Dump Valve pressure setting

[ajb1967]

Guys,

I bought a dump valve from MotoConcept in germany since Justin had no stock at the moment .

It is factory supplied at a setting concurrent with 12PSI.It can be adjusted up to 30PSI.

If am running at full boost of 1.1 bar then what should i set the dump valve to re. the PSI so that it opens and closes at the right moment.

At them moment i am getting no discernible "swoosh" sound and have experienced a small loss of boost which i assume means that the valve is opening under full boost.

If anybody has expericnce on this then an answer is much appreciated since it will save me some time instead of me working on trial and error basis

rgds

Adrian

[Glyn Harper]

Normally you don't set dump valves. The have the main feed into them form the plenum pipe, then a smaller pipe that comes from the inlet manifold AFTER the throttle butteflys.

The second smaller pipe balances the pressure on the piston when the throttles are open.

When you close the throttles, you have a positive pressure on one side (all your boost) and the smaller pipe will be a negative pressure caused by the sudden vaccum created by closing the throttle bodies.

This difference in pressure pushes the piston against the spring and opens the valve as you effectively go from 0psi (balanced) on the piston to, in your case, about 35 psi when the throttles are closed.

I suppose it's a bit of trial and error to get your adjustable one right, but the way the ECU works on the Esprit it shouldn't really affect the car much apart from to make a different sound.

You probably get a shorter sharper sound if you have it set at 30psi.

Never used an adjustable one..

Logic would say you probably want to dump as much as possible, to get the most benefit from the valve.

Although there may be more to it than this?!

[ajb1967]

Hiya Glynn,

I tend to agree with you but since the factory set pressure of the valve is 12psi and i am running 16psi in boost my logic tells me i should have it set well above 16psi since otherwise the valve is going to be opening prematurely and losing my boost pressure even with the throttle open.In practice i testd this and it is correct since my boost dropped from 1.1bar to 0.9 bar when the valve was set at 12psi.

Hmmm,i will set it at 22 psi and see where that gets me :-)

thnx

Adrian

[Glyn Harper]

Does yours not have the smaller pipe to balance the boost?

It sounds more like an Indy car blow off valve than a dump valve the way you need to set it.

[mike_sekinger]

Does yours not have the smaller pipe to balance the boost?

It sounds more like an Indy car blow off valve than a dump valve the way you need to set it.

Although adjustable dump valves aren

Edited March 4, 2008 by mike_sekinger

[Glyn Harper]

Mike, you said exactly what I was thinking but couldn't put into words properly

[fjmuurling]

just for info 1 bar equals 14.7 psi

Freek

[ajb1967]

Bloody dump valve !

OK,this is an adjustable valve with a vacuum hose.

I have now set it up at about 20PSI which is 2PSI PSI over my max boost of 1.2Bar.So,theoretically it should be fine.

There again,i cant hear it blowing off when i change gear.Now,either my hearing is deteriorating ;-) (i doubt it ) or the noise of the exhaust (which is very noisy ! ) is hiding the sound of the valve.

So,the conundrum is,how can i check if it is working properly ? Ideas welcome :-) And ,no, i dont have Freescan ;-)

My Turbo does spool up very fast though but that is partly caused by the manual set up i have to control boost which holds the wastegate valve fully closed until max set boost is achieved.(yes ,i know it is agricultural as somebody pointed out to me so succintly a while ago hahahahaha)

rgds

Adrian

[mike_sekinger]

If the dump valve is a straight-forward