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Dump valve

SK08BYT

By SK08BYT
in Scottish Scoobies

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scouk

scouk

Posted
Posted (edited)

99.9% of cases.. nope no remap required..

The problems occur when you either buy a cheap one or a vent to atmosphere (VTA) one which arent setup/configured properly and the valve remains open when at idle.. therefore spewing air out to the atmosphere rather than keeping the intake closed.. There are also the issues with the VTA where the engine doesn't get the air it's expecting, because it's been vented. This can cause irregular fuelling, causing more fuel to enter the engine than should normally go in which can cause other issues. But I've never heard on any reports of failure after an aftermarket dump valve was fitted correctly.

Thing is the car will always run better with a recirculating valve (one that doesn't go whoosh, psshhht, or wheeeeee!) Because the engine is running the way it's intended. Also lag between gear changes can be affected by fitting after market VTA valves because you are getting rid of already compressed air rather than re-using it, therefore having to start all over again..

Worth noting that the fuel issue can be accommodated with a decent quality remap..

What sort of dump valve were you thinking about?

Edited by ScoUK
johnmacdonald

johnmacdonald

Posted
Posted

99.9% of cases.. nope no remap required..

The problems occur when you either buy a cheap one or a vent to atmosphere (VTA) one which arent setup/configured properly and the valve remains open when at idle.. therefore spewing air out to the atmosphere rather than keeping the intake closed.. There are also the issues with the VTA where the engine doesn't get the air it's expecting, because it's been vented. This can cause irregular fuelling, causing more fuel to enter the engine than should normally go in which can cause other issues. But I've never heard on any reports of failure after an aftermarket dump valve was fitted correctly.

Thing is the car will always run better with a recirculating valve (one that doesn't go whoosh, psshhht, or wheeeeee!) Because the engine is running the way it's intended. Also lag between gear changes can be affected by fitting after market VTA valves because you are getting rid of already compressed air rather than re-using it, therefore having to start all over again..

Worth noting that the fuel issue can be accommodated with a decent quality remap..

What sort of dump valve were you thinking about?

scouk

scouk

Posted
Posted

Thanks for that. I think I will now replace my Forge Motorsport VTA with the original.

Have you been experiencing running problems since fitting it?

Should point out I run a VTA valve (well hybrid, it 's variable between vta and recirc) on my impreza have have done for a couple years now always been fine. It's just worth understanding what affect a VTA valve has on the car. As I mentioned above to the best of my knowledge there has NEVER been any reports of mechincal failure as a result of having a VTA valve fitted.. and fitting one does not require a remap!

The common fault comes from those where you can set the spring pre-load or have different options of springs and dont have the correct one fitted. When the car is idleing the valve should be fully closed.. If it's not you'll have problems.. Some people buy complex ones which need setting up and just try plug n play.. Or buy 2nd hand ones with a soft/worn spring which isn't suitable..

johnmacdonald

johnmacdonald

Posted
Posted

Not aware of any problems, apart from replacing spring last year, but currently it seems to be "blowing off" at lower boost than expected and now probably needs a complete maintenance kit. Our WRX runs at about 270 BHP. How do I know if the valve is fully closed on idle?

I'm a bit panicy at present, having just spent £1,000 on replacing burnt out secondary air pump, its relay and also air valve. Could an inefficient or faulty Forge valve have any effect on the air system? Car has only covered 32,000 miles and has always been serviced properly.

Thanks for uour other opinions on this subject.

John MacDonald

scouk

scouk

Posted
Posted (edited)

Hi John,

Our WRX runs at about 270 BHP. How do I know if the valve is fully closed on idle?

The engine will sort of cough and splutter. mostly.. Not sure about the forge valve but on those where you can see the trumpet/output you can see the piston inside and visutally check that the piston is closing off.. But if the car is idleing fine then there's no issue there :icon_salut:

Triggering at low boost can be normal.. THe valvue effectively triggers when you lift off throttle.. What happens is the air which normally flows throught the air intake finds a closed off door and ends up getting pressurised in a sealed container. Naturally it wants to find the easiest way out.. WHich is where the BOV comes in. So as long as the pressure is more than enough to push the valuve open you'll get the effect. If you are running the same boost levels as before and you are finding it venting off a lower boost levels, it may be an early indication that the spring is getting weak..

This video clip is sort of relevant as you can see how the valve opens up.. Not all valves are adjustable like this one and most are fixed setting (Note sound quality in this video is rubbish):

The dump valve is solely part of the air intake/turbo system and is unlikely to have been a cause of your other issues..

Edited by ScoUK
johnmacdonald

johnmacdonald

Posted
Posted

Thanks so much for the information. The WRX idles and drives fine and the Forge dump valve is not adjustable, other than by choosing differently rated springs. I will ask Forge for advice and then make a decision.

Happy Christmas!

John

SK08BYT

SK08BYT

Posted
  • Author
Posted

That’s my problem there are so many to choose from.. I like the idea of the whoosh fart burp but do not want to wreck my engine in the process....

99.9% of cases.. nope no remap required..

The problems occur when you either buy a cheap one or a vent to atmosphere (VTA) one which arent setup/configured properly and the valve remains open when at idle.. therefore spewing air out to the atmosphere rather than keeping the intake closed.. There are also the issues with the VTA where the engine doesn't get the air it's expecting, because it's been vented. This can cause irregular fuelling, causing more fuel to enter the engine than should normally go in which can cause other issues. But I've never heard on any reports of failure after an aftermarket dump valve was fitted correctly.

Thing is the car will always run better with a recirculating valve (one that doesn't go whoosh, psshhht, or wheeeeee!) Because the engine is running the way it's intended. Also lag between gear changes can be affected by fitting after market VTA valves because you are getting rid of already compressed air rather than re-using it, therefore having to start all over again..

Worth noting that the fuel issue can be accommodated with a decent quality remap..

What sort of dump valve were you thinking about?

scouk

scouk

Posted
Posted

Blow off valves are a pretty straight forward install, 5-10 mins max. Any trustworthy mechanic should be able to do it no problem.. Or ask someone local on here to fit it for you? The Forge valve doesn't have any spring adjustment on it like the one mentioned above so it's plug-n-play as it were.. :thumbup:

SK08BYT

SK08BYT

Posted
  • Author
Posted

Ill give it a bash i think... Thanks for all the posts guys much appreciated..

Grant. :UK-flag:

Blow off valves are a pretty straight forward install, 5-10 mins max. Any trustworthy mechanic should be able to do it no problem.. Or ask someone local on here to fit it for you? The Forge valve doesn't have any spring adjustment on it like the one mentioned above so it's plug-n-play as it were.. :thumbup:

spect

spect

Posted
Posted

only took me ten minutes, you may need to make a gasket or use some hylomar to seal it on your model, there was a rubber sealing ring on my MY06 intercooler but when I fitted a MY08 STi intercooler it was a smmoth fit, so I used some sealing compound after trying a hand made gasket (was not too happy with that attempt) works very well now.

johnmacdonald

johnmacdonald

Posted
Posted

Suggest you email via www.forgemotorsport,co.uk. They are incredibly helpful - may be able to supply direct. When you say adjustable, I know that Forge supply tuning kits that contain different rate springs and spacers...

SK08BYT

SK08BYT

Posted
  • Author
Posted

[ive had information from some guys at work that say they tried fitting dump valves but their cars didn't run properly after fitment but the fine people that have made posts on my post have told me why, because the valve has to be closed during idle hence i suppose you have to be able to adjust it somehow..

quote name=joshuajames' timestamp='1325697837' post='1435103]

Suggest you email via www.forgemotorsport,co.uk. They are incredibly helpful - may be able to supply direct. When you say adjustable, I know that Forge supply tuning kits that contain different rate springs and spacers...

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