Good to know mate!Originally Posted by bevan
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Good to know mate!
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I have one of these and it's been fine up to ~1.2bar. It's been installed approx 6yrs and no problems
https://h-dev.co.uk/product/re-circ-...v=79cba1185463
Should have said in stock location.
That's what I have. I thought it was ok until I did a boost leak test and found it was leaking off at about 10psi!it's not in the stock location however. I need to change it back.
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Last edited by CrazySx; 19-02-2017 at 21:57.
I have a forge man, can grab a few pictures later if needed but you can get the gist from this;
So I drove the car to work today and it feels like the DV could be leaking but I am not sure.
The reason I am suspecting it is because when I did my boost leak testing of the intercooler system, I bunged the inlet manifold hose and bunged the hot pipe from the turbo, and bunged the breather looking pipe that come from the inlet side (can't remember what it's called)
I then proceeded to fill the system with air and at about 10psi the dump valve was release it. I couldn't get to a bar. I then had to bung the dump valve lol!
On the basis above. Am I right in saying the DV should hold a bar before dumping? Or do other factors such as vacuum (to DV) determine this?
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It should hold a bar before dumping yes. (Depending on what spring it has in it) you don't really wanna put more than 10psi through your intercooler during a leak test though, it's not really designed to hold massive positive pressure!
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Really? I beg to differ. At 10psi I couldn't hear the leak. At over a bar it sounded like there was a mouse in the bay with its balls in a trap
I actually pumped the system to 2 bar and made sure there were zero leaks by the end of it.
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Intercooler will see whatever boost pressure your running so will hold plenty of pressure like 50psi+
Oh and if you blocked the intercooler pipe so the inlet manifold wasn't seeing pressure that will be why your bov was leaking as it needs pressure on the reference line to it
So do i need positive pressure on the vac line in order to hold boost? Should the Spring not be able to hold a bar, and the vac/positive pressure balances it out after that?
The spring will hold very little pressure on its own it needs equal pressure both sides of it to hold it closed
Personally I do a boost leak test on the intake side of the turbo and just block the breather line off coming from the intake pipe just remember to remove the oil filler cap aswell
That way it shows nothing is leaking at all on the entire pressure side including vac lines and manifold gaskets and the pipes you just refitted
Seems I'm wrong, disregard what I said! I'm sure the boost leak test guide I read said not to go much over 10psi, I assumed this was right as obviously the engine is consuming the boosted air meaning the pipework/ic is only carrying it, not storing it?
Regarding the dv, I assumed a 22psi spring would hold 22psi regardless of vacume/boost on the other side?
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It probably means if the boost pressure is 10psi there is no point testing over 10psi
The spring has to be soft enough for the manifold vacuum to pull it up when off throttle with positive pressure on the other side of the valve but close when the positive pressure has gone
Not sure where the 22psi came from but if you had a 1psi spring in it it would still seal shut under boost as if you have 20psi of boost you have 20psi on the bottom of the piston and 20psi +1psi on the top so you can see you don't need a massive spring to deal under boost
The spring just needs to be strong enough to withstand the vacuum pressure which would probably be Negative 10-12 psi
The spring in mine was advertised as a 22psi (forge website) it doesn't seem to open soon enough so I still get pigeon noises at lower revs.
Based on what you're saying I can go for a lighter spring and still be okay!? Cars running around 16psi, the lighter spring is up to 14/15psi I think..
Thinking about it what you're saying makes sense..
Sorry for things going a bit off track 😂
I know there is some science around it, but doesn't the spring and diaphragm work the same as the actuator? 1 bar Spring holds 1 bar, vacuum pulls it after that?
Just block it off and see what happens with the boost.
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It boosts ok now. But the reason I want to change it is because it doesn't feel like it's boosting hard enough. And when I did the boost leak test it was leaking off early.
I want to learn more about the positive pressure in the vacuum line vs the positive pressure of boost.
Maybe I am just being paranoid because of what I witnessed when doing my boost leak test.
What I really want or need is for someone to tell me with confidence that they did a boost leak test and their DV held air upto a bar.
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The dv vac line is taken from after the butterfly so when your on throttle boost pressure goes down the vac line to equalise the pressure. Against the dv plus the spring pressure which is probably 8-9psi. When you pet off the butterfly closes and the engine created vacuum which pulls the dv open the release the pressure in the intercooler pipework etc.
My ssqv was fine when teated at horsham prior to mapping
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Do you mean it held a bar without having to be bunged?The dv vac line is taken from after the butterfly so when your on throttle boost pressure goes down the vac line to equalise the pressure. Against the dv plus the spring pressure which is probably 8-9psi. When you pet off the butterfly closes and the engine created vacuum which pulls the dv open the release the pressure in the intercooler pipework etc.
My ssqv was fine when teated at horsham prior to mapping
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