Anti reversal cones - who does 'em?
Discussion
While she's in bits I may as well get a few things sorted. Before I get the headers/y piece ceramic coated I figured having the anti reversal cones fitted might make it sound less of a bag of spanners. Any recommendations for who could do this, and what sort of cost should I expect? Mine are TVR standard cat-less parts.
Anyone with an angle grinder and a welder could do that for you. Tower View did mine a few years ago. The difference is hardly measurable let enough enough to notice, and to be honest it's not something I would bother with unless they already had the exhaust off and working on it for some other reason.
GreenV8S said:
Anyone with an angle grinder and a welder could do that for you. Tower View did mine a few years ago. The difference is hardly measurable let enough enough to notice, and to be honest it's not something I would bother with unless they already had the exhaust off and working on it for some other reason.
Pete, I am going to have my manifolds ceramic coated, would it be worth having pre-cats repaced with cones whilst the're off or wouldn't you bother?
macdeb said:
Pete, I am going to have my manifolds ceramic coated, would it be worth having pre-cats repaced with cones whilst the're off or wouldn't you bother?
Depends how much they're going to cost. If you're happy to spend say £40-50 to gain a couple of lb-ft then there's no harm in it. As I said before, I decided to have mine while they were taking the precats out because it's relatively cheap power albeit not much. But it's your money at the end of the day.
I asked not for any power gains (though they are welcome!), more to improve the quality of sound.
My impression, particularly with the big empty Y piece canister, is that the exhaust gasses expanding in these big empty cylinders causes a racket not unlike noisy tappets or leaking manifolds - a nasty tinny bag of spanners sort of noise. This somewhat detracts from the initial purpose of the decat - which for me again was not about power, more about getting the right TVR noise. It won't be right until it sounds like a 450 SEAC IMHO.
Now I may be wrong about this (particularly as I actually do seem to have had a leaky manifold gasket) and I stand to be corrected, but adding the cones I would presume would smooth out the gas flow and reduce this ringing.
For clarity: I'm talking about precats and cats; a full decat using standard TVR parts, which are visually identical to catted parts from the outside, but have nothing inside them. They are off the car at the moment, and will shortly be going to get ceramic coated as I'm sick of frying components. Obvioulsy once cermamic coated any cut & shut work would be out of the question. I'm sure anyone who could weld could do the job, but I'd prefer someone who is actually experienced in doing the job to do it.
>> Edited by victormeldrew on Monday 5th December 12:50
My impression, particularly with the big empty Y piece canister, is that the exhaust gasses expanding in these big empty cylinders causes a racket not unlike noisy tappets or leaking manifolds - a nasty tinny bag of spanners sort of noise. This somewhat detracts from the initial purpose of the decat - which for me again was not about power, more about getting the right TVR noise. It won't be right until it sounds like a 450 SEAC IMHO.
Now I may be wrong about this (particularly as I actually do seem to have had a leaky manifold gasket) and I stand to be corrected, but adding the cones I would presume would smooth out the gas flow and reduce this ringing.
For clarity: I'm talking about precats and cats; a full decat using standard TVR parts, which are visually identical to catted parts from the outside, but have nothing inside them. They are off the car at the moment, and will shortly be going to get ceramic coated as I'm sick of frying components. Obvioulsy once cermamic coated any cut & shut work would be out of the question. I'm sure anyone who could weld could do the job, but I'd prefer someone who is actually experienced in doing the job to do it.
>> Edited by victormeldrew on Monday 5th December 12:50
victormeldrew said:
adding the cones I would presume would smooth out the gas flow and reduce this ringing.
Not particularly. You're replacing a 4-into-1 collector with an abrupt change in cross section area. Neither of them are particularly good or bad in terms of air flow, the cone is just slightly better at attenuating the reverse pulse as it goes back towards the head. Some people say it makes a small difference to the tone of the exhaust, can't say I noticed in mine to be honest. Lagging the primaries made a much bigger difference, I guess mainly from the physical damping effect and perhaps partly from the higher gas temperatures and speeds. You might find some change just from having the thicker new manifolds and higher gas temperatures from the ceramic coating.
Bottom line I don't think any of the effects are particularly dramatic but it's a cheap mod, so if you're interested there's no reason not to do it. Amongst other things, if you perceive it as a possible benefit it's worth considering just so you don't have to worry six months down the line whether it might have been even better with the cone fitted.
GreenV8S said:
Pete, I am going to have my manifolds ceramic coated, would it be worth having pre-cats repaced with cones whilst the're off or wouldn't you bother?
Depends how much they're going to cost. If you're happy to spend say £40-50 to gain a couple of lb-ft then there's no harm in it. As I said before, I decided to have mine while they were taking the precats out because it's relatively cheap power albeit not much. But it's your money at the end of the day.
Cheers bloke, I'll probably go the whole way, no point wondering 'what if' after.
v8 racing said:Yup, like Quinny says, I am already deficient in cats to the tune of three.
the biggest tone difference come from removing the main cat not the precats although i wouldnt recomend it for mot issues, try and find a second hand one without a cat you can just swap when mot time comes around
Unless you count the three on the top shelf in my garage, there for potential MoT purposes, but strangely never actually having been required for said purpose. Never been a problem.
No, the sound out of the back end is already aural heaven, its just the marble in a tin can noise fron the front I want to sort out. I'm going to ring a few of the usual suspects tomorrow to see if I can get some cones welded in. Then they'll be off for ceramic coating. If they still sound ropey after all that I'll try wrapping 'em as well; at least with the ceramic coating on rust won't be an issue!
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