dump valve placement
Turbo Mini Forums

i was chatting about all things turbo with a friend of mine tonight, and he was saying how really i should put my dump valve before the intercooler likle the subarus have them, rather than after the cooler like almost everybody else. to start oif with i thought he was talking rubbish, but as usual he has a really good argument, and im seriously beggining to think he might be right....

turbo spins and presurizes the air which goes through the intercooler, and cools down. change gear, and all of the cycle starts again, but the air that was in the intercooled is now in the atmosphere, so we now need to cool down even more air.

now to look at it his way, the same thing will happen, but the air nearest to the engine will be colder, since the dumped air will come straight from the outlet of the turbo. seriously considering making up a dump valve take off from the interccoler piping rather than the plenum......

what do people think????

And on the 7th day........... God created turbochargers!

however...

air that is presurised on the engine side of the dump valve, will, when the valve is opened go to atmosphere too, to do this it wil have to change direction! then when the d/v closes it wil not only have to re-compress the air, it wil have to change its direction, and also the air wil need cooled again anyways as the intercooled air wil stil have made it to atmosphere:) .. my thought are that the d/v should always be close as possible to the throttle /plenum to keep the gas flowing the right way.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

interesting, and you may well be correct. what do other people think about this.....

And on the 7th day........... God created turbochargers!

I'd go close to the carb

I think you won't notice any difference at all...
Interesting argument tho!

how about having the closed loop system that dumps the air back into the air inlet system upstream of the intercooler, i know gttuning do these for the 5's because i nearly bought one when i had mine a few years ago

at least then the air wouldn't be as 'wasted' as dumping it into atmosphere?

called a recirculating dump valve, air has to be dumped to the inlet side of the turbo.

downside is no loud "ptschhhhhh" noise :(

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

just wondered if it benefits were greater than a normal dump valve, apart from the obvious lack of dump valve noises!!!

or is it a bit risky having boosted air dumped before the turbo, could it make it overspeed?

most productions turbo cars do this, so I can't see there being any problems

Team Racing

yeah thinking about it, it would probably be better for keeping the turbo spinning during the gear change

I fitted one of those recirculating dump valves from gt tuning on my 5 turbo a few years ago and the theory then was that the blast of air from the recirculating pipe would help maintain the turbo rpm speed during gear change and reduce lag.

did it work justin?

Dan,

The car certainly felt a lot different afterwards.the unit is designed so that the dump valve stays partially open at low revs so that the turbo has less resistance and can spin up higher than it normally would at low engine speed.This made the car feel as if the boost was a lot more controlled coming in and spinning the wheels when trying to pull away sharply from junctions was greatly reduced but without compromising on performance.

cheers justin, i was thinking wether or not i should be trying to accomodate a dump valve, and i think i will probably will