antno Posted March 21, 2013 Share Posted March 21, 2013 Hi I was just wondering if anyone knows how the standard twin turbo set up creates 17.4psi (1.2 bar) when the system only boosts to .8 of a bar? I have been having a problem with overboosting but to be honest I haven't spent too much time trying to fix it. The car has been off the road. The last thing I have to change is the wastegate actuator. Any help would be much appreciated. Cheers antno Quote Link to comment Share on other sites More sharing options...
Benjy Posted March 21, 2013 Share Posted March 21, 2013 Have you got both cats in place? Quote Link to comment Share on other sites More sharing options...
Nic Posted March 21, 2013 Share Posted March 21, 2013 Click -> BPU for a full explanation. Basically the stock catalytic convertors on a J-Spec TT restrict the flow of the exhaust gasses and the stock boost pressure to around 0.8bar. Remove this restriction by taking the cats off and the car will boost to 1.5+bar as the small wastegate is overwhelmed and can no longer regulate the boost pressure, this is why a restrictor ring is used to add back a certain amount of restriction into the exhaust to regulate the boost pressure to a safe level. Quote Link to comment Share on other sites More sharing options...
antno Posted March 21, 2013 Author Share Posted March 21, 2013 Ye I have a restrictor ring in place. A 1 bar whifbitz one. I think the problem is a sticky wastegate as I have run a pressure feed direct to the actuator and blocked off the vsv. So in affect it should open the wastegate as soon at it hits the 17.4 psi not when the ecu closes the vsv. I was just wondering how the 17.4 psi is created to operate the wastegate actuator if the system only produces .8 of a bar.That is for example on a car as it left the factory completely standard. Cheers. Quote Link to comment Share on other sites More sharing options...
antno Posted March 23, 2013 Author Share Posted March 23, 2013 Unless 17.4 is a typing error? Quote Link to comment Share on other sites More sharing options...
antno Posted March 26, 2013 Author Share Posted March 26, 2013 The workshop manual says that aswell Anyone with any ideas Quote Link to comment Share on other sites More sharing options...
Poshmalc Posted May 7, 2014 Share Posted May 7, 2014 Standard actuator opens at just over 10psi, not 17 Quote Link to comment Share on other sites More sharing options...
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