What did you do in the garage yesterday?
Discussion
phazed said:
Graham. Changed the exhaust system yesterday for your spare to see if the resonance is any different from mine.
Wow, yours must be sleeved! Mucho noise, tugs at idle and serious general noise.
Droning at 2K revs very similar.
I always thought that was a quiet one! has it got the scars from being opened? Wow, yours must be sleeved! Mucho noise, tugs at idle and serious general noise.
Droning at 2K revs very similar.
TV8 said:
phazed said:
Graham. Changed the exhaust system yesterday for your spare to see if the resonance is any different from mine.
Wow, yours must be sleeved! Mucho noise, tugs at idle and serious general noise.
Droning at 2K revs very similar.
I always thought that was a quiet one! has it got the scars from being opened? Wow, yours must be sleeved! Mucho noise, tugs at idle and serious general noise.
Droning at 2K revs very similar.
SILICONEKID345HP said:
If I fit these all the droning and resonance has gone.
Do you have a pair of these then. I was at the Kitcar show earlier and found a custom exhaust manufacturer who said they make inserts for tail pipes.
Based in Nuneaton so I'm going to put my sleeved pipe on the car and try them.
If your running Catless or just a big power engine that boom is the box and there's nothing you can do. Sleeved it's totally gone so if I can control the noise with inserts,,, it's worth a try anyway.
roseytvr said:
Al, I have a set of those if you want to try them at shakey next week, and yes a huge power killer, took 20 BNP off mine on the RR.
Hi Ian hope your well mate. If your coming to Shakey that would be great, thanks mate. 20 hp, kin ell I should just leave the cat in there then
The noise thing is about road and cruise driving for me.
I've had a really fast mate have two incidents on trackdays recently and I've decided im not likely to do many in my Tvr now.
I'm slowly making it a very nice road car so all this noise and performance isn't at the top of my list,,, it never really was.
I'm looking for a 10 db reduction at least or my hearing can't cope. Pardon, what was that!
If I can get that reduction using inserts that might allow me to use the sleeved exhaust as I prefer the sound overall.
I wish I'd left pre catts in place because I'm agreeing with Graham
, that's where the noise is produced and makes the booming even with a Cat Y in place much worse.
Straight through manifolds as in the early pre cat cars I think would be much better at resolving some of the boom.
And I could have got a pair awhile ago but didn't go for it
Edited by ClassicChimaera on Monday 1st May 07:53
Vague memories of schoolboy Physics from almost 50 years ago tells me that this could be a harmonic resonance caused by a specific frequency (2000 rpm) being the natural harmonic frequency of some part of the exhaust - the standing wave created is much larger than the normal resonance.
This could be total male round objects, and I could have got some of the terminology wrong, but you may know what I am trying to say. And I certainly don't know how to fix it.
This could be total male round objects, and I could have got some of the terminology wrong, but you may know what I am trying to say. And I certainly don't know how to fix it.
fausTVR said:
If some of the booming is from the front end, I wonder if wrapping the pipes is the answer? If not, has wrapping the silencer been tried?
Wrapping does help, but for me it's the box that causes most of the boom,, I've been considering opening a standard box, renewing or stuffing even more wadding in and welding up again. Not sure wrapping it on the outside would achieve much, something to deaden those vibrations might be a good idea though, strips or something to stop the tin vibrating, I imagine the gases coming in to the box faster, hits the back wall of the box and causes pressure build up and the boom is the gases trying to get through, it's often at low revs, soon as you gas it, they just rush past and negate that boom.
Cherries sort of do the job but are still loud out the rear, not much baffle, it's about finding two silencers that will take the edge off without causing to much restriction so still fast then welding them in there.
QBee said:
Vague memories of schoolboy Physics from almost 50 years ago tells me that this could be a harmonic resonance caused by a specific frequency (2000 rpm) being the natural harmonic frequency of some part of the exhaust - the standing wave created is much larger than the normal resonance.
This could be total male round objects, and I could have got some of the terminology wrong, but you may know what I am trying to say. And I certainly don't know how to fix it.
To early in the morning for me This could be total male round objects, and I could have got some of the terminology wrong, but you may know what I am trying to say. And I certainly don't know how to fix it.
I once read something about Tvr using a sound engineer or a harmonics expert (a choir) a deep Welsh Male Voice Choir
to get the sound right. Was this the early pre cat cars which I have a suspicion don't suffer as much of this problem. I had that boom since the day I removed pre cats, it was there with a cat Y piece after removing them. It nearly knocked me out after driving to France for far to many hours! Insane!
So just replacing the exhaust and still using catted Y for a sleeved exhaust totally removed that deep boom at lower revs as it was now behind and out the tail pipes so if I can use a sleeved exhaust with inserts it might do the job of noise control using a de cat pipe. De cat is loud so sleeved too would be far to loud on a daily basis.
I'm trying to stay de Catt bit have to control firstly boom then overall noise out the rear.
Since going de cat and standard exhaust all my neighbours agree it's quieter but inside the car it's louder. I want the sleeved exhaust on if I can.
I'm thinking,, wider tail pipes and inserts on a sleeved exhaust might be the way to go. It's cheap as chips to have bits bent and welded on so worth some experiment to get it right.
Wider tailpipes the theory being the gases can be muffled there without to much restriction so holding on to the power.
I had a purpose built stainless exhaust fitted to my old XJ 8 Jag ( sports ) and it removed the rear back boxes and even though it had huge middle boxes as normal it boomed in exactly the same way as we are talking about here, Jags being Jags it was only slight but basically the same problem. Silencing is the only way to remove it it seems to me
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