Ady Posted December 7, 2007 Share Posted December 7, 2007 Ive been speaking to some one who works with custom exhaust builds for years. He spends 24/7 making custom exhausts. Ive been talking about BPU with him and have come up with a diffrent idea to the norm. Rather than going for a double decatt with a 1.2 RR im thinking of decatting the first cat and adding in a top notch sports cat some where where the second cat would be on the stock system and leaving out the restrictor ring. Wont the sports cat provide some back pressure and also act as a restrictor? And I wont have to worry about MOT times as it should also pass the emmisions test. Please no silly replies on ''find a MOT place to overlook the emmisions'' - There is a VOSA van floating arround here now so dont want fines/points for something stupid. Wont it be pointless to put in a RR and a sports cat? Or will the sports cat just get trashed without a RR? Any technical lads out there who can offer some advice on this? Cheers Quote Link to comment Share on other sites More sharing options...
Gazboy Posted December 7, 2007 Share Posted December 7, 2007 Iirc a cat is now mandatory to go to the Nring as of January 2008 so if you have planned to go then it may be a wise investment. Quote Link to comment Share on other sites More sharing options...
tDR Posted December 7, 2007 Share Posted December 7, 2007 A decent sports cat would be a good solution to the requirement for some backpressure to stop the stock J spec turbos overspinning problem. It shouldn't be as restrictive as a stock cat but should be sufficiently restrictive so as to warrant not using a RR. Go for it but keep an eye on the boost once all fitted - you don't want more than 1.25bar tops, preferably 1.1bar. If it boosts to more than that then you'll need a RR to introduce more restriction and keep the boost at the level you want it. Cheers, Brian. Quote Link to comment Share on other sites More sharing options...
Ady Posted December 7, 2007 Author Share Posted December 7, 2007 A decent sports cat would be a good solution to the requirement for some backpressure to stop the stock J spec turbos overspinning problem. It shouldn't be as restrictive as a stock cat but should be sufficiently restrictive so as to warrant not using a RR. Go for it but keep an eye on the boost once all fitted - you don't want more than 1.25bar tops, preferably 1.1bar. If it boosts to more than that then you'll need a RR to introduce more restriction and keep the boost at the level you want it. Cheers, Brian. Hi Brian Thats what I thaught but just wanted some confirmation first before shedding out on a Sports Cat. I was thinking of tweeking the boost upto 1.1 Bar and not 1.2 Bar to see how it works. Last thing i was it to blow my turbos just for the sake of an extra 0.1 bar of boost. Ill be installing a boost gague so ill be able to monitor the boost pressure. For the sake of £15, should i throw in a 1.2 RR too as all the work is being done? Rather than getting the work done, overboosting and having to take it back to get a RR put in place? Cheers Quote Link to comment Share on other sites More sharing options...
tDR Posted December 7, 2007 Share Posted December 7, 2007 I think you'll be safe - the sports cat should be restrictive enough. The RR is a slag of a mod so better to leave it out if u can. Just get up to 2nd turbo RPM the 1st time u drive it and when you nail it, back off the throttle maybe 10% straight away to see where the boost is and then monitor your boost gauge as you apply the final 10%. You'll soon know whether you need a RR as well, but as I said I doubt it. Cheers, Brian. Quote Link to comment Share on other sites More sharing options...
Ady Posted December 7, 2007 Author Share Posted December 7, 2007 I think you'll be safe - the sports cat should be restrictive enough. The RR is a slag of a mod so better to leave it out if u can. Just get up to 2nd turbo RPM the 1st time u drive it and when you nail it, back off the throttle maybe 10% straight away to see where the boost is and then monitor your boost gauge as you apply the final 10%. You'll soon know whether you need a RR as well, but as I said I doubt it. Cheers, Brian. Cheers for that Brian - Ill go for it without a RR then and ill post up the results Do you think it will loose much BHP with using a sports cat as aooposed to no cats and a RR? Id rather have peace of mind over mot time and loose a few bhp........ Quote Link to comment Share on other sites More sharing options...
TrickTT Posted December 7, 2007 Share Posted December 7, 2007 Sounds a good idea, but the other reason for decatting is to reduce exhaust gas temperatures. It would be interesting to see how your sports cat compares to a normal decat + RR. Quote Link to comment Share on other sites More sharing options...
tDR Posted December 7, 2007 Share Posted December 7, 2007 Cheers for that Brian - Ill go for it without a RR then and ill post up the results Do you think it will loose much BHP with using a sports cat as aooposed to no cats and a RR? Id rather have peace of mind over mot time and loose a few bhp........ If the boost is similar, maybe a few bhp of a difference IMO - no biggy. People don't tend to go for sports cats because of the expense associated with them. TBH I can't see EGT's being much different than with a RR fitted - that tiny hole you introduce for the exhaust gas to flow through when you fit a RR can't help EGT's much, although better than the massive solid block type restriction that the stock cat is. Cheers, Brian. Quote Link to comment Share on other sites More sharing options...
Ady Posted December 7, 2007 Author Share Posted December 7, 2007 If the boost is similar, maybe a few bhp of a difference IMO - no biggy. People don't tend to go for sports cats because of the expense associated with them. TBH I can't see EGT's being much different than with a RR fitted - that tiny hole you introduce for the exhaust gas to flow through when you fit a RR can't help EGT's much, although better than the massive solid block type restriction that the stock cat is. Cheers, Brian. A sport cat seems the perfect answer to me as i can ditch the stock cats, and also not have to worry about MOT times. I know there once overy 12 months , but i just cba with the hassle of getting a cat put in / taken out. Im going to look into the prices of these now. Have seen some supra specific ones for about £400 but going back to have a chat with the lad who dose the exhausts. Cheers for your advice people Quote Link to comment Share on other sites More sharing options...
R Black Posted December 7, 2007 Share Posted December 7, 2007 Let us know how you get on prices and such, goodluck Quote Link to comment Share on other sites More sharing options...
Gaz6002 Posted December 7, 2007 Share Posted December 7, 2007 I wonder if there is a cat available to flow enough for a small single? Quote Link to comment Share on other sites More sharing options...
Ady Posted December 7, 2007 Author Share Posted December 7, 2007 Let us know how you get on prices and such, goodluck Will do mate - wont be happening untill feb/march while im in amsterdam (cars having the work while im away) So ill update this thread Quote Link to comment Share on other sites More sharing options...
Nic Posted December 7, 2007 Share Posted December 7, 2007 I can supply the Weds Revcatalyzer for £369 including postage http://www.weds.co.jp/images/products/gt/catalyzer_pic_03.jpg Quote Link to comment Share on other sites More sharing options...
Pete Posted December 7, 2007 Share Posted December 7, 2007 That's the cheapest sports cat I've seen. Quote Link to comment Share on other sites More sharing options...
Ady Posted December 7, 2007 Author Share Posted December 7, 2007 I can supply the Weds Revcatalyzer for £369 including postage http://www.weds.co.jp/images/products/gt/catalyzer_pic_03.jpg Have you got any more technical info on this nic? is the prics INC vat? looks the part i have to say Quote Link to comment Share on other sites More sharing options...
Nic Posted December 7, 2007 Share Posted December 7, 2007 Only a dodgy Japanese translation HERE Quote Link to comment Share on other sites More sharing options...
tDR Posted December 7, 2007 Share Posted December 7, 2007 I don't understand the squiggles on the Weds site but they do show some images with nearly 20bhp gains. So without reading into that too much (dont know if the boost level went up etc) it would suggest it's a nice and free flowing sportscat, probably ideal for the job. Cheers, Brian. Quote Link to comment Share on other sites More sharing options...
Ady Posted December 7, 2007 Author Share Posted December 7, 2007 Nice one nick - thanks for that. Quote Link to comment Share on other sites More sharing options...
Darren Posted December 9, 2007 Share Posted December 9, 2007 Good thread I think we are all going to have to fit sports CATs at some time in the near future... :( Quote Link to comment Share on other sites More sharing options...
Glosphil Posted December 9, 2007 Share Posted December 9, 2007 Guys, dunno if this helps, but when I had my first cat in, without a RR, the car boosted to over 1.3 bar sometimes. Now with a 1.2 RR in, its always steady at 1.2bar, even in the cold. Therefore I guess putting a high flow cat in, wont negate the need for a RR. Quote Link to comment Share on other sites More sharing options...
Daston Posted December 9, 2007 Share Posted December 9, 2007 I think it also depends on the car. Mine hit 0.9 still with first cat and now bounces of the fuel cut (getting that sorted next month) Quote Link to comment Share on other sites More sharing options...
AndrewOW Posted March 14, 2008 Share Posted March 14, 2008 Ive been speaking to some one who works with custom exhaust builds for years. He spends 24/7 making custom exhausts. Ive been talking about BPU with him and have come up with a diffrent idea to the norm. Rather than going for a double decatt with a 1.2 RR im thinking of decatting the first cat and adding in a top notch sports cat some where where the second cat would be on the stock system and leaving out the restrictor ring. Wont the sports cat provide some back pressure and also act as a restrictor? And I wont have to worry about MOT times as it should also pass the emmisions test. Please no silly replies on ''find a MOT place to overlook the emmisions'' - There is a VOSA van floating arround here now so dont want fines/points for something stupid. Wont it be pointless to put in a RR and a sports cat? Or will the sports cat just get trashed without a RR? Any technical lads out there who can offer some advice on this? Cheers Just doing a search on sport cats and BPU (as I was considering getting one), I found this thread. I wanted to know if you bought one, and how you were getting on with it? Did you ditch the RR, and was there any change in boost pressure or noticeable changes in performance etc? Quote Link to comment Share on other sites More sharing options...
SUPRASUZUKI Posted March 14, 2008 Share Posted March 14, 2008 Iirc a cat is now mandatory to go to the Nring as of January 2008 so if you have planned to go then it may be a wise investment. Is this a definite mate? I'm going in April, so I need to know. Quote Link to comment Share on other sites More sharing options...
TopgunTT Posted March 15, 2008 Share Posted March 15, 2008 Just doing a search on sport cats and BPU (as I was considering getting one), I found this thread. I wanted to know if you bought one, and how you were getting on with it? Did you ditch the RR, and was there any change in boost pressure or noticeable changes in performance etc? Quote Link to comment Share on other sites More sharing options...
garethr Posted March 15, 2008 Share Posted March 15, 2008 Me too I've been wondering about this because my '95 Aristo was given a cat test at the last MOT. I've seen sports catalytic converters for sale on US eBay for silly money -- around 100 dollars delivered (seller b4xs), but do they work? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.