Which Dump Valve and where?

[jon200]

I am not 100% on pressure but it needs to be more than the pressure used normally surely.
They test with the inlet hoses still in place too


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[CrazySx]

Ok I think I found the issue the DV was plumbed in the wrong way round!!! It's been plumbed in like that for years! In fact it went to Horsham developments like that. 2a chip and rolling road at 286bhp and 300lb in April 2015.

I put it on the right way round and you would never guess what?? Lol

I am just thinking now.. I hope I haven't damaged it. It is a HDEV DV.

Pic of it plumbed in the right way round.


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[CrazySx]

I am not 100% on pressure but it needs to be more than the pressure used normally surely.
They test with the inlet hoses still in place too


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Yeah that's what they did on mine. But there was no leak then?? Weird.

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[CrazySx]

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

I just read through everything again and this makes the most sense!

The spring would only deal with the vacuum pressure as that's what opens the valve.

However what doesn't make sense is.. why does the vacuum change when you up the boost? I.e. why do they say the stock DV is too weak once you up the boost?

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 😂

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[autosri]

I thought there was a mod you could do to the stock one to block a bypass port and it would hold as much as an aftermarket one

[autosri]

Do a boost leak test again but leave the inlet manifold connected to the intercooler and pressurise the lot I'm 99 percent sure the DV will be sealed

Search YouTube for go fast Brett he is part of GFB

[autosri]

Do a boost leak test again but leave the inlet manifold connected to the intercooler and pressurise the lot I'm 99 percent sure the DV will be sealed

Search YouTube for go fast Brett he is part of GFB

[leno]

Funnily enough I have the same dv and that was also plumbed in backwards. Noticed when I pulled it apart to put a rebuild kit in it!

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[CrazySx]

Funnily enough I have the same dv and that was also plumbed in backwards. Noticed when I pulled it apart to put a rebuild kit in it!

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I drove the car to work today and my gosh what a difference!

When u rebuilt yours was there anything wrong with it?

Mine seems to be ok now.

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[CrazySx]

I thought there was a mod you could do to the stock one to block a bypass port and it would hold as much as an aftermarket one

There was and i did it too. There is a hole that you fill using a self tapper and then cut the head off. I thought i would buy something made for the job, as i didn't know how reliable that mod would be.

[CrazySx]

Do a boost leak test again but leave the inlet manifold connected to the intercooler and pressurise the lot I'm 99 percent sure the DV will be sealed

Search YouTube for go fast Brett he is part of GFB

I might do this, just as an R&D exercise more than anything. However, if your exhaust valves are open, don't u lose air?

[leno]

I drove the car to work today and my gosh what a difference!

When u rebuilt yours was there anything wrong with it?

Mine seems to be ok now.

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Nope nothing wrong with it, I bought it second hand with the pipework already attached hence plumbing it in backwards.

The rebuild was purely for piece of mind!

[autosri]

Stock cams don't really have that much overlap so it's not really an issue but you will loose some into the crank case which is why you need to remove the oil cap

[CrazySx]

Stock cams don't really have that much overlap so it's not really an issue but you will loose some into the crank case which is why you need to remove the oil cap

Cool, i am excited to try this, as the car has improved SO MUCH since i fixed the boost leak and the DV direction issue. If i discover any other leaks Manifold side, then i can't imagine how good it will be!!

[CrazySx]

This Video adds some perspective on what we should expect with the car running:

https://www.youtube.com/watch?v=KgGRfR6jt-c&t=26s

[CrazySx]

I know i may get flamed for this but its time to reveal what i bought:

http://www.ebay.co.uk/itm/1919421149...%3AMEBIDX%3AIT

Looks like a cheaper version of the GFB to me. The seller also seems reputable. I mean the HDEV DV is probably made in China anyway, we don't actually know what brand it is or who made it, just that we pay a lot for it so it must be good. Of course the fact that many have tried it and it works is a factor.

I will try the ebay link one out and let you know my findings

[leno]

Never know you may have found something decent on ebay! Report back how you get on

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[bevan]

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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You say you blocked it off at the inlet? Did you show both sides of the dump valve the same pressure as this is how they seal. They actually lift on relative negative pressure from when the throttle is closed.

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[bevan]

Have a look at this there is a whole playlist. Its from MCM and the info there is really good. https://youtu.be/vbQxqzdDdrs

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[CrazySx]

Ok so the Ebay dump valve arrived today. First impressions are that it looks like a very good quality piece of kit for what you are paying!

I will let the pictures do the talking.






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