Dump Valve

[enigma]

Where oh where is the factory dump valve located??? I had a look yesterday and couldn't see anything that looked like it fit the description?????

My understanding is that it is a recirculating type, and as such should feed back in to the intake. I am assuming this is after the Intercooler? But couldn't find it.

Second thoughts, it would be better before the intercooler so it gets cooled after its trip round the turbo...........I'll have another look.

[zedy1]

if you look from underneath its located pn the nearside the pipe coming from the intercooler dave

[enigma]

Haha, found it, what a damn stupid place to put it! :D

Did I see you were fitting or had fit an aftermarket atmospheric dump valve? Any problems with idling? I was thinking of getting a hybrid one, any thoughts?

[pjjohnson]

I'm on my second after market dump valve - the first one got a bit clogged up after a couple of years and started to give problems on idle. When new it was fine.

[Spirit]

Been think about one too - first thoughts are HKS - anyone got a different opinion ?

[enigma]

I was looking at a GFB Hybrid:

GFB HYBRID DUMP VALVE (http://www.impossible-performance.cwc.net/abdracing.htm)

:confused:

[zedy1]

got the hks bov £70.00 :D brand new was for the gto so i bought a flexi pipe and fitted it no probs with idle

[pjjohnson]

If its sound you want, go for it, but I wouldn't fit one for any performance reason.

The HKS is expensive, you can't see it when its fitted. There are loads of cheaper ones out there.

[Spirit]

Does a dump valve still work the same with an auto car then as you are not taking foot of the accelerator ?

[enigma]

The excess boost pressure still needs to go somewhere!

[Spirit]

Thought it worked when you released your foot from the accelerator or have I got it wrong ? When will it release the pressure - when it reaches a certain amount, when it changes gear ? Sorry to be so dumb on the subject

[BraindG]

Most production turbocharged engines are fitted with a dump valve. This is to vent away excessive turbocharger boost pressure when the throttle is closed.
All Sierra Cosworth and the original large turbo Escort Cosworth models use the same dump valve. The turbocharger fitted to the latest Escort Cosworth has its own integral unit.
The dump valve is the black plastic saucepan shaped object that you will see connected between the intercooler and the air inlet hose to the turbocharger. You will also see a small hose leading from the top of the valve to the inlet plenim on the engine. Inside the valve is a rubber diaphragm and a steel spring, with a small insert to support the diaphragm where it seats against the dump valve body.
The dump valve has basically two operating conditions; throttle open, and throttle closed. When the throttle is open, the boost pressure coming into the valve from below the diaphragm is equalled by the pressure onto the top of the diaphragm that comes via the small hose from the engine plenim chamber. As the pressures are equal, the spring holds the diaphragm onto its seat, and prevents the pressure venting away. When the throttle is closed, the pressure coming into the top of the valve is significantly reduced, INSERT INTO post VALUES (often to a vacuum); and the pressure below the diaphram lifts it away from its seat, allowing the excess pressure to vent away. As the throttle is reopened, the pressures again equalise, the spring pushes the diaphragm onto its seat, and the boost pressure cannot vent away.

[BraindG]

mine is set pretty low.. i can hear it when im doing like 2500 revs.. theres bolt ontop to tighten it... thus increasing the amount of pressure required to open

[Brind]

Baily make cheap dump valves and unless you have an hear for the sound difference between the Baily and the HKS there basically isn't any difference apart from the price.

IMO I prefer the induction growl which sounds much more aggressive than a wee whistle sound, whapppish when on high boost.
You ceratinaly won't gain power or any other benefits since we already have a recirculating dump valve.

[BraindG]

vrrrrooooom. ptssshhhh....vrrrrooooom. ptssshhhh....vrrrrooooom. ptssshhhh....vrrrrooooom. ptssshhhh....vrrrrooooom. ptssshhhh....vrrrrooooom. ptssshhhh....vrrrrooooom. ptssshhhh....vrrrrooooom. ptssshhhh....vrrrrooooom. ptssshhhh....

[Simon]

have you upgraded to a nine speed box:D :Ponder:

[Brind]

Make way for the men in white coats carrying straight jackets! Barry had finally hit the edge.:INSERT INTO post VALUES (

[enigma]

:D

[BraindG]

Originally posted by Simon
have you upgraded to a nine speed box:D :Ponder:

so i got a bit excited.. :INSERT INTO post VALUES (


Originally posted by Brind
Make way for the men in white coats carrying straight jackets! Barry had finally hit the edge.

Again?! i only just got back :INSERT INTO post VALUES (

[Spirit]

Go Barry mate ! HKS for me then - snob factor you see, sorry !

[Spirit]

Technical info on the HKS SQV :

http://www.tdi-plc.com/Technical%20SQV.html

[Brind]

One thing comes to mind when reading that info....
'SQV 'Quiet insert £13.95' erm...?? isn't the point to let it make a noise?

[Spirit]

Guess it's how much noise thats all mate - who cares, scare the old people ****less I say ......lol, only kidding !

[Brind]

LOL! :D

[pjjohnson]

In my experience with an auto the dump valve does not whoosh when you change gear, but it does when you back off suddenly after you've been on boost.

[Spirit]

Same for all I guess, only makes a noise when you release accelerator ?

[BraindG]

everytime i change gear it gooes PTSSHH!!.. when i back of slightly it goes PTSSHH .. but uf i suddenly back off it goes PTSSHH!! again.,. its like magic..

[Andre]

i used my recirculating dump valve , i jus dissconnected the pipe which comes from the dump valve back into the intake and clogged it with a INSERT INTO post VALUES (pvc stop) and used a hose clamp to keep the pvc stop in place, then i got a flex hose and connected it to the dump vale and ran it cross behind the fog light . after doing this it was dumping loader than my friends HKS dump valve on his evolution. Seriously this works and it dumps when the accelerator is shut at 3000 rpms or higher

[enigma]

Fitted my dump valve on Tuesday night at 9:45 INSERT INTO post VALUES (my wife didn't talk to me for a while!) in preparation for a trip up to Blackpool with work.

I got the Go Faster Bits INSERT INTO post VALUES (GFB) Hybrid one in the end as I was concerned about reports of non recirculating ones playing havoc with the AFM readings. Anyway I have been pi$$ing myself laughing ever since! It is just so cool!

The posts about it not dumping during gearchanges in an auto are correct, I have to say much to my suprise, but thinking about it it makes sense I guess. As the throttle butterfly is not closing during an auto gearchange there is no pressure differential between the compressor side of the turbo and the inlet manifold.........hence the dump valve stays shut. I am sure if I thought about it enough I could work a way round it, but for now just revving the nuts off it, bouncing it off the limiter with pops and burbles then coming off the gas is enough to bring an idiot grin to anyones face! :D

[enigma]

Install huge idiot grin on face :D

Then play the file.............

Whoooooooooooooosh (http://homepage.ntlworld.com/john.hidle/images/Dump Whoosh.wmv)

How cool! :cool1:

[BraindG]

im not sure if its the video or what.. but compared to the HKS one. its really quiet... my one can deafen someone :Eek1:

cant wait to see your car though! youve done so much to it in such a short space of time aswell.. most impressive :D

[enigma]

It was only in Neutral so I expect it was only dumping about 0.3 bar............its still fookin loud!