I have a noise like someone blowing over the top of a bottle at about 3-4000rpm.I was told it was probably me dump valve,but now have been told it could be a waste gate prob,any ideas.Also if i change my dump valve what would you recommend and will i have probs with car running too rich which someone else has mentioned.

 

That noise is common and I believe it is the dumpvave.But if you are not happy with it and wanna change it,go for the best ones like Forge or Blitz.I didn't have one before and recently got "Le Mans" one fitted and didn't feel comfy with it at all.Superb sound but it was cutting revs and pulling back the performance of me scooby n loosing power at times.Today I got it out and original one fixed back on.I do miss the rich running and the dumping sound(it is buzzing!)but feel much more comfy with the standard fitting and will buy the best one next time!
Good luck with your dumping!

 

From the SIDC FAQ's

There seems to be a recognised problem with the 1997 specification car's dump valve. This does not shut properly under boost and thus vibrates giving the sound similar to someone blowing across the top of an open bottle. It has also been likened to a steam train whistle or ship fog horn in extreme circumstances!. Meanwhile the 1998 model seems to have a totally revamped and larger blow off system, but I have had reports that the problem sometimes still occurs.


Cheers
Lee

 

Thank you for your replys.I had already read that FAQ on SIDC,and was totally convinced until someone else said it could be the waste gate.I also emailed SIDC and they sent one back and said it probably was the waste gate.........so who do you trust.Turbohot are you saying you think if i go for the more exspensive valve i should not have probs or are you saying stick with genuine parts.
Cheers again gentlemen................
Baz

 

Yes,thats what I am saying! Cheap ones are waste of time.Good luck mate!