mos Posted April 25, 2003 Share Posted April 25, 2003 Hi all i am wondering if an exhaust on an N/A can be too free flowing i know on a turbo you want as free flowing as possible but isnt back pressure important on an N/A?. Quote Link to comment Share on other sites More sharing options...
Supra_Al Posted April 25, 2003 Share Posted April 25, 2003 Originally posted by mos Hi all i am wondering if an exhaust on an N/A can be too free flowing i know on a turbo you want as free flowing as possible but isnt back pressure important on an N/A?. Interesting...........this is what i have been lead to believe,anyone know? Al. Quote Link to comment Share on other sites More sharing options...
Digsy Posted April 25, 2003 Share Posted April 25, 2003 The exhaust back pressure will play a part in the engine tuning, and theoretically lowering it could have a negative effect, but its difficult to say without trying it. The exhaust pulses will play a part in aiding the evacuation of the exhaust gases from the cylinder, and drawing a fresh charge in. Going to a more free flowing exhaust will also raise the combustion temperatures and lean off the mixture slightly, unless the ECU can learn to compensate. Plenty of stuff in here about retuning after fitting a low backpressure exhaust. Quote Link to comment Share on other sites More sharing options...
eyefi Posted April 25, 2003 Share Posted April 25, 2003 as long as the engine can adjust its fueling to cope with the increased air flow its fine. there r a few owners decatted with performance cat backs on here. Quote Link to comment Share on other sites More sharing options...
eyefi Posted April 25, 2003 Share Posted April 25, 2003 have a look here Quote Link to comment Share on other sites More sharing options...
Syed Shah Posted April 26, 2003 Share Posted April 26, 2003 Yes, it is possible. On the NA, run a TT-designed exhaust and you will end up losing power (except near redline). Anything over 80mm piping is pushing it, and 75mm exhaust piping would probably give the best power gains on an NA (+10-15bhp). Quote Link to comment Share on other sites More sharing options...
Asim Posted May 1, 2003 Share Posted May 1, 2003 Guys as you may or may not know I'm on a really tight budget at the moment and when the rear box came off my 5Zigen exhaust on my 93 NA due to rust (I thought stainless steel didn't rust!?!) I was looking at the cheapest options for repair/replacement. Anyways, I found a garage that said they could fix it and when we put the car on the ramp the exhaust, or what was left of it, from the CAT back was totally rusted except for the resonator bit. So we cut the remaining pipe off, including the rear silencer!!! and then put a new pipe on all the way thru to my rear box, which by the way is definitely SS and sweet!!! and it's all working fine! I was worried about lack of back pressure without the rear silencer but it's all good and a hell of a lot quieter than it was without any rear box at all !!! It's fine at all speeds and only cost me 90 quid. Probably could've got it done cheaper but I've been looking for a garage that could fix it for ages ... Just thought you might be interested ... Quote Link to comment Share on other sites More sharing options...
Supra_Al Posted May 1, 2003 Share Posted May 1, 2003 Hi Asim, i too have an N/A, is your car de-catted as i've heard it makes around 10-15 bhp increase?? Al. Quote Link to comment Share on other sites More sharing options...
Rich J Posted May 1, 2003 Share Posted May 1, 2003 Originally posted by mos Hi all i am wondering if an exhaust on an N/A can be too free flowing i know on a turbo you want as free flowing as possible but isnt back pressure important on an N/A?. What size exhaust are you thinking of getting? I'm running a 2.5" on an 1.8 works well. Design of the exhaust manifold is probably more important than any backpressure the exhaust system is producing. Quote Link to comment Share on other sites More sharing options...
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