arne Posted May 10, 2013 Share Posted May 10, 2013 what's the diameter of a 1bar RR? or does it only makes a difference without BC? Quote Link to comment Share on other sites More sharing options...
Guest Budz86 Posted May 10, 2013 Share Posted May 10, 2013 Strangely it varies depending on the car. Think Whifbitz have a few different sizes so may be worth speaking to Paul Quote Link to comment Share on other sites More sharing options...
tony tt Posted May 10, 2013 Share Posted May 10, 2013 If go for a 1 bar restrictor ring to be safe then raise to 1.2 with a bc. Paul whiffin sells both sizes I'm sure. Quote Link to comment Share on other sites More sharing options...
arne Posted May 10, 2013 Share Posted May 10, 2013 I don't get why to run on 1.2bar with a 1bar RR? Quote Link to comment Share on other sites More sharing options...
Wez Posted May 10, 2013 Share Posted May 10, 2013 This whole debate is as old as this forum A restrictor ring is not an exact science and is a bodge to fix the simple flaw that the internal wastegates are not able to control boost properly on the JSpec units. RR are sold as 1bar but do not guarantee 1bar boost, there are lots of factors, ie the weather, on a hot day it will make less and a cold frosty morning it will make more due to the dense air. Its long been said that 1.2bar is the max safe boost on the JSpec turbos, to safely achieve this fitting a restrictor ring to give approx 1bar allows for variables like the mentioned weather, you can then safely raise the boost to 1.2bar with a boost controller. If for example you fitted a 1.2bar restrictor ring on a nice warm day, 100% guaranteed when you went out on a nice cold morning and booted it you would overshoot and possibly det the engine, blow the turbos or cause any other number of damage. Now some people ask, why 1.2bar, I see two reasons for this, firstly the JSpec ceramic units do not like overspeed and tend to fail, secondly the JSpec is MAP not MAF and the stock MAP sensor reads to just over 1.2bar, therefore when you are out of the MAP range you are leaving your fueling to the hands of the gods and relying on your fuel reg to supply more fuel with higher boost, not an ideal situation. Quote Link to comment Share on other sites More sharing options...
arne Posted May 10, 2013 Share Posted May 10, 2013 do you mean that if my BC is running 1.2 bar and I have a 1bar RR that my TURBO'S will never reach 1.2bar but rather 1bar? if so, does this mean that running 1.4 bar boost with a 1.2 bar RR is also safe? Quote Link to comment Share on other sites More sharing options...
Wez Posted May 10, 2013 Share Posted May 10, 2013 do you mean that if my BC is running 1.2 bar and I have a 1bar RR that my TURBO'S will never reach 1.2bar but rather 1bar? if so, does this mean that running 1.4 bar boost with a 1.2 bar RR is also safe? That is not what I mean at all. I assume you have a boost gauge, with a 1 Bar restrictor ring and boost controller set 1.2bar you should be running 1.2bar as verified by the boost gauge read out, if you didnt have a 1 bar restrictor ring you would not be able to run 1.2bar safely, boost controllers can only increase boost, not reduce it, without the 1 bar restrictor your boost would over shoot 1.2 bar and your controller would be useless Quote Link to comment Share on other sites More sharing options...
arne Posted May 12, 2013 Share Posted May 12, 2013 I'm running 1.05 bar and I don't know what restrictor ring I have... I was wondering if I make the hole bigger... will it be safe? And what will be the best diameter of the "hole" to have max power but be safe enough...? Quote Link to comment Share on other sites More sharing options...
Guest Toddzor Posted October 2, 2013 Share Posted October 2, 2013 Hey guys, Sorry to revive a somewhat older thread. Just a quick question on the topic of the BPU. I own JDM - so, I'm going to need to restrictive ring. My question is in regards to the boost controller. Although not necessary - wouldn't a constant 1.2 bar eventually put strain on the jdm turbos? Or are they perfectly fine running at 1.2 bar all day every day? Would you suggest getting a smaller ring for say 0.9 bar, and getting a boost controller to up the boost to 1.2? I'll stick with just the RR if anyone can confirm that 1.2 bar is perfectly safe to run daily. Quote Link to comment Share on other sites More sharing options...
listy Posted October 2, 2013 Share Posted October 2, 2013 Read the thread Get a 1 bar restrictor ring, not a 1.2 bar one. I run just a 1 bar RR at the moment, as my Boost Controller gave up a while back. On colder days, I boost to 1.1 bar (ish), so having a 1 bar RR as apposed to a 1.2 bar RR is saving my tubbies. A RR and boost controller is the safest way to run higher boost. I would never dream of runng at 1.2 bar with no boost controller. 1.2 bar is the recognised safe limit for J Spec turbos, so should be fine at 1.2 bar. Don't forget, you will only hit 1.2 bar when you're going some. To sum up: Fit a 1 bar RR, and a boost controller. Set the BC to 1.2 bar, and enjoy Quote Link to comment Share on other sites More sharing options...
Guest Toddzor Posted October 2, 2013 Share Posted October 2, 2013 No worries! Thanks for that Listy Quote Link to comment Share on other sites More sharing options...
p1RATE Posted November 5, 2013 Share Posted November 5, 2013 I thought this would be the best place to ask as i know this is a common topic but i cant find much information on this. I have seen in a number of places people talking about a BPU N/A. What would this consist of? i was under the impression that there was not much that you could do with an N/A other than fit a less restrictive exhaust. Quote Link to comment Share on other sites More sharing options...
Gaz6002 Posted November 5, 2013 Share Posted November 5, 2013 You can do similar mods on an NA - and almost any car, actually - but you won't see the same gains. BPU is a term coined for TT Supras, NA owners just like to kid themselves about what they're driving Quote Link to comment Share on other sites More sharing options...
Guest Toddzor Posted January 15, 2014 Share Posted January 15, 2014 (edited) Just a quick question. I have a FMIC intercooler, and have deleted the first CAT with a 3' pipe. This leaves the stock midpipe in place. I am still overboosting and am getting 22psi which is obviously hurting my AFR (12.7 to be exact). I thought maybe the stock midpipe would be small enough, and therefore wouldnt need a restrictor ring. Does anyone know the size of the stock midpipe? Thanks Edited January 15, 2014 by Toddzor (see edit history) Quote Link to comment Share on other sites More sharing options...
Guest supra&starlet Posted February 26, 2014 Share Posted February 26, 2014 i had an aftermarket fuel pump in my gas tank, and i got that removed (the shop kept the aftermarket pump , ) anyways. Right now is a healthy J-spec fuel pump in the tank. Car is bpu, i am just wondering if i will be safe with this fuel pump for running no more than 1.0BAR of boost?? Or will i need to change the fuel pump if i plan to run that OR, What is the boost range that the JDM fuel pump will take before you start running lean, ect.. Quote Link to comment Share on other sites More sharing options...
Guest Budz86 Posted February 26, 2014 Share Posted February 26, 2014 You could be running quite lean at some points on WOT so it would be safer to upgrade the pump. Was the J spec pump new or second hand? Stock boost cut was set at 1 bar due to lack of fuel beyond that. Bear in mind that on some days (cold ones mostly) you may exceed 1 bar. How are you controlling and measuring boost? Do you have an AFR gauge? Quote Link to comment Share on other sites More sharing options...
Silece2k6 Posted July 3, 2014 Share Posted July 3, 2014 Sorry, maybe I dont understand. Ive got a 95 Jspec TT 6Spd with Catback, HKS Intake and Greddy Intercooler. What can I expect if I only decat the 1st or 2nd Cat? (not both, because of Police ) Provided FCD, Plugs and Fuelpump thank you Patrick Quote Link to comment Share on other sites More sharing options...
pete.osborne69 Posted November 29, 2014 Share Posted November 29, 2014 So I'm going bpu, but I am waiting on a fcd and boost gauge to arrive, I have everything else, would I be able to fit everything and still be able to drive the car or should I wait until the fcd arrives (no ETA) and if it is safe to drive what would I be limited to so I don't hit fuel cut, I assume no putting foot down for a long period of time but how hard do I have to accelerate to hit this fuel cut (not that I want to, just need some space in my living room for Xmas but this car is my only means of transportation) Thanks Pete Quote Link to comment Share on other sites More sharing options...
Grasmt Posted November 29, 2014 Share Posted November 29, 2014 The restrictor ring in the exhaust will hold the boost to 1bar, you dont need the fcd to run at 1bar as it cuts when boost exceeds that. Im running bpu @1bar with no fuel cut no boost controller only the restrictor ring in the exhaust and ive had no issues Quote Link to comment Share on other sites More sharing options...
pete.osborne69 Posted November 30, 2014 Share Posted November 30, 2014 Thanks will get it all fitted today then Quote Link to comment Share on other sites More sharing options...
pete.osborne69 Posted November 30, 2014 Share Posted November 30, 2014 does anybody know how to fit walbro pumps to the stock hanger Quote Link to comment Share on other sites More sharing options...
Nic Posted November 30, 2014 Share Posted November 30, 2014 does anybody know how to fit walbro pumps to the stock hanger Which Walbro pump have you bought? if it's the correct one it should be a straight swap, the UK and J-spec hangers are different so you'll need the right pump for your car. J-spec = GSS342 Walbro Fuel Pump UK Spec = GSS341 Walbro Fuel Pump Quote Link to comment Share on other sites More sharing options...
pete.osborne69 Posted November 30, 2014 Share Posted November 30, 2014 Thant explains a lot I have bought the UK spec one off someone on here and I have j-spec, explains why it didn't fit, and now I know there are two different types Quote Link to comment Share on other sites More sharing options...
Mk4Gaz Posted November 30, 2014 Share Posted November 30, 2014 It does fit a jspec Pete, I had it on mine. What bit are you struggling with? Quote Link to comment Share on other sites More sharing options...
Nic Posted November 30, 2014 Share Posted November 30, 2014 The fit is back to front on a UK spec, you can make it fit but I think you'll need a jubilee clip around the pump to hold it onto the hanger. Quote Link to comment Share on other sites More sharing options...
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