Factory says 'no' to sports exhaust?
Discussion
IIRC, dB's are measured on a logarithmic scale so for every 10dB the percieved 'loudness' is doubled. 100dB to 110dB is a massive increase and equally, you have to decrease it massively to get the levels down again. I understand that some cars are struggling to meet the tighter regs at some circuits on standard exhausts...
quote:
A straight through pipe will take the exhaust to in excess of 110db possibly higher. Forget about getting anywhere near 98 to 100 db on a track even with inserts. They will bring it down a bit 5-7 db but this is not enough. The inserts are useful when you are borderline but with a straight through pipe the noise levels are very loud indeed and the inserts are limited in what the can bring under control. Noise measurement is a bit hit and miss and the readings can vary by 2-3 db with no problems so ideally you want to be well under.
So what are the conclusions of this debate?
If i removed pre-cats and left rear box standard(griff 500HC) would that release any power/Noise...OR if i did both, remove pre-cats and mod rear exhaust (same engine). Which is better/safer? Thanks, sorry to drag up again, but just wanted a short and sweet definitive'ish answer.....................
If i removed pre-cats and left rear box standard(griff 500HC) would that release any power/Noise...OR if i did both, remove pre-cats and mod rear exhaust (same engine). Which is better/safer? Thanks, sorry to drag up again, but just wanted a short and sweet definitive'ish answer.....................
quote:
So what are the conclusions of this debate?
If i removed pre-cats and left rear box standard(griff 500HC) would that release any power/Noise...OR if i did both, remove pre-cats and mod rear exhaust (same engine). Which is better/safer? Thanks, sorry to drag up again, but just wanted a short and sweet definitive'ish answer.....................
Sorry there is no sweet simple answer. Well there is but most people don't like it which is leave things as they are.
Neither is going to turn your car into a power crazed beast and it may well do the opposite but it is a big unknown. Your responsibility, not mine. Would I do it? No.
This debate has raised the fact that exhaust mods can damage/degrade the car's performance and that it is a bit of a black art making modifications. Making cars noisier makes their use on a track virtually impossible.
In other words there are risks and drawbacks. You need to weigh these up and decide.
If you are modding the engine, then maybe consider removing the pre-cats is worth it but then you will be doing other things to help get more mixture into the engine to give you more power.
If you want more power, there is no cheap way to get it with these engines.
Steve
www.tvrbooks.co.uk
quote:Out of interest my Griff with it's straight through exhaust measured 110db at Goodwood as is, and 100 with "Merlin Mufflers" external silencers. Bedford incidentally let me out toplay without the mufflers
A straight through pipe will take the exhaust to in excess of 110db possibly higher. Forget about getting anywhere near 98 to 100 db on a track even with inserts.
Rich...quote:
quote:Out of interest my Griff with it's straight through exhaust measured 110db at Goodwood as is, and 100 with "Merlin Mufflers" external silencers. Bedford incidentally let me out toplay without the mufflers
A straight through pipe will take the exhaust to in excess of 110db possibly higher. Forget about getting anywhere near 98 to 100 db on a track even with inserts.
Goodwood is 98 which means you can't play and as I said, the readings can vary by 2-3 db. I was at Silverstone this summer in the evenings with a 98 limit so that's out. 3 hours on the GP circuit for £105. Excellent fun but a 100 dB wouldn't make it.
As for Bedford I know people who were prevented from going on track because of noise and didn't get a refund!
Steve
>> Edited by shpub on Wednesday 18th September 18:58
quote:
So what are the conclusions of this debate?
If i removed pre-cats and left rear box standard(griff 500HC) would that release any power/Noise...OR if i did both, remove pre-cats and mod rear exhaust (same engine). Which is better/safer? Thanks, sorry to drag up again, but just wanted a short and sweet definitive'ish answer.....................
Basically by removing the pre-cats ( the ones in each manifold) you will see a small increase in power especially If your Cats are blocked, however if you just "knock them out" without making any adjustments to the ECU you will gain nothing, the other problem is that when you remove these your left with an empty chamber, which although is a cheap solution offering a small benefit its not totally ideal, as the gas gets "out of shape" without the restriction of a cat. you really need longer primary pipes or an internal reducer. If you start to de-cat you will need your main silencer IMHO .
hope this helps ?????
quote:
Turncoat; and you've just bought a Chimaera!!
'well get a Wedge or an S then'
But I wanted something that looks good and handles...
But Chim's are beautiful and wedges are, erm, distinctive. Sorry all Wedge owners - just ribbing ya!
Aint ready for me slippers yet
:exitstagerightwiththesoundofsize10hobnailsshufflingwithmenacemyway:
So being one of those people who learn by trial and error and no other way here are the results of my test.....
Actions taken:-
Removed exhaust system, opened silencer, removed wadding, welded up silencer, fitted exhaust (2 hrs work)
Results:-
Beautiful sound on tick over
Howls like a banshee at high RPM
Pops and bangs on overrun
slower to pick up from low/ mid range RPM
Top gear acceleration slower
Conclusions:-
This is not a good mod unless the sound is more important than the performance
Next steps:-
Re pack silencer
Enjoy sound slightly less
able to piss past anything on road once again
Questions:-
Anybody know where I can get some silencer wadding?
Actions taken:-
Removed exhaust system, opened silencer, removed wadding, welded up silencer, fitted exhaust (2 hrs work)
Results:-
Beautiful sound on tick over
Howls like a banshee at high RPM
Pops and bangs on overrun
slower to pick up from low/ mid range RPM
Top gear acceleration slower
Conclusions:-
This is not a good mod unless the sound is more important than the performance
Next steps:-
Re pack silencer
Enjoy sound slightly less
able to piss past anything on road once again
Questions:-
Anybody know where I can get some silencer wadding?
SimonT
The Empty silencer/ leave perforated isn't the normal method of modification, the perforated tubes are replaced with solid pipe, , in effect zero silencing.
this however is bloody loud !. but won't have the adverse effect on performance. This is why some people opt for a complete new sports systems (with a smaller silencer). i personally think they sound fine with standard systems, but am becoming a bit of "old fart".
Tim
The Empty silencer/ leave perforated isn't the normal method of modification, the perforated tubes are replaced with solid pipe, , in effect zero silencing.
this however is bloody loud !. but won't have the adverse effect on performance. This is why some people opt for a complete new sports systems (with a smaller silencer). i personally think they sound fine with standard systems, but am becoming a bit of "old fart".
Tim
shpub said:
So what are the conclusions of this debate?
If i removed pre-cats and left rear box standard(griff 500HC) would that release any power/Noise...OR if i did both, remove pre-cats and mod rear exhaust (same engine). Which is better/safer? Thanks, sorry to drag up again, but just wanted a short and sweet definitive'ish answer.....................
Sorry there is no sweet simple answer. Well there is but most people don't like it which is leave things as they are.
Neither is going to turn your car into a power crazed beast and it may well do the opposite but it is a big unknown. Your responsibility, not mine. Would I do it? No.
This debate has raised the fact that exhaust mods can damage/degrade the car's performance and that it is a bit of a black art making modifications. Making cars noisier makes their use on a track virtually impossible.
In other words there are risks and drawbacks. You need to weigh these up and decide.
If you are modding the engine, then maybe consider removing the pre-cats is worth it but then you will be doing other things to help get more mixture into the engine to give you more power.
If you want more power, there is no cheap way to get it with these engines.
Steve
www.tvrbooks.co.uk
Hi Steve!
You worry me. I removed all the silencing material from the standard exhaust on my 4L Chim. It now sounds great at low revs but a bit like a garbage truck emptying its load at higher revs. I am an old fart so rarely go above 3000--what worries me is--am I damaging the engine? The power overtaking etc seems much the same apart from the appalling row (which seems to really piss some road users off--I get quite aggressive reactions sometimes--flashing lights etc). Would appreciate your advice.
I did a track day at Goodwood yesterday (Chim 500, standard exhaust). The noise measured *just* over the 98db limit according to the tester, but luckily they allowed me to continue anyway. I was pretty anxious at this point as I had watched 3 other cars turned away (not TVRs). If noise measurements vary by 2-3db anyway, is there a cheap fix if you find you are just over? I have heard that stuffing wire wool down the tail pipes is quite effective - be a bit worried about fishing it all out again afterward though!
alan_d said: I did a track day at Goodwood yesterday (Chim 500, standard exhaust). The noise measured *just* over the 98db limit according to the tester, but luckily they allowed me to continue anyway. I was pretty anxious at this point as I had watched 3 other cars turned away (not TVRs). If noise measurements vary by 2-3db anyway, is there a cheap fix if you find you are just over? I have heard that stuffing wire wool down the tail pipes is quite effective - be a bit worried about fishing it all out again afterward though!
See the noise FAQ on my website. There are solutions like the Tower View Inserts of external silencers (Merlin or ACT).
Steve
www.tvrbooks.co.uk
Sorry to add yet another option to this thread but...
OK, so taking out the baffles reduces back pressure which compromises the way the engine was designed to run and therefore might cause long term problems, though not sure what.
What if one took the other route to more noise and removed all 3 cats, but left the baffles etc untouched? Could this lead to longer term problems, and if so what?
OK, so taking out the baffles reduces back pressure which compromises the way the engine was designed to run and therefore might cause long term problems, though not sure what.
What if one took the other route to more noise and removed all 3 cats, but left the baffles etc untouched? Could this lead to longer term problems, and if so what?
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