urs4 seperate wategate exhaust

[gavs20v]

Probably a dafy quaetion
Im looking at getting a 3" turbo back exhaust made up in the next month or so for my 93 urs4 avant. Advice on another thread suggested a seperate wastegate pipe. Would ther be any detrimental effect routing it all the way to the rear of the car instead of exiting out the side towards the front of the car? Id like to keep the anonymity of my slipperwagon as much as possible so was think of having two pairs of twin at the rear similar to the rs4.
Any suggestion?
Cheers
Gav

[Lee]

Route it to the rear of the car....it will be quieter but you will still get a flame show! The blue RS-R avant routed it quite neatly to the rear and it was very discreet. I am sure someone here has a linky.

[Mark Halligan]

Route it to the rear of the car....it will be quieter but you will still get a flame show! The blue RS-R avant routed it quite neatly to the rear and it was very discreet. I am sure someone here has a linky.

Here is the Dahlback one, very nicely done.

[Lee]

Thats the one. Cheers Mark.

[NoNonsense]

Is there a true advantage to giving the wastegate it's own pipe to the rear? Should one have a cat or any silencers on this pipe?

[4WheelDrifter]

A bit more stealth. I thought about this. I guess you'd need a Cat in CA. I'm not sure you'd need a silencer though. Probably depends on personal taste about noise levels. Obviously it would only make a noise at/near full boost.

[Lee]

The amount of Flow Tom was getting through his wastegate at the RR was unbelievable. Actually, it highlighted the need for a better EM design than most of the tubular ones I have seen. The reason for the pipe in the photo above on the Blue avant was that they estimated they would need at least a 4" downpipe to handle total engine exhaust gas flow at high revs. The separate pipe helps the situation here. Most turbocharged race cars have a separate pipe too.

[4WheelDrifter]

Somebody here tried to tell me that the wastegate just releases a bit of pressure in the EM.

[Lee]

Wasteagte flows all gasses that the ECU doesn't want to go through the turbo. The amount of gas flowing depends on the turbo selection and required turbo operating regime. With a monster turbo the WG will flow lots of gas if the top end boost is going to be kept low-ish.

[4WheelDrifter]

I'm looking at doing a EM with 5 separate runners to a more remote wastegate. It might be a bit overkill for a stock K24, but i've got enough stainless buddies around me. I though it might be fun to give it a go. T'is damn tight for space in the ol' S2!

[Lee]

Take the airbox out and there is loads of room.

[Lee]

Also, you probably want the wastegate as close to the turbo flange as possible. All gases, either going through the turbo or wastegate, needs a design to minimise kinetic energy loss.

[NoNonsense]

The amount of Flow Tom was getting through his wastegate at the RR was unbelievable. Actually, it highlighted the need for a better EM design than most of the tubular ones I have seen. The reason for the pipe in the photo above on the Blue avant was that they estimated they would need at least a 4" downpipe to handle total engine exhaust gas flow at high revs. The separate pipe helps the situation here. Most turbocharged race cars have a separate pipe too.

In some thread, Minhea recommended a 3.5" turbo-back...wouldn't that be enough? Or is a 3.0" and a separate wastegate pipe better?

[Lee]

You can fit a 3.5" turbo back on a URS4 but on an S2 the subframe location means that it is easier to fit a 3" plus a 1.5" to 2" WG pipe.

[4WheelDrifter]

Also, you probably want the wastegate as close to the turbo flange as possible. All gases, either going through the turbo or wastegate, needs a design to minimise kinetic energy loss.

It's back to the old question of do you lag the EM or not.
I not sure it would be a pretty looking thing. I was thinking of taking the wastegate headers from near the head, and making them a similar length to the ones that go to the turbo flange. A sort of Y on each of the exhaust ports. I'm not sure how easy it would be to create equal length, free flowing design on all ten pipes.
I haven't got hold of any CAD software yet. I'm more into model making at the moment.