eyefi Posted November 19, 2001 Share Posted November 19, 2001 is it possible to turn down boost after a full decat (CW 2.5" pipes) on jspec with electronic boost controllers. if u cant why is this. is it because of stock wastegate not being large enough? if so can anything b done about this and how much would it cost? if u can what sort of pressure could u get it down to? stock levels maybe? i know it my sound strange to want to turn the boost down but ideally for me it would b useful because i would not want 16-18psi for running to the shops etc. basically it would b nice to choose full on nutter or pleasantly swift for whatever was at hand. Quote Link to comment Share on other sites More sharing options...
Graham Rudd Posted November 19, 2001 Share Posted November 19, 2001 Unfortunately the only way I could get my boost down after removing my cats was to stick the front one back in. The boost was shooting straight to 1.6bar without it... not a situation I could really live with. It becomes a real pain in the arse trying to keep one eye on the boost gauge when nailing it. Hmmm... probably a little dangerous too for that matter Graham Quote Link to comment Share on other sites More sharing options...
Brian Jackett Posted November 20, 2001 Share Posted November 20, 2001 I have got the CW down pipes and all you have to do is make up a metal gasket with a smaller whole through it to control the boost. Boost controllers cannot reduce boost, I am told. I will be getting some made up and can get some for you if you like, I am going to get a few made up so I can get the boost exactly to 1.275 regards Quote Link to comment Share on other sites More sharing options...
eyefi Posted November 20, 2001 Author Share Posted November 20, 2001 brian, ive heard of this fix b4 but it seem strange to me to open up yr downpipe by taking out cats and then putting something back in to restrict it again. is there any real improvement to the car if u put a reducing gasket in rather than leaving the 2nd cat in? the uk spec has some sort of boost limitation system built in. would it not be possible to fit this to jspec thus allowing u to turn boost down to 12-14psi. if u increase boost while the cats are still in is this more stressful for the engine because the gasses cant really escape fast enough or can u not increase boost beyond what gas can be expelled. ah! does this have something to do with flow rate, which is not the same as pressure? basically what i want to do is have a freeflowing exhaust (faster spool up / better sound etc) but still retaining full control of boost. why is it boost controllers cant turn boost down? Quote Link to comment Share on other sites More sharing options...
Brian Jackett Posted November 20, 2001 Share Posted November 20, 2001 It is a recommendation of CW to put in this restrictor. Remember you have not just de catted it you have put on a performance rear box opening up the exhaust system completely. Apparantly some boost ok some go to high, I am told that having 1.4 boost will not give any extra power then if you have 1.1 or 1.2 boost except that the engine will last longer. I do not know why boost controllers cannot decrease boost, someone else might be able to answer that. Putting a CAT back I am sure will restrict the boost and Power putting a restrictor in will just reduce boost with no loss of power. I might be wrong but I am NOT going to put a Cat back in I feel all naughty running no cats and thats how I like it Quote Link to comment Share on other sites More sharing options...
Gareth Davies Posted November 20, 2001 Share Posted November 20, 2001 Ok guys, you've got me confused. If a boost controller can't reduce boost, what the hell does it do?? I only have a typical blitz DSBC, and changing the values changes the peak boost, simple as that. My J-Spec has a de-cat and a hiper exhaust and with the boost controller set right it can be varied from 1.0 to 1.2 bar (well thats what I set it to, 1.2 is at 45%). God knows where it would boost to without it. Plus when you hit your limit it reduces the value by X percent to potentially reduce the spike. Quote Link to comment Share on other sites More sharing options...
GavinL Posted November 20, 2001 Share Posted November 20, 2001 Quote: from Brian Jackett on 1:54 pm on Nov. 20, 2001[br] I do not know why boost controllers cannot decrease boost, someone else might be able to answer that. I think that's because the wastegate operates at a set pressure. A boost controller of any sort will fool the wastegate into operating at a higher pressure than stock. Quote Link to comment Share on other sites More sharing options...
Alex Posted November 20, 2001 Share Posted November 20, 2001 Quote: from Gareth Davies on 3:13 pm on Nov. 20, 2001[br]Ok guys, you've got me confused. If a boost controller can't reduce boost, what the hell does it do?? I only have a typical blitz DSBC, and changing the values changes the peak boost, simple as that. My J-Spec has a de-cat and a hiper exhaust and with the boost controller set right it can be varied from 1.0 to 1.2 bar (well thats what I set it to, 1.2 is at 45%). God knows where it would boost to without it. Plus when you hit your limit it reduces the value by X percent to potentially reduce the spike. G, Are you sure its de-catted??? Have you had it up on a ramp?? If it is then you've got narrow de-cat pipes. Without the cats your car should not be able to run at less than 1.2bar!!! Hmmm....do you want to get it up on aaron's ramp when your next in town to double check. For you to hit only 1 bar sounds to me like you still have the 1st cat and probably a HKS Front Pipe to go with your Hiper Titanium Exhaust. The DSBC can't really limit boost but can sometimes be used to slow the build up and therefore slightly limit your peak boost. Quote Link to comment Share on other sites More sharing options...
Adam W Posted November 20, 2001 Share Posted November 20, 2001 Isn't the Titanium a full system from the turbo back? Quote Link to comment Share on other sites More sharing options...
Branners Posted November 20, 2001 Share Posted November 20, 2001 I was waiting to see if anybody else had managed to hold their boost down before commenting. It is possible, everbody says it just cant be done and that the wastegate just cant flow enough gas due to its size, but there are at least 4 cars that have been set up by Leon with a DSBC, no cats and a performance exhaust and they can hold it down to 1.0 or 1.1 I dont know how or why it does it and I have never asked Leon to show me as I wouldnt want to try and explain it to anybody, but generally if you have a DSBC then Leon can probably get it to hold the boost down a bit. The only reason I havent got a DSBC fitted is that Im sure my insurance company would sting me badly if I told them it had one fitted, even though its only being used to hold the boost down. JB Quote Link to comment Share on other sites More sharing options...
Guest Ash Posted November 20, 2001 Share Posted November 20, 2001 You know, I just never understood this "boost-creep" nonsense. Properly fitted, a boost controller will regulate boost from the stock boost caused by the actuation of the pod only to whatever is set on the controller. Well, that is my experience. The only cars that I ever came across that could not regulate boost have had some kind of fault. Either the wastegate was stuck closed (as happened in my case) or the boost controller was fitted incorrectly, or whatever. Yours, J Quote Link to comment Share on other sites More sharing options...
Alex Posted November 21, 2001 Share Posted November 21, 2001 Hmm with that in mind when I de-cat mine (which has now been out back) I will see if my SBC-iD can hold the boost down to 1 bar. If these wast gates are the main problem is there something we should all do about them? Can we replace them? Tighten the up? I don't even know where mine is to check it....so I'm not sure how it will affect things!! Can you get higher quility (or "race") wastgates which can help us control the boost better??? Quote Link to comment Share on other sites More sharing options...
Gareth Davies Posted November 21, 2001 Share Posted November 21, 2001 Hmm JIC stated the cats had been removed... not that that proves anything. It definatly would explain the MOT passable emissions when we rolling roaded it. What does confuse me though is that if the controller is higher, the boost goes higher simple as that. I've had it at 60 and I backed off as it was going past 1.3 bar. So inversly having it set lower does lower the maximum boost, however all my settings are wrong at the moment as I believe the cold air is allowing it to boost faster/higher so the controller doesn't catch it. I'm not saying this works to extremes, since doesn't Justin have serious over boost problems with an AVC controller? I really do need to find an idiots guide to car modding (Max power is to advanced for me ) that explains what a boost controller does, since I was stupid enough to think that it controlled boost :biggrin: Quote Link to comment Share on other sites More sharing options...
Doughie Posted November 21, 2001 Share Posted November 21, 2001 Gareth I have seen somewhere a URL which has a pretty good guide to the DSBC and how to set it up etc. I can try to find it if you want. Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted November 21, 2001 Share Posted November 21, 2001 Quote: from Gareth Davies on 1:55 pm on Nov. 21, 2001[br] What does confuse me though is that if the controller is higher, the boost goes higher simple as that. I've had it at 60 and I backed off as it was going past 1.3 bar. You don't need your cats removed to run high boost, it just helps as they are such a restriction. Quote Link to comment Share on other sites More sharing options...
Gareth Davies Posted November 21, 2001 Share Posted November 21, 2001 Doughie, I've got the online manual thanks. It's just it seems fundamentally people are saying the boost controller doesn't do what I thought it did! Oh well, it does what is says on the tin for me so i'm happy. Maybe i'll dump the boost "controller" (paperweight) and fit a bleed valve like real men Guess I just need to work out if the car has cats or not!. Heres hoping it does (so I can take them out and get more Puwah! Muhahaha). *Slap* Sorry got a bit carried away there... Quote Link to comment Share on other sites More sharing options...
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