Vaughany Posted January 31, 2004 Share Posted January 31, 2004 Hi everyone I need abit of advice, I have done the usual mods, exhaust, Induction Kit, 2nd Cat out. I am now looking to progress further. I am aware that the next option is first cat out, fuel cut, boost controller raising the boost to 1.2 bar. Total price in the region of £1200. However, this is where I ned the advice, would it be better to miss all this out and just purchase a mappable ECU such as Motec system. I know this is more expensive but I have been led to believe that this is better and safer for the vehicle. Can anyone spread some light on this. I know with a ECU, the car will have to be remapped everytime I want to adjust the boost. I am thinking though that I could just run the optimal boost all the time. If the car is mapped correctly then there will not be a requirement to lower the boost etc due to weather conditions that may effect the boost pressure. I was talking to a gentlemen who builds rally cars. This is what he suggests as he said that the car is totally reprogrammed to run efficiently and safe all the time. Please let me know what you all think. Cheers Quote Link to comment Share on other sites More sharing options...
JamesG Posted January 31, 2004 Share Posted January 31, 2004 What you decide to do depends, in some respects, on whether you have a UK or Jap spec Supra. With a UK supra, you will benefit from faster turbo spool-up with both cats out. This is also the case with the Jap supra but you will have to put a restrictor back in the exhaust (though less restrictive than the first cat) to stop the car overboosting. This is because the Jap supra's wastegate is too small. You can't solve this with electronics (even a mappable ECU). Once this is done, it would (arguably) be better to replace the ECU and have it mapped properly. However, I think most people would agree this is overkill for standard turbos. Having a fuel-cut device isn't ideal for various reasons, but the supra can provide fuelling up to 1.2 bar. It's worth having it checked though. Not sure what you mean about the car having to be remapped everytime you want to adjust the boost. A fuelling map (for a turbocharged car) in an ECU will typically be rpm against manifold pressure. The fuel will be set correctly for all speed/load combinations up to certain limits. As long as the manifold pressure (boost) does not go beyond the range of the map, fuelling will be correct. Are you thinking about having to adjust a boost controller in different temperatures? This is where an aftermarket ECU *may* be better. If set up properly, you can have good closed-loop control so that a similar level of maximum boost will be gained whatever the ambient temperature. I'm not sure how good add-on boost controllers are in this respect. I have a Blitz DBSC and the maximum boost does change a bit in different conditions. Another interesting point, is how good is the standard Supra boost control at higher-than-standard boost levels? If it does a good job, then it seems a bit mad to bypass the standard control of the wastegate VSV with a boost controller. I keep meaning to do some practical tests of this, as my car has a bad flatspot around 3000-4000rpm that it didn't have before the Blitz DBSC was fitted. As you can probably tell from my ramblings, I think good boost control on the supra is actually pretty tricky, and might involve some trial-and-error no matter what method you go for. James. Quote Link to comment Share on other sites More sharing options...
Vaughany Posted January 31, 2004 Author Share Posted January 31, 2004 Hi James Thankls for the quick reply, just a quick question. Do I need to remove the 1st cat if I decide to fit a mappable ECU and if I dont what effect will this have on the car. What I want to achieve is raise the boost but get the correct fuelling etc and keep the car safe without any of the downfalls etc. Can this be achieved with a ECU upgrade or do I need to go the common route of Boost Controller, First Cat out, Fuel cut etc. My car is only running just short of 1 bar and I want to rise this to 1.2 bar. Can this be done by just removing the first cat and fitting a restrictor ring to stop over boosting. If this is the case why does everyone fit a boost controller? I know they allow you to turn the boost down but why do that if the car does'nt go above 1.2 bar. James I think I'm right on some bits and wrong on others. Please let me know what you think. Many thanks Quote Link to comment Share on other sites More sharing options...
Vaughany Posted January 31, 2004 Author Share Posted January 31, 2004 James Oh yeh I am driving a J-Spec Cheers Quote Link to comment Share on other sites More sharing options...
JamesG Posted January 31, 2004 Share Posted January 31, 2004 You don't need to remove the first cat at all. In fact, I believe Nathan, who was on this board a while ago and really knows his stuff, recommended the first cat be left in as it saves the hassle messing around with restrictor rings and problems passing the MOT emissions test. In this case, a boost controller can be added if necessary to increase the boost. Personally, I think the first step for your car would be to remove the first cat and add a restrictor ring. This can be sized such that the car goes to about 1.2 bar. Once this is done, you shouldn't really need a boost controller. It seems to me that it's a bit of a balancing act. You can have a large restriction that causes longer spool-up times, then increase max boost with a controller. Or you can have a restrictor ring and increase its diameter until just before you get overboost. This seems to be the best method to me, but I'm not sure how the max boost changes with different ambient temperatures. I think Chris Wilson has mentioned a manual bleed valve before. Perhaps this would give the best combination along with a correctly sized restrictor ring? James. Quote Link to comment Share on other sites More sharing options...
MONKEYmark Posted January 31, 2004 Share Posted January 31, 2004 why would you need a mapable ecu if you running 1.2 bar. the main thing would be to get your fueling checked out and make sure you not boosting too much. i have both cats out + blitz nurspec exhaust + cams. i am running on standard japanese injectors and fueling and no boost controller. i know i need to get fueling checked. seems a lot of people fit a super AFC to adjust fueling and get a fse/fpr and upgraded fuel pump. but to me a mapable ecu seems a bit overkill for standard turbos and expensive too. wait for an expert to pop along seems 1.2 - 1.3 bar seems to be the limit people stick to. though a couple of people run 1.4+ bar go get your fueling checked then you know where to go next Quote Link to comment Share on other sites More sharing options...
Vaughany Posted January 31, 2004 Author Share Posted January 31, 2004 Thanks for the advice everyone. The difficulty is that everyone has a different opinion. I am thinking about forgetting the ECU upgrade and going the other route. cheers Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 1, 2004 Share Posted February 1, 2004 In an ideal world, with a veru healthy budget to play with, I would always want to suggest a mappable ecu and a good boost gauge should be the VERY FIRST mods anyone makes, and then subsequent mods can be catered for totally correctly, timing and fuellig wise. As you need to remap every time you do any serious upgrade it would obviously make sense to do everything at the same time and only have to map it the once. VERY few people have, or are willing to invoke, that sort of budget however. There is no denying it's the correct approach though... The very fact you are considering this is good, Adding lots of bits of hardware, especially external, or cams is dead easy. Mapping the engine to take proper advantage of them is infinitely harder and more expensive and time consuming. Quote Link to comment Share on other sites More sharing options...
Vaughany Posted February 2, 2004 Author Share Posted February 2, 2004 Cheers Chris If you dont mind, I will contact you in the near future so we can discuss my next steps to achieve more performance. Thanks again Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 2, 2004 Share Posted February 2, 2004 No problem, contact details are in my sig. Thanks. Quote Link to comment Share on other sites More sharing options...
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