recirculating dump? or run without?
 

never looked into this but say on a boosted application you didn't want the poo valve going off and making that sound what would you use or do to keep it quiet?

also another thought if running low boost ie 8psi or so dv or no dv?

Most oe valves are recirculating. Still noisy at times though. You want to stop the noise completely?

wouldn't say completely craig but less obvious as to whats going on

Can you not buy closed loop valves off the shelf? That would be a better option than a dump valve. Would also hold boost higher and for longer :D

interesting it will be something I look into then

a recirc one puts the dumped boost back in to the inlet before the turbo

or either take off the DV or dont connect the vacumn line to it so it wont open when the throttle shuts

wont that cause turbo stall with no dump valve. i.e bad for turbo :s

only if your running lots of boost

I wouldnt recommend that martin, although it wont do any immediate damage, it will reduce the service life of the turbo considerably.

OEM's fit them for a reason. You can still hear them (my OEM ibiza was still noticable), but they are better than nothing

been thinking low boost application 8psi max dv or no dv?

no dv will mean slightly slower re-spool through the gears (probably unnoticeable on 8psi) and wastegate chatter which I personally like the sound of. Depending on the turbo, 8psi and no dump valve will probably do no harm whatsoever, depending on it's thrust bearing design.

Fitting a recirculating dv is probably your best option - you can keep it fairly quiet that way, and benefit from keeping spool times as low as possible (have the recirc outlet as close to the compressor housing as possible).

I've never seen a turbo fail (or heard of a turbo failing) as a direct consequence of having no dump valve fitted.

interesting Ross tbh with the spec in mind its going to be pretty much like steveo1600 diy setup using the stainless ebay mani t2 turbo etc etc just pricing everything up for local guy wanting to do it but he wants to keep it quiet. But still good to know it won't kill the turbo :) btw hows yours coming along now after the valve incident?

Yeah I dislike the dumpvalve sound now completely - when I had the R5 15-16 years ago, 30psi through a forge dumpvalve was all I lived for :p But tbh it's got really tiring and too chav for me. I recirc now and wish I didn't have to run one at all, but with such a large intercooler and high boost it's a necessary evil else the turbo would be stalled the whole time.

Car's doing well thanks - we've had a lot of grief with that bloody valve and the knock-on effects of it. Head's been off twice since then to try and rectify a problem with the valve seat we thought we had fixed. Bloody thing. Mapping is on Friday where we should see a reasonable gain in power as we're not binding the valve springs this time... :oops:

aye agree with your spec you will need one well over 350 now ain't it, Mauritius blue is such a nice colour on a gti. Ah good luck on the mapping hopefully see some nice figures and curves, anyway I think such low spec thats being talked about this will be sans dv

Thanks again for the compliments. It was at 403 last session. Should be somewhere around that (410-420) this time I hope. :)

excellent choice to go sans dv. :D

My engine still has the original turbo with standard built in recirculating valve. When I blocked the valve I noticed car became a bit more laggy

A recirc DV can increase intake temps, since your putting the same air through the turbo multiple times. Recirc DV's are needed if you are measuring the mass of air using either an AFM or MAF sensor. MAP and TPS and AIR TEMP doesn't need that.

You can get quiet DV's can't you?

No DV will make spool up slow and annoying :)

My dads old sierras cosworth never dumped, the car became uncontrollable on the road and shut the ignition off on the first touch of the throttle. That was years ago, but interesting story non the less :)

interesting will see how this pans out and report back with finidngs

just box the DV off to deaden the sound in an old open filter full of exhaust packing or cotton wool ;)

seen it done a few times, its quite effective!

..as well of course as being easy and cheap