but I'm sure it helps a little on the DL.

Wow, 4,000,000 miles since the last rebuild???
4 million miles???
Sorry, I couldn't resist. :)


-Ted

i plan to use a set of 85 gsl se rotors in an 88 t2 (stock 3 mm apex seals high compression) run water injection and 15 psi
shooting for 350 whp

haha... shaddup, lol.