Scott Posted June 27, 2008 Share Posted June 27, 2008 Why do you always seem to assume the worst? I'd fit a RR if I were you. Well if its a UK turbo i thought they wouldn't overboost because of the larger wastegate? I was led to believe through this forum that the only way to raise boost on a UK model was to add a boost controller. If there isn't a boost controller on the car allowing the boost to be raised then there is something wrong? The most obvious thing i would have thought would be either the wastegate or something controlling it. Is the wastegate the "worst" thing that could be wrong? Surely if its a VSV slip then thats hardly anything? Quote Link to comment Share on other sites More sharing options...
Zofix Posted July 22, 2008 Author Share Posted July 22, 2008 OK my car is fuel cutting at 1 bar! If I don't want to install a fuel cut defender and a bosot controller, is it then possible to install a restrictor ring that will hold the boost just under fuel cut? Do people never install restrictor rings on UK/US supras?:S Quote Link to comment Share on other sites More sharing options...
Scott Posted July 22, 2008 Share Posted July 22, 2008 To be honest you shouldn't need a restrictor ring with a UK/US Spec supra. There must be some sort of boost controller on the car, either that or something is wrong with the wastegate system. Quote Link to comment Share on other sites More sharing options...
Zofix Posted July 22, 2008 Author Share Posted July 22, 2008 I don't think there is anything wrong with the car.. It do would it should hit fuel cut at 0.9-1bar, then people add a FCD and a boost controller to raise the boost. But I just want to know if it is possible to add a restrictor ring and hold the boost level a tiny bit under fuel cut level. Then I don't have to install a FCD and a boost controller. Will it harm anything on the UK/US engine if I add a restrictor ring? Quote Link to comment Share on other sites More sharing options...
Franko Posted July 22, 2008 Share Posted July 22, 2008 is it actually fuel cutting? Are you being thrown forward into the windscreen? Feel like you have hit a brick wall? Fuel Cut will do this and not make a "beep" sound from your gauge Were all these mods done at the same time as fitting a boost gauge or are they old mods? I dont see why fitting a boost gauge alone would make the car fuel cut Quote Link to comment Share on other sites More sharing options...
Zofix Posted July 22, 2008 Author Share Posted July 22, 2008 I removed both CATS + installed a HKS hard IC pipe kit + boost gauge, the weather is cold in Denmark not like the US, this will also increase the boost level a little bit, And yes it hits fuel cut when i floor it at 60mph+ boosting 1bar for 3 sec. Quote Link to comment Share on other sites More sharing options...
Scott Posted July 22, 2008 Share Posted July 22, 2008 I don't think there is anything wrong with the car.. It do would it should hit fuel cut at 0.9-1bar, then people add a FCD and a boost controller to raise the boost. But I just want to know if it is possible to add a restrictor ring and hold the boost level a tiny bit under fuel cut level. Then I don't have to install a FCD and a boost controller. Will it harm anything on the UK/US engine if I add a restrictor ring? Kind of going round in circles here. With a UK/US Spec the wastegate is big enough to cope with the tubby's spinning freely due to de-cat's etc (well so i have been led to believe on here). The ONLY way to get more than the stock boost is to add something to stop the wastegate from opening until a certain pressure so either the wastegate isn't operating properly or there is something mechanical/electronic holding it closed till you reach 1 bar. As said, fuel cut will come in at 1bar and feel like a brick wall. Quote Link to comment Share on other sites More sharing options...
Burna Posted July 22, 2008 Share Posted July 22, 2008 I don't think there is anything wrong with the car.. It do would it should hit fuel cut at 0.9-1bar, then people add a FCD and a boost controller to raise the boost. But I just want to know if it is possible to add a restrictor ring and hold the boost level a tiny bit under fuel cut level. Then I don't have to install a FCD and a boost controller. Will it harm anything on the UK/US engine if I add a restrictor ring? Don't worry, there's nothing wrong with your car. I know of two UK specs that regularly reach just over 1 bar after full decat and sports exhaust, mine included. Fit a FCD and enjoy You may want to buy a fields harness to preserve your loom Quote Link to comment Share on other sites More sharing options...
Zofix Posted July 22, 2008 Author Share Posted July 22, 2008 Kind of going round in circles here. With a UK/US Spec the wastegate is big enough to cope with the tubby's spinning freely due to de-cat's etc (well so i have been led to believe on here). The ONLY way to get more than the stock boost is to add something to stop the wastegate from opening until a certain pressure so either the wastegate isn't operating properly or there is something mechanical/electronic holding it closed till you reach 1 bar. As said, fuel cut will come in at 1bar and feel like a brick wall. Yes it is hitting fuel cut, and yes it feels like hitting something:blink: But then again, on UK/US spec every mod you make like(de-cat, FMIC and intake) Is adding boost. But I believe your right if you want to get boost level above 1 bar you sure need a boost controller, but in my situation I want it lowered abit so I wont hit fuel cut. Thats why I want to know if I can add a restictor ring, to hold it down. There were some topics on the US supraforum about people hitting fuel cut(with US-spec) at cold days and the only mod they had were de-cat. Quote Link to comment Share on other sites More sharing options...
Scott Posted July 22, 2008 Share Posted July 22, 2008 Don't worry, there's nothing wrong with your car. I know of two UK specs that regularly reach just over 1 bar after full decat and sports exhaust, mine included. Fit a FCD and enjoy You may want to buy a fields harness to preserve your loom Yes it is hitting fuel cut, and yes it feels like hitting something:blink: But then again, on UK/US spec every mod you make like(de-cat, FMIC and intake) Is adding boost. But I believe your right if you want to get boost level above 1 bar you sure need a boost controller, but in my situation I want it lowered abit so I wont hit fuel cut. Thats why I want to know if I can add a restictor ring, to hold it down. There were some topics on the US supraforum about people hitting fuel cut(with US-spec) at cold days and the only mod they had were de-cat. There's your answer. Guess its not quite so cut and dry as most people think afterall then Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted July 22, 2008 Share Posted July 22, 2008 If i where you i would just fit a FCD, there is nothing wrong with running your UK/US spec turbos at 1.2 bar, and yes if you have decatted etc, because the US spec turbos have an adequate sized wastegate, then you will see an increase in boost pressure and airflow. Quote Link to comment Share on other sites More sharing options...
Scott Posted July 22, 2008 Share Posted July 22, 2008 If i where you i would just fit a FCD, there is nothing wrong with running your UK/US spec turbos at 1.2 bar, and yes if you have decatted etc, because the US spec turbos have an adequate sized wastegate, then you will see an increase in boost pressure and airflow. Ok now i'm really confused. I thought the reason J-Specs see higher pressure is because the wastegate isn't big enough and the reason UK's stay the same is because it is? FAQ & Technical section needs updating if that statement is true lol. Quote Link to comment Share on other sites More sharing options...
Firestorm Posted July 22, 2008 Share Posted July 22, 2008 i had a similiar problem.. thought i didnt have double decat- found out recently i did.. but i dont have Iridium sparks - and i got a beep frm my defi guage and missfire.. mite wanna check your fuel pump too. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted July 22, 2008 Share Posted July 22, 2008 Ok now i'm really confused. I thought the reason J-Specs see higher pressure is because the wastegate isn't big enough and the reason UK's stay the same is because it is? FAQ & Technical section needs updating if that statement is true lol. Sorry that wasn't put very well, all turbos will see an increase in boost pressure/airflow if a restriction in the exhaust/ inlet is removed, (if there is one, most factory set ups do) other than that, its just the waste-gates that stop over-boost, and if they are too small like the J spec so hence the RR to replace some of that restriction, bit of a contradiction in terms really:) Quote Link to comment Share on other sites More sharing options...
Carl Posted July 22, 2008 Share Posted July 22, 2008 Defi gauges always read about 0.1 bar high anyway so worth considering. If the gauge showed 1bar ,you were probably doing 0.9bar in reality.. Carl Quote Link to comment Share on other sites More sharing options...
matt k Posted July 22, 2008 Share Posted July 22, 2008 I bought my MKIV completely standard and I am 99% sure that it never had a Fuel Cut defender or BCC installed. The only mod it has is a RMM downpipe and a HKS super Dragger Cat-back. Yesterday I installed a boost gauge. And when I floored it the gauge showed 1bar. And I thought shouldnt It fuel cut before 1bar!? Then I took it out on the highway, and I floored it again(unfortunately I didnt look at the boost gauge). The Defi boost gauge went "BEEP" and then I almost crapped my pants. I didnt see what the boost gauge was showing but I didnt like the sound from the Defi gauge. Can somebody help me, I don't want my turbos blown! I hope it is the boost gauge reading wrong.. Its a US-spec running 99 octan. If it's a US spec you shouldn't need a rr. Quote Link to comment Share on other sites More sharing options...
matt k Posted July 22, 2008 Share Posted July 22, 2008 Just read this has already been covered, as above i would just fit a fcd and a b oost controller and run at 1.2 bar (much more fun anyway). Quote Link to comment Share on other sites More sharing options...
Zofix Posted July 22, 2008 Author Share Posted July 22, 2008 I heard something about that it would harm the engine to fit a fcd, due to the engine is with MAF sensor, The fcd trick the ECU to think that it is runing lower boost, and will cause wrong fueling. Please correct me if I'm mistaking.. Quote Link to comment Share on other sites More sharing options...
Burna Posted July 22, 2008 Share Posted July 22, 2008 I heard something about that it would harm the engine to fit a fcd, due to the engine is with MAF sensor, The fcd trick the ECU to think that it is runing lower boost, and will cause wrong fueling. Please correct me if I'm mistaking.. First I've heard of that, it may be worth you posting that question in technical so the more knowledgeable members may be able to help you Quote Link to comment Share on other sites More sharing options...
Scott Posted July 22, 2008 Share Posted July 22, 2008 AFAIK it will go slightly lean top end but around the 1-1.2bar mark i think its generally accepted to be ok. Pretty sure the ECU is set to be rich at the top anyway. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted July 22, 2008 Share Posted July 22, 2008 A FCD will do exactly the same on an AFM equipped car as it will on the MAP equipped car, clamp the voltage just before fuel cut occurs, and as long as its not too low ie not for a Supra you should have no problems as the ECU runs over rich anyway. Quote Link to comment Share on other sites More sharing options...
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