how do you achieve that sound synonamous with rally cars, is it an attatchment, or by bypassing the dumpvalve.

 

Get rid of the d/v and blank it off.

 

same as last post get rid of the dump valve,the noise you want is the turbo stalling due to build up of pressure in system when throttle valve has closed.
have read on here somewhere it is not wise to run with no dv if you have a vf series turbo as they are prone to fecking up not sure if that is correct but worth checking out first

 

Induction kit and no dump valve....just be careful what turbo you've got as some are fine without a D/v and others are'nt

 

combination of a front mount and DV will do it, min does it niceley although only at lower boost, higher boost it fully dumps

 

same here, big turbo, fmic, induction and dump valve not dumpoing till 0.5 bar.

 

Don't think it is necessary to remove the DV.
You will definitely hear it more if you take away the airbox resonator (or fit an induction kit). I can hear mine since fitting a high flow panel filter.

 

The very hard chatter is compressor surge and is bad for the turbo's longevity whatever the brand, it can be caused by blanking off the DV, or running at high boost low flow (above the surge line on the compressor map) and can be compunded by using an intake pipe with poor flow 'quality' into the compressor.

The softer noise most people are speaking of here is an aftermarket DV dumping excess boost when lifting off.

Simon

 

is it safe to blank off dump valve on standard intercooler with a tdo4 turbo
any other possible damage running without a dump valve??

 

I don't think anyone will tell you it is 'safe', but I had mine blanked off on a td04 for about 4 months with no problems.

Some might say the worse thing that could happen is the compressed air that travels back through the turbo and out of the air intake could give the Maf a false reading leading to permanent engine damage

Possible but unlikely.

 

I'm running an Andy Forrest TD05 20g with no dump valve and Andy assures me this turbo is fine without a D/V.

The TD series turbos are supposed to be more than strong enough to handle running without a D/V but the VF series turbos are not.

Ask Jolly Green Monster,he's run no D/V on a TD05 for something like 80k miles with no problems

 

i am under the impression td series turbo's can take running with no dv but the vf's are not apparently the compressor wheel can fail

 

is it still running the recirc valve though?

as rookie says low levels of boost is what i think alot of us are on about

 

I'm running with no D/V or recirc valve.

 

so how does the boost disapate rather than backwash and stall the turbo? doesn't it create more lag?

(this is a question to understand it by the way not a sarkey one lol)

 

right then project tomoro at work make a blanking piece for my intercooler and get that tdo4 chattering

 

It does'nt, thats what makes the noise! The turbo itself does'nt stall, it's the air passing back through it.

 

But reverse flow through the turbo can't help but slow it down....

Dunx

 

Correct Dunx.

 

This may sound really stupid..... but doesn't the rally version Impreza have a DV?

 

Well i'm running 1.55 bar with no D/V and I can't tell much difference over how it drove with a D/V-apart from the noise obviously.

Drives really well

 

Totally different set up, the rally car is never off boost, even when the throttle is off. when the throttle is off the ignition retards, so the engine is in a "no power" state. Hence why you here the pops and bangs.

This allows instant response when the throttle is floored (no lag).

 

no, they are not allowed to run with dump valves. dont ask why as dont know!!!

steve

 

and get rebuilt after 500 miles ish

 

That is the obvious answer, however it's not so simple I fear. Yes in theory it will slow the turbine, however it keeps the system under pressure. So power should come in much quicker.

Think of it in terms of pumping water through a pipe. Lets make it a perfectly straight piece of pipe with pump exactly half way along for arguments sake and a pressure release valve (DV). Turn the pump on and let it pressurise the pipe to xx bar of pressure. Now lets say we need to cut power to the pump (turbo) for whatever reason (changing gear for example). Our theoretical dump valve dumps out the excess water to relieve the pressure. Then we re-engage the pump to get back to pumping water. Before we can get to pumping water at xx bar the system needs to re-pressurize so wasting prescious milli-seconds.

Now imagine the system with no pressure release valve whatsoever. We engage the pump and build pressure to xx bar. We disengage the pump again (change gear) and then re-engage to carry on pumping water. However, we have not released and wasted ANY of the pressure we had built up. It is still there in the system. So as soon as we re-engage we are up to full pumping pressure almost instantaneously.

Food for thought

 

Lovely drescription, but not really true.

Once the TB is closed the chattering noise you hear is the positive boost pressure you have built up leaking out of the system via the turbo. Once the chattering has stopped the pressure in the pipe has all gone and you are back to more or less atmospheric pressure.

 

well i made me blanking plate today at work....thanks boss and now ive got the velociraptor noise that i always wanted only driven a spirited 10miles but did sound good







not sure what he thought?? :

 

Cheers mate

I was rushing to type that up and completely forgot about allowing for the escaping pressure backwards through the turbo. I still can't help but think that pressure would be held better inside an unventing system though.

Hmmm, further thought needed I might send this to Mythbusters....


Oh, and here's a bit of turbo-chatter pants-splatter fun for any fans \/ Assuming you's all haven't seen it before that is.

YouTube - Pros drifting high powered cars in Mobara circuit

 

What a load of bollox frankly...

The chattering noise is compressor surge, its basically the same as stalling an aircraft wing, when the pressure ratio across the compressor is high (high boost) and the flow too low (so essentially low speed), the compressor blades stall, and the airflow seperates off the rear of each blade, then as the pressure ratio drops (as the compressor was very inefficient) the flow reattches itself and the pressure ratio goes up again, and the cycling continues...this is exacerbated by poor linearity of airflow into the compressor, no flow goes backwars or any other urban myth like that, read the notes on the modified scoobyet Spec C where they had compressor surge at high boost/low rpm after fitting an aftermarket turbo inlet...

Its not good for the turbo due to the shockloadings on wheels/shafts and bearings, although that doesn't mean it will fail...with my DV blocked I can't lift off rapidly at all without getting really bad surge.

WRC cars can run dump valves, but as they are managed to always be on boost, why would they want to?

Simon

 

hi i ran a wrx tdo5 ,1 bar of boost with a dump valve at first, took it off for the nice chatter sound and drove it about for 3 years no prob ,defonately no change in performance with no adverse affects.i personaly wouldnt worry about it to much