An uprated dump valve will help if you are running high boost and your std one can't cope and starts to leak boost under full throttle. That is the only time it'll help. Other than that its just all sound and not really much else.

Andy

 

Sorry, but there's nothing like taking a huge dump after you've just spun her up to 6,000 rpm!!
Cant understand why they would be gay.

 

I have an SSQV and no its not on a Scoob. Unfortunately the standard re-circ item would not handle 1.35 bar at 8,500 rpm

May get the recirc kit as its too noisy IMHO.

 

They sound really cool. Don't you just love the scene from 2 Fast 2 Furious when he's at the lights revving his EVO 7....grrrrrrrrr...psssshhhht...grrrrrrrrr...pssssh hhht!

Also aid natural flames if on a decat

 

but what I want to know is why does my exhaust now pop and bank since swapping my DV???

 

Cheers Lee

I have one more question.

My BOV is adjustable the instructions say slacken the vacuum pipe screw until all the spring preassure is released then scre it in 1 whole turn. what would happen if I screwed it in a bit more would it make it open later or would it just **** up the whole system.

Do I need it easy to open or slightly harder.

Cheers

oh I have a GFB hybrid from http://www.gfb.com.au


[Edited by Wurzel - 11/12/2003 3:26:26 PM]

 

Wurzel,

It's a balancing act. Too easy to open and you will increase lag as all the boost in the intake will be lost, also more air will pass the MAF so your fueling may be further out.

Too stiff and you will be retaining too much boost in the intake and putting increased load on the turbo and shortening it's life. You will however reduce lag and fueling problems.

It really needs someone who knows what they are doing to set it up correctly.

Lee

 

Ok Mark , dynamic detail would be nice. I'm just a Nuclear engineer with a degree in electronic engineering, so its a little out of my field.

We have a few 11,000V 5MW blowers at work though, and as the discharge is closed, you can see the current drawn by the motor fall. Don't think this fact is often appreciated by people with turbo's

 

Any one here who's NOT an engineer!!

Gary: - I suppose its the same when the vacuum cleaner bag is full...the motor spins faster

 

Another engineer here.

In a semi uncomplecated explanation.
It's interesting that most people think it's the turbo that stalls with no DV when in fact its the air that stalls across the compressor blades. The load on the turbo actually decreases at this point and the turbo will keep spinning until it slows to a point where it is cutting air again or the throttle is opened and air is moving.

It's just the massive shock loading that is placed on any compressor at or just before that point that the air stalls that causes all the problems.

A couple of years ago we had a 4000hp ventillation fan put under that much load that the air stalled, this put the fan in the position where it was no longer able to cut the air across the blades and the load suddenly lifted (Stall). We ended up with the fan blades coming into contact with the housing causing a 4000hp, 10m diameter cathrine wheel complete with sparks and flames. Not what you want in a potentialy explosive atmosphere.

Lee

 

Gary, ta for that,

Im a rotating machinery engineer, so I understand the principles of centrifugal compressor shut in etc Trying to explain simply for the masses. I can go into detail if required

I have seen instances with centrif pumps, where a control valve has snapped shut very quicky, and caused a water hammer effect, sending a massive pressure wave back to the pump, and actually splitting pipework. Same principles for a compressor.

AliB, your question confused me, as you seemed to be confused why your performance dropped with a permanantly shut DV Obviously the DV helps performance, which is why its there. Thats why the question is a bit pointless.

If you're asking whether aftermarket atmos DV's improve performance over standard, thats a different question.

MB

[Edited by Dark Blue Mark - 11/12/2003 10:44:42 AM]

 

Wurzel.

Because the DV confuses the ECU as the air dumped has been measured by the MAF meter so the ECU fuels for that air dumped creating a rich mixture. The danger is the Lambda sensor could pick up that the mixture is too rich and lean it off.
That is the extreme theory anyway, it al depends on what atmo DV you have fitted.

Have a look at this DV thread.
http://www.scoobynet.co.uk/bbs/threa...hreadID=238313

Edited to add.
A dump valve is a protection device not a performance device. (See above thread)

Lee

[Edited by logiclee - 11/12/2003 3:03:07 PM]

 

Nah, I'm a chemist ( industrial, not high street!)


[Edited by vulnax999 - 11/13/2003 12:03:32 AM]