Sports Exhaust + 4L Chim = Loss of torque?
Discussion
Folks,
Having just read a couple of the threads on here tonight (the sports Exhaust one and the 4L underpowered one) got me a thinkin'.....
Last year I had the good people at Thames Valley Racetech do the welding torch honours on my exhaust. Whilst there is no doubting it now sounds fanbloodytastic (the main aim) I have always had the sneaking suspicion the car has not been so quick from the moment I drove it off the forecourt. I could be imagining it but I don't think so, the "sports" exhaust conversion has slowed my 4.0L Chim down! When I last had her serviced Mr Batty said he would do me a deal and swap a factory exhaust back on so he could experiment with my "sports" exhaust, and I jolly nearly took him up on it, infact I still may do so if the offer is still open.
Anyway to my questions:-
1. Is it a generally accepted fact that a hacked about exhaust conversion in this way can lose you acceleration? Is it doing harm to my engine? Can it be easily reversed?
2. What is it about the "David Batty flavour of sports exhaust conversions" that LucyB mentions in her thread that makes it different to my Thames Valley cut'n'shut job.
3. What should I do about it? I too am left thinking my Chim is much slower than it should be - should I get the standard exhaust back and go and get a rolling road tune-up, just the latter, or just live with it?
>>> Edited by arandle on Thursday 13th March 22:23
Having just read a couple of the threads on here tonight (the sports Exhaust one and the 4L underpowered one) got me a thinkin'.....
Last year I had the good people at Thames Valley Racetech do the welding torch honours on my exhaust. Whilst there is no doubting it now sounds fanbloodytastic (the main aim) I have always had the sneaking suspicion the car has not been so quick from the moment I drove it off the forecourt. I could be imagining it but I don't think so, the "sports" exhaust conversion has slowed my 4.0L Chim down! When I last had her serviced Mr Batty said he would do me a deal and swap a factory exhaust back on so he could experiment with my "sports" exhaust, and I jolly nearly took him up on it, infact I still may do so if the offer is still open.
Anyway to my questions:-
1. Is it a generally accepted fact that a hacked about exhaust conversion in this way can lose you acceleration? Is it doing harm to my engine? Can it be easily reversed?
2. What is it about the "David Batty flavour of sports exhaust conversions" that LucyB mentions in her thread that makes it different to my Thames Valley cut'n'shut job.
3. What should I do about it? I too am left thinking my Chim is much slower than it should be - should I get the standard exhaust back and go and get a rolling road tune-up, just the latter, or just live with it?
>>> Edited by arandle on Thursday 13th March 22:23
Folks,
Having just read a couple of the threads on here tonight (the sports Exhaust one and the 4L underpowered one) got me a thinkin'.....
Last year I had the good people at Thames Valley Racetech do the welding torch honours on my exhaust. Whilst there is no doubting it now sounds fanbloodytastic (the main aim) I have always had the sneaking suspicion the car has not been so quick from the moment I drove it off the forecourt. I could be imagining it but I don't think so, the "sports" exhaust conversion has slowed my 4.0L Chim down! When I last had her serviced Mr Batty said he would do me a deal and swap a factory exhaust back on so he could experiment with my "sports" exhaust, and I jolly nearly took him up on it, infact I still may do so if the offer is still open.
Anyway to my questions:-
1. Is it a generally accepted fact that a hacked about exhaust conversion in this way can lose you acceleration? Is it doing harm to my engine? Can it be easily reversed?
2. What is it about the "David Batty flavour of sports exhaust conversions" that LucyB mentions in her thread that makes it different to my Thames Valley cut'n'shut job.
3. What should I do about it? I too am left thinking my Chim is much slower than it should be - should I get the standard exhaust back and go and get a rolling road tune-up, just the latter, or just live with it?
>>> Edited by arandle on Thursday 13th March 22:23
To answer your questions: yes you do lose torque and a minimal amount of bhp due to the loss of back pressure.This was my experience. It can be reversed by simply replacing the perforated tubes and the baffle. To compensate this loss the simplest is to add an induction system (see ACT) which balances the inlet and exit ports to a certain degree (V8's generally have small inlet relative to exhaust ports). This requires a reprogrammed ECU which can be obtained ready burned in from Mark Adams (best guess). Total cost at least £800. Alternatively "tune" the exhaust by reducing the diameter of the straight through tubes to increase back pressure.
You could put the car on the rolling road at Power Engineering Uxbridge, they have many 4.0L power graphs stored on their system and could do a conparison graph, the 4.0L are quite consistant.( they charge £75 per hour & would take 30 mins)
This has been mentioned before, although does depend on how the modification is done, if larger diameter pipe is fitted it will reduce back pressure and possibly affect output, although cars that turn up for dyno sessions with "sports" mod don't normally show any noticable power loss.
I have to say that i would leave silencing as standard, maybe i'm getting old?
This has been mentioned before, although does depend on how the modification is done, if larger diameter pipe is fitted it will reduce back pressure and possibly affect output, although cars that turn up for dyno sessions with "sports" mod don't normally show any noticable power loss.
I have to say that i would leave silencing as standard, maybe i'm getting old?
Thanks Magnus and 2 sheds - I think I will get on up to Uxbridge and get the car given the once over and see how she compares with what they know to be true. I certainly don't fancy paying another £800 to get the car back where she was before the "mod"!
....I too am coming to the opinion that I should have left well alone (mid thirties setting)....
....I too am coming to the opinion that I should have left well alone (mid thirties setting)....
Hmmm - can you e-mail me your telephone number 2 sheds (+ name!!) to AndyRandle@Easynet.co.uk - as it happens the Tivs in for it's MOT next Wednesday Morning but I would like to pay you a visit in the afternoon if that's a goer?
Drop me a note and I'll give you a call to arrange??
Cheers,
- A.
Drop me a note and I'll give you a call to arrange??
Cheers,
- A.
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