Dump Valve location
Turbo Mini Forums

Well i have tried searching but couldnt find anything so thought i would ask.

From searching it seems everyone modifies the plenum to fit their dump valves, but is there an advantage of doing this over fitting the dump valve in the intercooler pipework?

As for me personally it would be easier to fit the DV into the pipe work for the intercooler.

The closer to the Plenum the better! I believe its to relive the excess boost from the butterfly as soon as possible?

Before the intercooler is better.

Me too.

the reason people say close to the butterfly is to minimise airflow reversal but the downside of it is that insignificant it doesnt really matter (as most of the time it gets dumped anyway) at really high boost it can cause problems though
almost all stock turbo cars dumpvalve is located close to the turbo before the intercooler

Yes i moved to the darkside

Instagram @jdm_brett

Surely 90% of TM setups have the dv after the intercooler though next to the butterfly?

I thought that too Gav. I remember someone tried using the dump on a cossie cooler and had problems. Can't remember who though now.

If something is worth doing, it's worth doing half of.

Mine is also going before the intercooler on the logic it's there to protect the compressor against stall.

And as per Brett, most OEM configurations are that way, BUT 99% of OEM is fuel injected so maybe there are other criteria that affect the decision with a carb ???

Other point, if you do put it before the intercooler it will see more heat so make sure the diaphragm or piston seals are up to it.

Schrödinger's cat - so which one am I ???

Mine on the cossie intercooler take off pipe.

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


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mine's in the bin

Isn't the initial back pressure generated at the butterfly as the throttle closes, so the ideal place to relieve the back pressure (have the dump valve) is as close to here as possible; on the plenum chamber?

Otherwise "the system" has to feed the back pressure from the butterfly through the pipework and intercooler and up to the DV located by the turbo? Losing all pressure "in the system" at the same time? And tbh, probably wouldn't act quick enough to do this between gear changes, it'd basically act as though there was no DV?

I might just be talking out of my arse though?!

Pottsy.

No, because it isn't the back pressure that operates a DV, a DV is operated by vacuum pulled in the inlet manifold after the throttle plate as soon as the throttle plate is closed (carb or injection) so to protect the compressor, the fastest way to lose pressure at the compressor is to have the DV there. As air is a compressible fluid and there will be lots of pressure drops around the system (especially the intercooler) the pressure will not be lost everywhere at the same time.

Unless, as I suggested earlier, there are different criteria for what needs protecting on a carb setup.

The original BOV (standard Metro plenum), not a DV, was the thing operated by back pressure.

Schrödinger's cat - so which one am I ???

Most of these theories are pretty sound in one way or another.

But in practise I don't think you'll notice any difference no matter where you put it.

Ah that makes some sense - hence the Ø6mm pipe that runs from the DV to the inlet, yes. Hmm, I'll have to have a re-think about that now!

Though "hopefully" as Tom says it won't make a huge difference where it is, and considering I have a "Hywel-special" plenum chamber now I don't think I'll be changing my setup any time soon!

Dave.

i have mine on my plenum! cheers nic

The standard dump valve on my scooby is on the outlet of the intercooler, which is just before the throttle.

Edited by metroturbo on 6th Dec, 2009.

On the Z20LET's the OEM valve is on the compressor of the turbo itself.
When ive fitted a aftermarket DV its been put close to the plenum, the only thing that made a difference was where i picked up the vac from.

IMO it shouldnt really matter where in the system you put it but i am leaning towards putting it before the cooler to dump hot air more quickly.
What i think does matter is where you pick up the vac from.

If one fits the DV after the intercooler, be at least as smart as to route the air into the hose between the filter and turbo inlet.

I'm all for the pre IC fitment, however, the air here is probably hotter than the ambient air, so the recycling DV might not be as clever.

I'm thinking DV after IC now, and a short hose to the turbo inlet pipe.

V I like your thinking. . . . . . .. . . .off to Ebay

"So wat we gonna do tonight Brain?"
"Same thing we do evernight Pinky!"
"Try to take over the world!"

on my 20vt A3, the standard dump valve is often upgraded to a piston type valve, which as standard is mounted before the IC. these tend to overheat, causing them to stick. it's also not great as it recircs hot air back into the system.

it's a really common mod to relocate the DV to the coldside between the IC and the throttle body.

This also stops it recirculating hot air back into the turbo inlet.

I've never seen a recirc setup on a mini though!

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.