Hello guys,

I just bought 2 FC S4 NA's and want to build one with a stock S4 engine, emissions removed, simplified engine bay, racing beat header and straight pipes.
The car should be very basic engine wise as it will be my training/missile car, low powered cars = much fun

I sure want to have my 5th and 6th port actuating as it should, nowing that the S4 engines need backpressure from the exhaust system to actuate I started to look around in the forum.
Then I realized that my system looks totally different to what you guys are used to. Here is a comparrison:

EUDM



USDM



So it seems that my actuators are working with vacuum instead of your actuators which need about 2psi of pressure to actuate.
So, do I need exhaust backpressure un my EUDM system? Or does it take vacuum "itself" from before the throttle body trough the stock rats nest, actuated by an solenoid?

Thanks in advance for your help!

 

Ask Meercat, he has that same setup and can help you out.

 

Well, the diagram shows the edm one is only vacuum....so id take a gander and say you don't need the exhaust for actuating