jaymdee Posted December 6, 2004 Share Posted December 6, 2004 Hi; this is bugging me and I can't work out why: I have recently had an RSR exhaust and full decat fitted, but I am only achieving 1.0Bar boost. With the Baffle in, I am limited to 0.8 Bar. The car is a ’95 J-spec, so I was hoping for a good 1.2Bar with the Baffle out. I have checked all the pipe work, replaced the BOV with another stock BOV (very kindly provided by Jake - cheers!), but still cannot get 1.2Bar. I have tested the system in TTC (using vacuum hose method) – this gave 1.1Bar dropping to 0.8Bar (baffle in due to noise). When I set it back to Seq mode (3 hours later), there was a satisfying psst of air, so I am assuming that the system is pressurising & holding pressure. (i've also tried 2 boost gauges) Using the ‘bleeder T’ mod, I can get well over 1Bar (went like a rocket!), but I think it would overboost if I didn’t limit my right foot, so did not floor it. My only thought now is that my car does not follow the standard J-spec decat rules (wastegate bleeding more exhaust than normal?). Options to try are another dump valve; removing the restrictor ring or fitting a bleed valve. Any suggestions??? I believe Chris Wilson does a bleed valve, which I may be intersested in. I did try a manual boost controller, but found it to be unstable, and don't really want more electronics on the dash, so am looking to avoid an EBC. cheers J:confused: Link to comment Share on other sites More sharing options...
paul mac Posted December 6, 2004 Share Posted December 6, 2004 jaymdee it sounds like everything on your car is working fine, there are no hard and fast rules when it comes to the boost you will get when fitting de-cats and exhausts, everyone assumes that you will automatically get 1.2 bar, with full a de-cat and super dragger mine makes just under 1.1 when its hot and just over 1.1 in the winter, if you want more than the 1 bar you have you could try removing the restrictor ring and see what it boosts to, dont worry if it hits 1.4 bar it wont do it any harm just the once, you could then file a bit of the ring out and keep trying it till you are happy but remember without having a "smart" boost controller (as opposed to a bleeder valve) you will allways be prone to fluctuating boost levels with the seasons, can you trust the gauges you have tried, when i bought a second hand hks gauge i calibrated it at work as we have the gear and it was 0.8 bar out, lastly it may sound simple but have you checked all your intercooler pipework, hope my ramble helps Link to comment Share on other sites More sharing options...
jaymdee Posted December 6, 2004 Author Share Posted December 6, 2004 Cheers for reply Paul, Have not checked all the connections down low, as I don't have facilities, but have checked all the others. As the boost varies with baffle in/out (0.8/1.0), I think it's all ok, just not reaching the higher level of boost I'm looking for. If you reckon hitting 1.4 on a single occasion may be ok, I'll have a look to see how high the boost goes with the Bleeder T. Really I'd like some way of adjusting the amount of air p**sing out of it though. Gauge out by 0.8Bar!! Imagine thinking you're hitting 1.2Bar and it's really 2.0Bar!!! TAXI!!! J:) Link to comment Share on other sites More sharing options...
tbourner Posted December 6, 2004 Share Posted December 6, 2004 And my guage was £40!!! Wonder how far out that is then!! Link to comment Share on other sites More sharing options...
paul mac Posted December 6, 2004 Share Posted December 6, 2004 Originally posted by jaymdee If you reckon hitting 1.4 on a single occasion may be ok, I'll have a look to see how high the boost goes with the Bleeder T. Really I'd like some way of adjusting the amount of air p**sing out of it though. Gauge out by 0.8Bar!! Imagine thinking you're hitting 1.2Bar and it's really 2.0Bar!!! TAXI!!! some guys on the forum have been running 1.4 on stock j-specs i dont know how long they last at that level but if you want to keep it safe a couple of runs wont do it any harm, the only trouble is you may get a taste for that kind of power level, you can get proper bleeder valves demon tweeks do them, and sorry my boost gauge was'nt 0.8 bar out i meant 0.08 (nearly 0.1) at 0.8 out i think the gauge would have been in the bin Link to comment Share on other sites More sharing options...
jaymdee Posted December 6, 2004 Author Share Posted December 6, 2004 Aahh, 0.08 makes more sense. A bit worrying otherwise - 40% error margin!! Will give running it a go and see how high the boost gets. I have put bid on 3 way bleed valve on Ebay anyway I'll get it sorted one way or another. The restrictor ring may be the best thing to do, especially as it's the right time of year as the boost will only go down when it's a bit warmer. J:) Link to comment Share on other sites More sharing options...
tbourner Posted December 6, 2004 Share Posted December 6, 2004 Think Dude was running >1.4bar on his stock japs. Apparently they let go on low boost though (damaged by higher boost obviously). Dunno how long he ran them at 1.4+ for. Link to comment Share on other sites More sharing options...
Steve W2 Posted December 6, 2004 Share Posted December 6, 2004 Unless Chris Wilson has drilled the orifice plate out knowing the exact increase in flow caused by your exhaust and decat it will only be a rough guess based on his experience. If you are hitting those sort of boost levels with the restrictor ring in, file it out as others have said. Its trial and error until you get the boost levels you want. Link to comment Share on other sites More sharing options...
jaymdee Posted December 7, 2004 Author Share Posted December 7, 2004 Cheers Steve. I think it should be simple to sort. I was a bit concerned that maybe the system wasn't holding pressure, but since trying the TTC mod, and it holding OK, I'm happier that the car seems ok, just a matter of finding the correct restrictor ring diameter J:) Link to comment Share on other sites More sharing options...
Steve W2 Posted December 7, 2004 Share Posted December 7, 2004 If somebody can give me an elemental analysis of the exhaust gas, and the flowrate, I can work out the orifice area for you:cool: Link to comment Share on other sites More sharing options...
Barnstormer Posted December 7, 2004 Share Posted December 7, 2004 I too have had a similar experience to yours. I have an RSR, double decat with 3" pipework with a CW restrictor ring (dia 52mm). With the baffle in getting 0.8-0.85, baffle out around 1.0 -1.05 bar. Haven't tried with the restrictor ring yet but it may mean that we don't need it. I also have a Blitz boost controller that I may consider fitting to up the boost to around 1.2 bar. ATB Gavin Link to comment Share on other sites More sharing options...
jaymdee Posted December 7, 2004 Author Share Posted December 7, 2004 Originally posted by Steve W2 If somebody can give me an elemental analysis of the exhaust gas, and the flowrate, I can work out the orifice area for you:cool: Sorry Steve, Is this particular to my car? I'm not sure how to provide this information. Was assuming trial and error J:conf: Link to comment Share on other sites More sharing options...
jaymdee Posted December 7, 2004 Author Share Posted December 7, 2004 Originally posted by Barnstormer I too have had a similar experience to yours. I have an RSR, double decat with 3" pipework with a CW restrictor ring (dia 52mm). With the baffle in getting 0.8-0.85, baffle out around 1.0 -1.05 bar. Haven't tried with the restrictor ring yet but it may mean that we don't need it. I also have a Blitz boost controller that I may consider fitting to up the boost to around 1.2 bar. ATB Gavin Gavin, interesting that someone else has this, as most people seem to get 1.4-1.5 Bar without restrictor ring and need it to limit boost to 1.2. When I tried the Bleeder T mod, the extra performance was electric. Much more like it!!! May consider increasing the RR to 2.25 inch, see what happens J:) Link to comment Share on other sites More sharing options...
Steve W2 Posted December 7, 2004 Share Posted December 7, 2004 Originally posted by jaymdee Gavin, interesting that someone else has this, as most people seem to get 1.4-1.5 Bar without restrictor ring and need it to limit boost to 1.2. When I tried the Bleeder T mod, the extra performance was electric. Much more like it!!! May consider increasing the RR to 2.25 inch, see what happens J:) You guys may get the same, have either of you tried? All you have done is remove the original restrictions limiting boost (cats and original exhaust) and added a new restriction. If the plate has been drilled to small you will restrict boost, why don't you try taking it out and see waht you get. I would bet its at least 1.2 1.3 Bar. All cars will be slightly different but they should still generate similar boost under similar conditions. I was saying that if someone can give me the typical exhaust gas composition for the Supra and the max required flowrate I could calculate the orifice area. I would be impressed if anyone could be give me the above though. Link to comment Share on other sites More sharing options...
jaymdee Posted December 8, 2004 Author Share Posted December 8, 2004 Sorry Steve, but I can't and not sure if anyone else will be able to. Thanks for offer to work this out, but I'll try your suggestion of removing it and see what I get. J Link to comment Share on other sites More sharing options...
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