Supra-Iceman Posted April 5, 2007 Share Posted April 5, 2007 If you still have both cats in place , Is it possible to raise the boost to 1.2Bar or more with a electronic boost controller like the Apexi AVC-R ?? Thanks for all inputs Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted April 5, 2007 Share Posted April 5, 2007 Yes! but you won't do the turbos or engine any favors, EGTs will go very high and you will likely be getting some detonation, you also won't get much increase in power due to the reasons already mentioned, not advisable. Quote Link to comment Share on other sites More sharing options...
Pete Posted April 5, 2007 Share Posted April 5, 2007 Your cats will probably not last too long either. Quote Link to comment Share on other sites More sharing options...
spidermonkey Posted April 5, 2007 Share Posted April 5, 2007 How about the 1st cat still in place *sorry for the hijack* Quote Link to comment Share on other sites More sharing options...
Sharpie Posted April 5, 2007 Share Posted April 5, 2007 How about the 1st cat still in place *sorry for the hijack* Yes, and this is how TDI would only do it. Well, 5+ years ago now.... Quote Link to comment Share on other sites More sharing options...
spidermonkey Posted April 5, 2007 Share Posted April 5, 2007 Yes, and this is how TDI would only do it. Well, 5+ years ago now.... i have my MOT next week so would it be a good idea for a full de-cat after that? (i only run my tubbies at 1.2bar occasionally ) Quote Link to comment Share on other sites More sharing options...
dandan Posted April 5, 2007 Share Posted April 5, 2007 Full decat and restrictor ring to take you down to 1.1 or 1.2, depends how much of a gambling man you are. Hopefully this link will show you performance at 1.1bar with 1st cat still in place compared to full decat at 1.1 bar with restrictor ring: http://www.mkivsupra.net/vbb/showpost.php?p=1344590&postcount=16 Quote Link to comment Share on other sites More sharing options...
spidermonkey Posted April 5, 2007 Share Posted April 5, 2007 Full decat and restrictor ring to take you down to 1.1 or 1.2, depends how much of a gambling man you are. Hopefully this link will show you performance at 1.1bar with 1st cat still in place compared to full decat at 1.1 bar with restrictor ring: http://www.mkivsupra.net/vbb/showpost.php?p=1344590&postcount=16 Top bloke, I would probably size the restrictor to cap the turbo's to 1 bar and set the boost controller to 1.1 & 1.2 bar, thanks for the answers all *sorry again for the hijack* Quote Link to comment Share on other sites More sharing options...
cheekymonkey Posted April 5, 2007 Share Posted April 5, 2007 Top bloke, I would probably size the restrictor to cap the turbo's to 1 bar and set the boost controller to 1.1 & 1.2 bar, thanks for the answers all *sorry again for the hijack* 'scuse my ignorance guv but this seems counter-intuitive to me. If you're restricting the airflow out the back with a RR to 1 bar and then telling the turbo to supply 1.1 or 1.2 bar, what happens to that extra pressure? In my mind, putting in a RR at 1.2 bar then setting the boost controller to whatever you want , 0.9, 1.1 etc ensures that you won't get above 1.2 bar by mistake. So tell me, what am I missing here Quote Link to comment Share on other sites More sharing options...
mikeyb10supra Posted April 5, 2007 Share Posted April 5, 2007 'scuse my ignorance guv but this seems counter-intuitive to me. If you're restricting the airflow out the back with a RR to 1 bar and then telling the turbo to supply 1.1 or 1.2 bar, what happens to that extra pressure? In my mind, putting in a RR at 1.2 bar then setting the boost controller to whatever you want , 0.9, 1.1 etc ensures that you won't get above 1.2 bar by mistake. So tell me, what am I missing here A boost controller raises boost, not holds it Its never a good idea to increase boost with a resistance in place, Ie Cats, your only going to run up a huge EGT's and really stress the turbos as there spinning much harder and against more resistance, not a good combination Quote Link to comment Share on other sites More sharing options...
cheekymonkey Posted April 5, 2007 Share Posted April 5, 2007 A boost controller raises boost, not holds it Its never a good idea to increase boost with a resistance in place, Ie Cats, your only going to run up a huge EGT's and really stress the turbos as there spinning much harder and against more resistance, not a good combination OK, but that still seems like what I was saying is correct. I'd be boosting to 1.1 bar, the only resistance being a RR sized for 1.2 bar, i.e. not much resistance at all. If it was the other way round, there'd be more resistance, surely? Quote Link to comment Share on other sites More sharing options...
dandan Posted April 5, 2007 Share Posted April 5, 2007 You can't set your restrictor ring for 1.2bar and then magically drop that to 1.1 with a boost controller. Quote Link to comment Share on other sites More sharing options...
mikeyb10supra Posted April 5, 2007 Share Posted April 5, 2007 OK, but that still seems like what I was saying is correct. I'd be boosting to 1.1 bar, the only resistance being a RR sized for 1.2 bar, i.e. not much resistance at all. If it was the other way round, there'd be more resistance, surely? A j-spec needs some form of resistance to work against otherwise the stock wastegate is overpowered, hence the 1.2 RR being used, this acts as the resistance, if this was not there and no cats in place there would be silly amount of boost and mega spikes when on full chat as the wastegate remains open constantly! UK's have stronger Wastegate springs so the RR is not needed but a boost controller is to raise it What bit are you finding confusing?? Quote Link to comment Share on other sites More sharing options...
spidermonkey Posted April 5, 2007 Share Posted April 5, 2007 'scuse my ignorance guv but this seems counter-intuitive to me. If you're restricting the airflow out the back with a RR to 1 bar and then telling the turbo to supply 1.1 or 1.2 bar, what happens to that extra pressure? In my mind, putting in a RR at 1.2 bar then setting the boost controller to whatever you want , 0.9, 1.1 etc ensures that you won't get above 1.2 bar by mistake. So tell me, what am I missing here I run my car normally at 1 bar, but like to have the options to run at 1.1 or 1.2 now and again, but i'm worried about creating alot of heat when running higher boost as the b/c can only raise boost i like to keep the car at a reliable 1 bar - hope this explains Quote Link to comment Share on other sites More sharing options...
dandan Posted April 5, 2007 Share Posted April 5, 2007 It's not the wastegate spring that's the problem. It's the fact that the actual wastegate itself can only flow so much and on a J spec the "hole" (which is the open wastegate) is not big enough to bypass enough exhaust to keep the boost down. Quote Link to comment Share on other sites More sharing options...
cheekymonkey Posted April 5, 2007 Share Posted April 5, 2007 A j-spec needs some form of resistance to work against otherwise the stock wastegate is overpowered, hence the 1.2 RR being used, this acts as the resistance, if this was not there and no cats in place there would be silly amount of boost and mega spikes when on full chat as the wastegate remains open constantly! UK's have stronger Wastegate springs so the RR is not needed but a boost controller is to raise it What bit are you finding confusing?? I guess that pretty much clears it up for me, still a little confused though about how it all works. The whole reason I ask is that the car I am buying has a boost controller (blitz dual SBC), and the second cat is out because of an aftermarket exhaust system - and it's apparently run at 0.9 bar and no higher - apart from that it's stock. No idea if it would have an RR already installed but I would check. Basically just wonder what's the point of the boost controller on a J-spec if you have to use an RR to get the amount of boost you need. There must have been reason to fit it in the first place Quote Link to comment Share on other sites More sharing options...
spidermonkey Posted April 5, 2007 Share Posted April 5, 2007 R rings can be tempremental (ie trying to get the size right) if you are trying to get a constant 1.2 bar you may get 1.3/1.4 bar on colder days, if this happens on my car i can turn the boost controller down to suit, its each to their own i think, would you like to spend a couple of quid on a 1.2 bar r/ring (with decat) or a couple of hundred on 1 bar r/ring (with decat) and boost controller to get 1.2 bar Quote Link to comment Share on other sites More sharing options...
cheekymonkey Posted April 5, 2007 Share Posted April 5, 2007 R rings can be tempremental (ie trying to get the size right) if you are trying to get a constant 1.2 bar you may get 1.3/1.4 bar on colder days, if this happens on my car i can turn the boost controller down to suit, its each to their own i think, would you like to spend a couple of quid on a 1.2 bar r/ring (with decat) or a couple of hundred on 1 bar r/ring (with decat) and boost controller to get 1.2 bar Well exactly, I know what I would do, but some random Japanese person must have wanted that boost controller really badly *grin* Quote Link to comment Share on other sites More sharing options...
Nic Posted April 6, 2007 Share Posted April 6, 2007 I'd fit a 1bar RR and use a boost controller to raise as needed. Boost will vary a little between summer and winter temps. A boost controller will let you compensate for this. A boost controller with gain feature will also help the turbos spool up quicker. Some boost controllers also allow you to map boost settings against speed, so you maximise boost through each gear. Quote Link to comment Share on other sites More sharing options...
dandan Posted April 6, 2007 Share Posted April 6, 2007 Good point Nic. The gain feature can make a very noticeable difference to mid range torque helping to spin the tubbies up quicker... Quote Link to comment Share on other sites More sharing options...
CJ Posted April 6, 2007 Share Posted April 6, 2007 A long time ago I asked a question that nobody could answer and now that we are talking of RR's again, I will bring it back up - so to speak. I used to run a 1.0 bar RR and a boost controller. Whenever i set the BC to 1.2 bar, it worked fine and dandy but I found an anomaly that really scared me. I decided to try the "true twin" mod (running both to come on together) and found that the boost pressure went through the roof. I turned off the BC and was finding that I hit 1.5 and 1.6 bar So, can someone explain why the RR didn't do what we all assume they are supposed to? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted April 6, 2007 Share Posted April 6, 2007 Sounds suspiciously like you had a VSV or actuator problem, so you were making 1.2 on the first turbo, but when in TTC mode the second was coming in making more boost, that or your boost controller was plumbed in wrong. Quote Link to comment Share on other sites More sharing options...
CJ Posted April 6, 2007 Share Posted April 6, 2007 Sounds suspiciously like you had a VSV or actuator problem, so you where making 1.2 on the first turbo, but when in TTC mode the second was coming in making more boost, that or your boost controller was plumbed in wrong. I think you are missing the point here. I ran in it sequential mode and it boosted up normally with the first and second turbo's kicking in when they should and 1.2 bar of boost showing. It was when I took the BC offline i.e turned it off and then ran in True Twin mode that it happened. My point being, if the restrictor ring is set to limit the boost to 1.0 bar then how come, with no boost controller operating, the boost went sky high to 1.5 / 1.6 bar? Either the thing does the job or it doesn't. Quote Link to comment Share on other sites More sharing options...
letmeshowyou Posted April 6, 2007 Share Posted April 6, 2007 CJ, did it get to 1.5bar and stay there, or just spike to that figure? boost spikes are a problem when running true twin. Quote Link to comment Share on other sites More sharing options...
CJ Posted April 6, 2007 Share Posted April 6, 2007 CJ, did it get to 1.5bar and stay there, or just spike to that figure? boost spikes are a problem when running true twin. I don't quite understand why there should be a difference between a spike or normal. If the restrictor ring is supposed to stop boost going above 1.00 bar then surely that is what it should do. Quote Link to comment Share on other sites More sharing options...
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