Dump Pipe Noise

[GTSSS]

I have a S2 R33 GTSt with a T3/T4 turbo. It is an internaly gated turbo with a hole in the Turbine housing and the swing valve in the dump pipe.

I recently had the dump pipe opened up and "high flowed", but now I get loud noise coming from the dump pipe which sounds like an open exhaust. the Dump was sealed with a gaskety and I'm pretty sure there are no leaks in it.

The noise does not sound like hissing from a leak, more like a large hole in the dump??

I also installed a Catco metal cat?

Has any one else had a problem with increased noise after installing a larger dump pipe, or if you have any ideas on how to get rid of this noise as it is quite loud when under load at low-mid revs.

Cheers

[R31Nismoid]

What you mean by having the dump pipe "hi-flowed"

I've never heard of such a thing. You can purchase a larger dump, but you mean literally milling the inside of the stock dump?

[Mr. Oizo]

What you mean by having the dump pipe "hi-flowed"

It means exactly that Ash, having the existing dump pipe ported out so it flows higher.

[satanic]

Why would you do such a thing? Aftermarket pipes don't cost THAT much... my guess is that it's now broken because of this "hi-flowing" business

[2BNVS]

its probably been machined too thin, just get a reasonable split dump pipe

ben...

[Munna1]

Never heard of that been done before. 2BNVS is probably correct id recon. My car was actually queiter at idol after I installed a 3"cat and dump.

[GTSSS]

The waste gate swing valve for the internal waste gate is built into the turbo flange part of the dump pipe (similar to a VL turbo) and i have not found any aftermarket units that have this feature. Thus I had Liverpool exhaust "high flow" it by cutting off the plate that usually covers the swing valve section and moulding a 3 inch pipe around it to suite.

I have a wrapped the pipe with Thermotec all the way to the cat, so if the steel was too thin I guess this would somewhat compensate?

It seems like this is not a common problem So I will have to do a more thorough investigation...

As an demonstration

The dump pipe used to look like this with a 3" pipe welded onto the rear:

And now looks more like this

Cheers