Dump valve YES or NO?????

[J3OOSST]

its when you have an external wastegate.

A wastegate is a device which opens a small hole up in the manifold to allow exhaust gases to bypass the turbo thus controlling the amount of energy it recieves and doing this you can control boost.

On Most cars where the wastegate opens and bypasses the exhaust gases around the turbo just rejoins the exhaust system after the turbo keeping this process quiet.

A screamer pipe is when the gases are just vented to the air instead of back into the exhaust. When this opens its like having a 40mm hole in the manifold at full throttle. The car raws or screams as when compaired to back to exhaust systems which are quiet.

This is why when its vented to atmosphere its called a screamer pipe

Tim
xxxx

But is this a good thing or a bad thing ? does it inhibit performance in any way ? or does it just add noise for effect I presume ?

[TBDevelopments]

doesn't hamper performance in anyway.

Depending on the exhaust system it can actually be a benifit. If the exhaust system is a restriction then this will help as its venting alot of the air before it even gets into the exhaust reducing the amount of air the exhaust needs to flow.

If there is a good exhaust system then its mainly a noise of the process.

Tim
xxxx

[J3OOSST]

doesn't hamper performance in anyway.

Depending on the exhaust system it can actually be a benifit. If the exhaust system is a restriction then this will help as its venting alot of the air before it even gets into the exhaust reducing the amount of air the exhaust needs to flow.

If there is a good exhaust system then its mainly a noise of the process.

Tim
xxxx

mmmmm... a horrid screaming noise i gather from the name screamer pipe.. which makes me wonder why it would be wanted or am I wrong in my thoughts..

[george]

To fit an external wastegate I need a turbo which can support this. I can't do this with my CT20b can I?

[TBDevelopments]

not really no.

Or not with serious modification.

The benifit of an external wastegate comes from improved boost control, and its just easier to vent it to atmosphere afterwards.

The ct20b doesn't really have a boost control problem so this modification would be pointless.

Tim
xxxx

[george]

I just bought an AVCR from you so I am concider my boost problems sorted...
But soundwise......

[TBDevelopments]

well what i ment by boost control problem as in the standard wastegate can't flow enough to control the boost which is being produced. This is often the case with hybrid turbo's where the flow of the turbo has been increased but the controls (wastegate) are standard and can't keep up.

Tim
xxxx

[skinthespin]

And remember if you ever take your car on a track the chances are you will not pass the noise tests with a screamer pipe, certainly not on a proper track anyway, may get away with it at an airfield.

[TBDevelopments]

ah i rarely do track days so not that bothered.

How do they go about that on a trackday? as the screamer pipe won't come in until on full boost?

Tim
TB Develoments

[skinthespin]

Depends, somewhere like Elvington just do a static test and measure at 2/3 rds revs (105db), somewhere like Donny have meters all round the track so can't really cheat them.

[TBDevelopments]

ah, wandered how they did that. I knew about the static test but not the ones around the track.

Oh well not hard to route it back into the downpipe. I'll have that on offer for the kits i'm doing.

Tim
xxxx

[2barGee]

Thanks for absolutely no one answering my question after 3 pages.

ALl commnets are appreciated but to be fair . . . .

[skinthespin]

Thats funny cos I remember answering your question........or at least giving you my opinion, ill make sure I put some thought into your next post........

[TBDevelopments]

for now until proven 100% differently. Run a BOV.

Tim
xxxx

[SteveW]

Agree with you Gee Man, it did get a bit off topic

I also forgot to say that the Rev 1 and Rev 2 GT4's, including the Carlos Sainz/RC do not have dump valves at all as standard.

Only the Rev 3 came with a dump valve, that rubbish plastic thing with the rubber diaphram.

My car runs much much better without a dump valve. Lots of Evo owners don't use dump valves either because they run better. In my opinion try it without and see what ya thinks. It won't cause instant damage, turbo might not last as long but mine is still alive after 120,000Km without a DV.

HTH