Does a dump valve actually lower the performance when fitted to a standard Z20LET engine ? Although I like the whooshing sound I swear the turbo don't kick in as much now ? anything you can get to rectify it ?
What your probably noticing is increased lag. Most aftermarket dump valves are placed between the intake and intercooler so that they are on show. The best place for them (in terms of lag) is between the turbo and intercooler.
Originally posted by tay Does a dump valve actually lower the performance when fitted to a standard Z20LET engine ? Although I like the whooshing sound I swear the turbo don't kick in as much now ? anything you can get to rectify it ?
Should of asked this before............
Do you mean it takes longer for the engine to start pulling hard after gearchanges or the engine does not pull as hard in any gear?
When you fitted the new dump valve did you fit anything to disable the standard dump valve?
You need to make sure that you have the right dump valve - for a Z20LET you'll need a twin piston dump valve to prevent leaking boost and occasional stalling.
As for performance, dump valves don't really give you anything other than the noise... even recirculating dump valves aren't very good on performance (as they claim to be), they recirculate already hot air which is useless.
Just read your last post you NEED to remove the old dump valve! take it out and bung the hole with a aliminium bung that should have come with the fitting kit... if you don't have an aliminium bung then cut about an inch and a half off the top of a sweeping brush - that will do the job perfectly until you can get your-self an aliminium bung.
P.S. dont forget to jubilee clip the bung in place! (or a really tight tie-rap if you can't put your hands on a jubilee clip).
When you do this you should notice that your car runs smoother, pulls harder and your dump valve has a punchier, louder sound.