924Board.org

u63af · Posted: Wed Feb 22, 2006 3:27 am Post subject: Dump valves work on 931s

just to let you guy know that i fitted a baileys DV26 twin piston dump valve today and it works perfectly. I blocked off the pop off valve where it goes to the inlet manifold and then sealed the hole on the inlet. The dump valve causes no adverse effects on my car and it appears to pull better along with making a good noise aswell now. There are no fueling problems as were expected.
cheers
Sandy

flosho · Posted: Wed Feb 22, 2006 3:50 am Post subject:

Any pictures of this setup? I'm curious because unless you have it plumbed in after the turbo and before the fuel dizzy, you would probably be puffing black smoke because the engine is still getting the gas that was metered for the air that is no longer going into the engine.

If I didnt confuse myself there, but yeah... any pics?

Oh and how did you block off the POV? With the turbo in the car or did you remove it?
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u63af · Posted: Wed Feb 22, 2006 4:37 am Post subject:

I plumbed it in about 6" after the compressor on the turbo. Dont think it matters where it would be as there are other cars that use the k-tronic system and they do not suffer any adverse affects when using an atmospheric valve.

I spoke to Baileys motorsport and they said i would have fueling probs with a single piston type but the twin piston valve is designed for cars with an air flow meter so it works well on the 931. Sorry but i dont have the lead for my camera at the moment but i will get pics for you asap. As for blocking the pop off valve, I blocked it off where the hose connects to the inlet manifold and then blocked the hole on the inlet aswell. It seemed the easiest way to do it.

Smoothie · Posted: Wed Feb 22, 2006 5:16 am Post subject:

"Cool" as they say.
Some more info (though they don't say how it works (other than "perfectly")) -
http://www.xfms.co.uk/viewprod.asp?prod_id=284
http://www.xfms.co.uk/prodspec.asp?prod_id=284

Let's see.... a vacuum connection + 2 pistons. Hmmmm....
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

bass gt · Posted: Wed Feb 22, 2006 10:56 am Post subject:

Sandy,

Great news!! Regarding the diabling of the POV, did you leave the piston in the turbo housing and just seal the inlet pipe to it? Hence relying on the spring pressure to keep the piston over the bypass tract??
Pics would be great when you get the chance. I'm thinking of doing the same to mine once the EFI goes in.
Regards,

Steve

bass gt · Posted: Wed Feb 22, 2006 10:56 am Post subject:

Sandy,

Great news!! Regarding the disabling of the POV, did you leave the piston in the turbo housing and just seal the pressure inlet pipe to it? Hence relying on the spring pressure to keep the piston positioned over the bypass tract??
Pics would be great when you get the chance. I'm thinking of doing the same to mine once the EFI goes in.
Regards,

Steve

u63af · Posted: Wed Feb 22, 2006 9:56 pm Post subject:

Yes steve, i did not go any where near the turbo just unattached it and blocked it off where it joins the inlet manifold. You may be better with the dv26-d as it has a slighlty stronger spring than the standard dv26. It has quite a long sound as opposed to the short blast that is normally heard. But i think the dv26-d will have a shorter duration of release.
cheers
Sandy

Smoothie · Posted: Thu Feb 23, 2006 4:10 am Post subject:

I have a thought on how the dual piston dump valve might work -
Think of the single piston version as a cylinder with inlet at bottom, piston held at bottom of the cyl by spring pressure applied from above...the piston is lifted when vacuum is applied at the upper end of the cyl, charge air is released to atmosphere through holes near the bottom of the cyl.
Then for the dual piston arrangement, start with a single piston valve, machine out the center of the existing piston to accept a smaller piston - an inverted cup shape with openings around its' upper outer periphery and held down by its' own smaller spring. Now when vacuum is applied to the upper end of the cylinder, the smaller valve lifts first, releasing charge air up through the vacuum port to the intake manifold - so that metered air goes to the engine rather than being released to atmosphere. -Then if/when the capacity of the smaller valve is exceeded by a larger burst of excess boost, the larger valve is pushed open and that air escapes to atmosphere through the outer openings the same as in a single piston dump valve. -So in some instances ("spirited" driving

), metered air would still be released, causing a brief enrichment of the air:fuel mix.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

flosho · Posted: Thu Feb 23, 2006 8:35 am Post subject:

$148!

Is there any other companies that make this type of BOV?

I'm awaiting patiently for pictures. Come Spring time I'll have the whistle and the WOOSH
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[This Space For Rent]

Khal · Posted: Thu Feb 23, 2006 3:11 pm Post subject:

flosho · Posted: Thu Feb 23, 2006 3:58 pm Post subject:

Benino · Posted: Tue Feb 28, 2006 3:59 pm Post subject:

why would the car pull better? Are you saying there is less lag? Blow Off valve shouldn’t increase power right?

Just wondering, does the stock pov not flow enough air to keep the turbo spinning and the pressure from building fast in the intake tube?
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1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA

u63af · Posted: Mon Mar 06, 2006 5:15 am Post subject:

Iyt just seems to pull better throught the gears. But i am maybe imagining it.