KenK in TX

3.0A4muletRED is asking about doing a custom exhaust in the performance forum, so I pointed out that he needs to be aware of those variable valves. Now the curiosity is killing me - I'm just wondering where they are placed in the system.

woofpup

Do you mean the solenoid valve for camshaft adjustment on the exhaust?

EdP

is the intake manifold which is a 3 way tuned runner.

KenK in TX

...an exhaust valve that manipulated backpressure to give you torque at low rpms (closed) or free flow at high rpms (open).

Yamaha introduced this on the FZR (I think) back in the late 80's - its called the EXUP Valve and has actually been proven on a dyno and hard to match the performance with just a tuned exhaust system.

Pretty nifty stuff, and it didnt suprise me in the least when I saw how much work went into the tuned 3.0 headers - very impressive.

So was he full of it?

EdP

news to me. My Yammy had that, but Audi's do not in the exhaust path.

April

I've not heard that either. The variable timing and intake have been around a while.

woofpup

Yeah, I think he's thinking of the variable intake, not exhaust.

April

I remember driving around in an A8 with my head out the window, trying to hear the changeover;-)

Nefilim

I think starting with the E46, the valve is in one of the twin exhaust tips, clearly visible from the rear.

KenK in TX

Thanks for the facts, Ed!