Nic Posted January 19, 2006 Share Posted January 19, 2006 I was reading a post on the AU forum, one of the members was suggesting venting excess boost from the intake, as a means of limiting boost pressure, as an alternative to fitting a restrictor ring on a J-spec Supra. This is the article he refered to: http://autospeed.drive.com.au/cms/A_2778/article.html There were opposing views saying this would not stop the exhaust gasses flowing through the turbos, so they would still overspin and build up excess heat. Views please? Link to comment Share on other sites More sharing options...
Ian C Posted January 19, 2006 Share Posted January 19, 2006 I'd rather have a restrictor ring. The big problem with overboosting is 1) overspeeding the turbos and 2) overheating the intake charge. If you then bleed off a little bit of the resultant air charge, you still have overheated air and stressed turbos, so really it solves nothing. -Ian Link to comment Share on other sites More sharing options...
JohnA Posted January 19, 2006 Share Posted January 19, 2006 That's what the original 'dump valves' were doing in the early days of turbocharging. I wouldn't use this as the main boost control method though, rather as a 'failsafe' in case the wastegate locks shut. Link to comment Share on other sites More sharing options...
psymon Posted January 19, 2006 Share Posted January 19, 2006 A certain tuning company website states they do not remove the 1st cat, only the second one, as there is not much point cause you have to fit a restrictor ring. I can see there point in a way. Anyone want to enlighten me as to why full decat......... Link to comment Share on other sites More sharing options...
UltraFlynn Posted January 19, 2006 Share Posted January 19, 2006 This is the set up I have on my car. I have one Cat still in and a bleed valve to control the boost. Link to comment Share on other sites More sharing options...
Ian C Posted January 19, 2006 Share Posted January 19, 2006 I tested my hybrids with and without a restrictor ring. I videod an accurate digital speedo and used editing software to get the timings of when the speed reached 10mph divisions. I found that taking the restrictor ring out had no measurable effect on acceleration, apart from the boost going sky high. I also got no seat-of-the-pants difference. When CW sorted out a 1st cat removal pipe and a restrictor ring I damn well noticed a difference then The first cat is a lot more restrictive than a ring tuned for 1.2bar, and it's closer to the engine and so traps more heat - not so good if you are pushing the stock sequential setup. But then you'll pass the MOT with the first CAT in place -Ian Link to comment Share on other sites More sharing options...
Alex Posted January 19, 2006 Share Posted January 19, 2006 The only alternative the restrictor ring is the Apex'i adjustable exhaust valve...which is for noise but works well as a restrictor too. Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 19, 2006 Share Posted January 19, 2006 Venting boosted air would cause serious issues with the fuel map! Link to comment Share on other sites More sharing options...
Ian C Posted January 19, 2006 Share Posted January 19, 2006 Venting boosted air would cause serious issues with the fuel map! Not if you vented it before the MAP sensor On a MAF based car it'd be a disaster, yeah. Still a pants solution though. -Ian Link to comment Share on other sites More sharing options...
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