wkdtime Posted December 11, 2006 Share Posted December 11, 2006 These sort of threads keep popping up and people always seem to forget that not ALL JDM TT's over boost when fully decatted, why this is, no one knows ( I started a thread about this a while ago). My car is fully decatted, but only sees 1.0 Bar boost, i use an EBC to get it to 1.2 Bar etc, Nic is another example, and Kosmic. James, ditch the ring and see what you boost then, or keep the ring and get a Manual boost controller (A bit crude) or do it properly and get an Electronic Boost controller. For those who think EBC's are an over kill and not needed i say you are partially right, but for those cars like James's or mine an EBC makes one hell of a difference. How many people with restrictor rings see 1.2Bar in all gears? How many Underboost? How many over boost with higher loads, e.g higher gears? With an EBC dependent on model you can limit the boost to what ever you like in which ever gear, you can have quicker or slower spool up. The gains totally out weigh it's 'Cost' issues etc. A restrictor ring does exactly what it says on the can, 'It restricts the boost due to creating more back pressure' so you may hit 1.2 bar in 2nd gear and very well hit 1.4bar+ in 6th, or you may hit 0.9bar in 2nd and 1.2 bar in 6th. What it can't do is maintain the boost in each gear to the desired level e.g 1.2bar, this is where the boost controller wins hands down, It can control and maintain boost at any level between the minimum boost (i.e base boost level) to the maximum the EBC can deliver (Usually 2.5Bar) within in any speed or gear (Dependent on EBC model). Just beause your JDM spec does not 'Overboost' to 1.4Bar when fully decatted, it does not mean you have a problem. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 11, 2006 Share Posted December 11, 2006 There's almost certainly a boost leak or a control problem, I am seeing this more and more and more now the cars are elderly. You need to fix it rather than try and mask it with a boost controller. Quote Link to comment Share on other sites More sharing options...
wkdtime Posted December 11, 2006 Share Posted December 11, 2006 There's almost certainly a boost leak or a control problem, I am seeing this more and more and more now the cars are elderly. You need to fix it rather than try and mask it with a boost controller. Why does there have to be a probelm, there are a number of TT's fully decatted that do not require a Restrictor ring when fully decatted, mine being one of them. If it is a control problem, then it's a blessing in discguise as there is no need of a ring and you can use an EBC to have better control of boost rather than a crude method of limiting it. I have had mine on the rollers and made 390BHP ATF at 1.2Bar. No problems what so ever. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 11, 2006 Share Posted December 11, 2006 I haven't yet seen a J-Spec MKIV TT with a full decat and a free flowing "cat back" exhaust system, that DOESN'T need a restrictor ring to limit boost to below 1.2 bar, UNLESS it has tired turbos or another problem caused by leaks, VSV problems or a generally buggered engine. A boost controller often masks these problems, maybe even fixes them if the problem is with the first turbo VSV, but has never been required if the above problems are none existent, in my experience. Whether you should prefer an electronic boost controller, a restrictor ring, or a bleed valve is a different matter Quote Link to comment Share on other sites More sharing options...
mr keef Posted December 11, 2006 Share Posted December 11, 2006 I wasnt really impressed with BPU from standard until i put a big front mount intercooler on...to my car the change was amazing:) Quote Link to comment Share on other sites More sharing options...
wkdtime Posted December 11, 2006 Share Posted December 11, 2006 I haven't yet seen a J-Spec MKIV TT with a full decat and a free flowing "cat back" exhaust system, that DOESN'T need a restrictor ring to limit boost to below 1.2 bar, UNLESS it has tired turbos or another problem caused by leaks, VSV problems or a generally buggered engine. A boost controller often masks these problems, maybe even fixes them if the problem is with the first turbo VSV, but has never been required if the above problems are none existent, in my experience. Whether you should prefer an electronic boost controller, a restrictor ring, or a bleed valve is a different matter VSV's working fine here, how do i know? The car is running in TTC so VSV's are bypassed. Engine fine, how do i know? Compression test and leak down test carried out PRE BPU showed engine to be healthy, full boost comes in as expected 3900rpm, 390BHP ATF from dyno plot... Tired Turbo's? They have covered 58000 miles, no blue smoke, Pre BPU i had a healthy 0.85 Bar on stock engine Bar exhaust. Have i missed anything else? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 11, 2006 Share Posted December 11, 2006 wkdtime: Probably, without being funny. I used to put this down to production tolerances, but the few people who asked me to do a full and detailed search to see why their particular car was making less boost, de-catted, were shown faults that when fixed resulted in operation like the majority enjoyed. Most are happy to use a bleed valve or whatever to raise the boost, unless a buggered engine or turbo is the cause, where this will not really help. There are often few, if any, obvious downsides to raising the boost this way, save the possibility that not knowing WHY bugs you. If you are happy with your set up, then I am happy! Quote Link to comment Share on other sites More sharing options...
Sheefa Posted December 11, 2006 Share Posted December 11, 2006 I hope I don't have anymore boost leaks Chris Greg Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 11, 2006 Share Posted December 11, 2006 I hope I don't have anymore boost leaks Chris Greg If you stick to the conventional methods using sockets and spanners to remove your new I/C you should be OK, using kerbs and roundabout islands and suchlike for a faster job may cause future boost leaks detrimental to your wallet... Quote Link to comment Share on other sites More sharing options...
Sheefa Posted December 11, 2006 Share Posted December 11, 2006 Brilliant Chris. I shall note that point for future driving. Quote Link to comment Share on other sites More sharing options...
RobSheffield Posted December 11, 2006 Share Posted December 11, 2006 If you stick to the conventional methods using sockets and spanners to remove your new I/C you should be OK, using kerbs and roundabout islands and suchlike for a faster job may cause future boost leaks detrimental to your wallet... God, that made me chuckle Quote Link to comment Share on other sites More sharing options...
Stonkin Posted December 11, 2006 Share Posted December 11, 2006 Chris, i can understand exactly what you are saying, but, i also agree with wkdtime. My car is fully decatted, cat back exhaust, colder plugs, CW RR, FCD and yet will only boost to 1.0 bar, its only now that the weather is getting colder that the boost is starting to go up slightly. The car has been on the rollers, fuel is completely spot on, it made 320 rwhp at just under 1.0 bar (surrey rolling road, where many here have used) I havent tried removing the RR, to see what happens, i wasnt really too keen on the idea. I was happy to know that it runs what it does, and in the future i would just purchase a BC to up it to 1.2 when i need it. But as far as the guy at the rolling road and mark at phoenix think, the car is absolutely fine. But it doesnt run at 1.2 on daily use. But, surely the diameter needed on the rings is never going to be the same for every car? Close, but not spot on. Quote Link to comment Share on other sites More sharing options...
wkdtime Posted December 11, 2006 Share Posted December 11, 2006 Nope Stonkin, your Engine is either buggered or you have a leak. Or you may have a freak Supra like i do:D Quote Link to comment Share on other sites More sharing options...
Stonkin Posted December 11, 2006 Share Posted December 11, 2006 I prefer the freak theory, its a better comparison to its owner Quote Link to comment Share on other sites More sharing options...
Mas Posted December 11, 2006 Share Posted December 11, 2006 You can't be BPU until you get rid of both cats. No boost controller is required with a jspec. Once you are fully decatted you will need a restrictor ring to reduce boost to 1.2 bar. Without it you'll see 1.6 bar! Edit - do you have both cats on or not, or did your sig change?? How come?! Im fully decated and only running on 1 bar with restrictor ring!! thats why I now bought myself a boost controller to get as high as 1.2 bar. Quote Link to comment Share on other sites More sharing options...
Scoboblio Posted December 11, 2006 Share Posted December 11, 2006 Probably because your restrictor ring is smaller (if that's what you were asking). Quote Link to comment Share on other sites More sharing options...
wkdtime Posted December 11, 2006 Share Posted December 11, 2006 I have found a few members in N.Z who have the same problem with the some of the JDM's they have, atleast they dont call it a problem. From what i have gathered it's usually cars made in 1993-1994, the same in N.Z after a bit of research. Mines a 1994, Stonkin whats yours? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 11, 2006 Share Posted December 11, 2006 I also fall into the freak category, think i have posted a fair bit about this before, but with full decat etc i can only get .8 bar (.9 bar in cold weather) its doesn't matter if it is in sequential or TTC mode, the only way i can get more is to configure all the vac/pressure pipework to leave it running on just the the two std actuators, but i have recently reverted to the former as i was getting 1.45 bar peaks:( in the cold weather, so i am now thinking of going for a boost controller or similar, (see my bit in the "Boost Controller" thread) I to tested all the VSVs and all actuators etc, and compression and turbos are fine, and no leaks, and i still can't work it out? Quote Link to comment Share on other sites More sharing options...
wkdtime Posted December 11, 2006 Share Posted December 11, 2006 I also fall into the freak category, think i have posted a fair bit about this before, but with full decat etc i can only get .8 bar (.9 bar in cold weather) its doesn't matter if it is in sequential or TTC mode, the only way i can get more is to configure all the vac/pressure pipework to leave it running on just the the two std actuators, but i have recently reverted to the former as i was getting 1.45 bar peaks:( in the cold weather, so i am now thinking of going for a boost controller or similar, (see my bit in the "Boost Controller" thread) I to tested all the VSVs and all actuators etc, and compression and turbos are fine, and no leaks, and i still can't work it out? What year is your car, im trying to suss if this is more of issue with the pre 96 cars, i.e 93-94. I too have nothing wrong with my car, wel nothing a leak down test or compression test is showing, I have a new FMIC, and new vac pipes everywhere, Turbos are mint and well looked after, if there was a problem witht he engine, then surely it would have shown Pre BPU? i.e under boosting etc. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 11, 2006 Share Posted December 11, 2006 Yep another late 94 car:blink: the most frustrating thing is that despite all the testing i can find nothing, my only other thought was that it might be down to the ECU as this is what controls the VSVs switching. Quote Link to comment Share on other sites More sharing options...
wkdtime Posted December 11, 2006 Share Posted December 11, 2006 Yep another late 94 car:blink: the most frustrating thing is that despite all the testing i can find nothing, my only other thought was that it might be down to the ECU as this is what controls the VSVs switching. Im TTC, so no VSV's here, it runs the same in sequential. There are no adverse problems though, it boosts fine, no excess lag, even on the dyno plot you can see the boost come in when it should, i made 390BHP ATF at 1.2 bar, i know the engine is fine. ...It just doesn't over boost, doesn't spike, doesn't need a ring,... come to think of it... Quote Link to comment Share on other sites More sharing options...
imi Posted December 11, 2006 Share Posted December 11, 2006 interesting thread...... Quote Link to comment Share on other sites More sharing options...
RobSheffield Posted December 11, 2006 Share Posted December 11, 2006 See, im the other side of the story. Was running at 1.2 bar on a second decat pipe only, no boost controller. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 11, 2006 Share Posted December 11, 2006 Im TTC, so no VSV's here, it runs the same in sequential. There are no adverse problems though, it boosts fine, no excess lag, even on the dyno plot you can see the boost come in when it should, i made 390BHP ATF at 1.2 bar, i know the engine is fine. ...It just doesn't over boost, doesn't spike, doesn't need a ring,... come to think of it... Even in TTC mode there is a VSV/s operating, which is why i could only get over .8-.9bar after bypassing the last VSV. Quote Link to comment Share on other sites More sharing options...
Stonkin Posted December 11, 2006 Share Posted December 11, 2006 Mines a 1994, Stonkin whats yours? mines a 96 facelift, so there goes that theory Quote Link to comment Share on other sites More sharing options...
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