dump valves
Turbo Mini Forums

put a dump valve on me plenum,put this blue one on my mate gave me,has a rubber piston thingy bob, it was loud and it went off at low revs when the boost is there,but i noticed when changing gear it slowed me down as the turbo took another second to spin up where as it was already there when it didnt have one, have put another one on it now and its like it was before but not as loud and only goes off in medium to high revs. so is this the better one? the piston seems alot harder to touch than the other,and alot harder to push down with your finger where as the other one didnt need much pressure on it.

so....is there dump valves that can loose you power and is this one,or is it one where the rubber bit reacts with the fuel and goes soft and shitty?


cheers

guessing the spring rate is different

ive just noticed the one ive put on now is a twin piston.... that mean anything??? is it suitable?

Think about it this way, the louder it is the more air you are venting to atmosphere. The more air you let out of your system the more time the turbo's compresser will need to re pressurise the air (so it will be laggy inbetween gear changes). This will get very noticeable once you have an intercooler and more pipework plumbed in!

The smaller dump valve will not be as loud as its not dumping or "wasting" as much pressurised air from the system.

Not forgetting with no dump valve the pressrised air can build up behind the closes butterly to the point where it stalls the turbo chargers compressor, this will also give a laggy effect as the stalled turbo has to sping up again.

I personally run a small diaphram dump valve, in theory it lets just enough air out to keep the turbo spinning, but not enough to be classed as "wasting air". It does mean that is not very loud, outside the car you cannot hear it above the gearbox...

ok i see what your saying,but the one ive put on it now is bigger than the other one (which was the normal size one like most people have on here) and is a duel piston one too,the spring seems to be harder to compress aswell.

hmmm, i realised i didnt answer you question at all.....

I belive piston dump valves have metal pistons sitting in a rubber seal. When the petrol contaminates the rubber it causes the piston to stick In the rubber seal - so it doesnt blow off quickly.

If you are pushing up and touching rubber i guess its a rubber diapram type u have.

But i have never had a piston type so i dont knwo....

surely the more boost pressure you have the louder it will be ???????

Metro turbo weekend driver,Mini turbo in the making again!