996TT External Wastegate Project Exposed

We were trying to think of some different ways to gain HP over the traditional methods. One thing we have done on some of our STI and EVO cars we have built is to close the factory internal wastegate and run an external Tial 38mm wastegate. Why do this? The factory wastegate is restrictive and the flow of air is not able to be maximized. When you start increasing boost and going for more power, you can gain more HP by going to an external setup. As tested and proven on other cars, the external wastegate setup made 20-30HP on the dyno to the wheels So…. Why the hell not right.

To prototype this setup for Agency Power, we took a set of headers from GHL, 2 Tial 38mm wastegates with 1.0bar springs, and connected the dots. With a quick fab job, we attached the necessary vacuum lines and throw it on the dyno . Before running the car we reset the ECU and then went for it.

What went right and what did not… The car was only making about 12psi so the spring in the wastegate was to soft. Even though it was a 1bar spring, it was making a little less which is about normal. so we have a new spring coming tomorrow. We threw a manual boost controller on the car, but because the ECU was noticing more air being introduced, it would close the throttle plate. So the good thing is that on 12PSI 2 PSI less then our before dyno, we made the same HP and TQ about. 450 and 490. So once we have the new spring in and make about 1.0-1.2 bar. We should be making that extra 20-30WHP that external gates create. Another cool thing about this setup is the boost is almost instant, takes away some lag and really makes for a fun car to drive. Because of the difference in pressure, the AP BOV is much louder.

So sound clips, new dyno charts, and info are all coming soon. Here are some pics. More pics can be found at www.myvividracing.com/gallery

The production model will be very similar. Should cost around $1995. For 20-30HP, not bad