When getting my T2 block rebuilt, I was considering going with S4 N/A rotors. I figure it will give me a bit more power, and quicker spool, as well as allow for more power with less boost. Is anyone running a similar setup? Will the S4 T2 ECU be able to deal with this, since it is almost a full point higher than the stock CR. 9.4:1 still isnt all that high compression, I figure I should still be fine with pump gas and 10-12 PSI. Just looking for suggestions, or people running similar setups.

 

 

i am running s4 NA rotors in my S4 tII. just built it. i have about 3k miles on it so far. it is SWEET. it is damn near as fast as my old modded NA off boost, and way fast on boost. it spools real quick. i have run 87 octane at 6psi with no problems, but am running 89 now, and will continue to do so. i expect to max at 12 psi. my afr is still decent...actually it is too rich. i will be going to safc or standalone this summer, as well as upgraded turbo. anyway..go for it man...its a great setup.

pat

 

We don't recommend this, especially on a stock ECU.


-Ted

 

Ill most likely be going stadalone (Haltech), will it be safer/easier to control with this? Im going to make a call to the place that will be tuning it as well, so see what they have to say.

 

Stand-alone EMS control over ignition timing is not a problem in this case...


-Ted

 

Cool..thanks TED.
Have you guys ever built an engine like this..and if so, what were your impressions?

 

No, not yet, but hIGGI has been pushing me to built such an engine.

Power down low should be signficantly more responsive, but I worry about the top end power safety under lots of boost.


-Ted

 

Because of the high compression rotors this could be a problem.. but it CAN be done.
I would assume that running 6-8 psi on N/A rotors should be comparable to 12-14 psi on T2 rotors. Correct?

Remember, i've always just been an N/A guy, i'm still learning all this as i go along.

 

when i was researching this, i came across someone who had done it and compared to stock... the hp curves cross at about 14-16 psi. that is..the low compression makes more power over 14-16, and the high makes more under that level. since i did not want a high boost car, and wanted good driveability, I went with the high compression.

Effective compression= enigne compression+ boost (psi)/2

So, on my car at 8 psi (what im running now):

9.4 + 4 = 13.4:1

the person i talked to had run 17 psi on his NA rotored TII with no problems.

While it may not be recommended by some, those of us who have done it beg to differ.

pat

 

we are in process of building such engine now S4 TII block, ported with S4 NA rotors.

since we had some leftover 3mm apex seals, we decided to to try them in this engine, so S4 NA rotors will be machined to 3mm

its considered like experiment, on stock S4 TII ECU

wastegate is heavily ported (34mm, new flapper) so we should be able to keep boost down in safe levels....

will let u know (might take few more months or years to have it all done ;o)))

 

Cool, I think Im giong to do it as well. My turbo is a TO4B hybrid S5, with the stock wastegate ported and open-vented. Engine will have a fairly sized streetport. Alls I want is 300rwhp with good realiability.. I figure S5 T2s and FDs use 9:1 CR rotors, with no problems. .4 more isnt all that big of a deal. I agree the stock ECU may have some issues, but like I said Ill most likely be going haltech, so that shouldnt be an issue.

 

well in our case we wants to have more than 100 horses and car which will run ;o)