Dump Valve and M12 GTO 3

[AverageMPH]

Does a dump valve have any real benefit on M12 GTO 3?

[BobE]

I`m not sure they really do a lot, although the theory is they reduce the axial loading on the turbo impellors when you snap the throttle shut. I guess they also limit the chance of a turbo hose coming off due to high pressure in the pipework. But they sure make a good sound - especially when you change up whilst overtaking someone.....

[slipstream 1985]

how much are they?

[andygtt]

on the std turbos I think they wont make any difference... although some swear they feel faster after they are fitted so I guess thats as good excuse as any to fit one.

Id say fit it if you love the noise, avoid if you dont

[slipstream 1985]

its all about the noise! roughly how much are they?

[The devil]

http://www.forgemotorsport.co.uk/content.asp?inc=p...

have a look

[SimonJW]

I thought there was a bit more to it than that - something about quicker gear changes?

[BobE]

SimonJW said:

I thought there was a bit more to it than that - something about quicker gear changes?

Again in theory - the turbo impellors should keep spinning at a higher speed so you get more power/boost when you open the throttle again, but I can`t believe it`s significant. It aint going to speed up a gear change - that`s down to the selector mechanism that Lee thought acceptable and many don`t....

[alastairb]

vroooooom-ptssssssch !

[andygtt]

BobE said:

Again in theory - the turbo impellors should keep spinning at a higher speed so you get more power/boost when you open the throttle again, but I can`t believe it`s significant. It aint going to speed up a gear change - that`s down to the selector mechanism that Lee thought acceptable and many don`t....

There is a trade off... you initially loose boost when the dump valve releases it... theory is that this is offset by the fact the turbo is kept spinning and thus builds the boost quicker.

reality on our cars we have very small turbos and don't run that much boost, so its very unlikelly that the pressure will slow the turbo significantly in the first place so adding a dump valve to keep it spinning wont do anything.

I personally dont like the noise and prefer just the wastegate chirping... but I've had to fit a dump valve on my car due to the size of the turbo and boost I may run.

Edited by andygtt on Tuesday 1st February 12:23

[mgbond]

I have to say on mine the air intake system over powers the noise from the BOV (Filters on the bulk head).

When I first fitted mine I found that the lag between gear changes reduced. But it may of been because I was told it would. lol

Bondy

[AverageMPH]

Guy’s thank you all for your advice and opinions, I can now make an educated decision.

I've decided not to fit the dump valve and go for a rigid pipe system instead.

Cheers

Mike

[Gadgeroonie]

(the hardpipe kit is a waste of money too)

[andygtt]

Gadgeroonie said:

(the hardpipe kit is a waste of money too)

unless your running big boost or you need to replace a run for some reason

[leeshell]

Or for aesthetic reasons

[The devil]

andygtt said:

unless your running big boost or you need to replace a run for some reason

Why is it a waste of money, looking at my pipe it was almost collapsing flat when you blip the throttle. Unless its just because it was getting old

[BobE]

The devil said:

andygtt said:

unless your running big boost or you need to replace a run for some reason

Why is it a waste of money, looking at my pipe it was almost collapsing flat when you blip the throttle. Unless its just because it was getting old

Must be old or someones fitted a wrong spec tube - I think you should only get about 0.5bar negative pressure in that section and that shouldn`t collapse the tube.

[andygtt]

The devil said:

andygtt said:

unless your running big boost or you need to replace a run for some reason

Why is it a waste of money, looking at my pipe it was almost collapsing flat when you blip the throttle. Unless its just because it was getting old

i wasnt suggesting it was a waste of money... its well worth it IMHO