speddynille Posted December 25, 2006 Share Posted December 25, 2006 Im wondering somethings about the j-spec downpipe! Many people who say different things. Do you have to have one cat left or a restrictor plate? If you have a boost controller wont that solve the problem so it wont boost over 1,2 bar? I have just installed a hks evc5 bc in my car, and are going to buy a downpipe but need to sort this out first. Quote Link to comment Share on other sites More sharing options...
Jake Posted December 25, 2006 Share Posted December 25, 2006 Boost controllers can only increase boost, they can't lower it. So if your decatted j-spec is over boosting a boost controller will not help. That's why folks use a restrictor plate Quote Link to comment Share on other sites More sharing options...
speddynille Posted December 25, 2006 Author Share Posted December 25, 2006 Boost controllers can only increase boost, they can't lower it. So if your decatted j-spec is over boosting a boost controller will not help. That's why folks use a restrictor plate ok, so thats why. How much do a j-spec downpipe with a restrictor plate cost? Quote Link to comment Share on other sites More sharing options...
Kranz Posted December 25, 2006 Share Posted December 25, 2006 What's the availability of bigger wastegates for the J Spec, say if the turbo is removed & machined to a bigger hole?? Anyone tried this? I'm guessing that there's a limit on the diameter it can go to. Would the UK spec wastgate valve head fit onto the J spec actuator shaft?? Quote Link to comment Share on other sites More sharing options...
Kranz Posted December 25, 2006 Share Posted December 25, 2006 ok, so thats why. How much do a j-spec downpipe with a restrictor plate cost? Phone JPS as they make them at a low cost I believe. Phone number available by searching. Quote Link to comment Share on other sites More sharing options...
Nic Posted December 26, 2006 Share Posted December 26, 2006 I think some hybrid turbos are machined with a bigger wastegates. I have seen quite a few stock j-spec turbos with cracks on the casting on the edge of the wastegate. It seems to be a weak point on the casting, which would only get weaker if the wastegate was increased in size. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 26, 2006 Share Posted December 26, 2006 You can port the wastegate, marginally. I do this on J-Spec hybrids (which I don't like, but still...) It helps a bit, but there isn't enough material to make the opening substantially bigger in area. Quote Link to comment Share on other sites More sharing options...
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