Taking manifolds off - does the engine need to come out?
Discussion
m4tti said:
Chris it's a shame your so far away. The Clive F hi flow decats are awesome. The engine feels immediately more responsive and you don't notice the noise until you give it big beans. Cruising no problemo. Look the dogs too.
Hmm, I feel I may have to buy a set of Clive's cats, I have never decatted any of my cars, and hearing other TVR's with de-cat pipes kind of put me off. I know some owners actually drive along with ear protectors, not my idea of fun.But I assume de cat pipes are not equal when it comes to the racket they make, from what you say, and they can boost performance a little more?
Both mine are pussy free with hi flow pipes. The Tuscan has straight through exhaust, I cut the boxes out and welded straight pipe in there but didn't sleeve the cans, the Sag has a carefully modified box and again no sleeves. Like a previous post states, it is OK with out cats, like still acceptable, until you give it some beans.
Exhaust valve timing plays a part in the noise as does the map/chip you use, the Tuscan exhaust is timed between standard and RR but with a long duration and is a deeper sound than others I have heard until it gets going when it gets loud. The Sag has a really sharp sound over 3K, it is distinctive, so much that when I pull the engine out I will record very carefully the timing as I don't want to change the sound although I guess not everyone will like it. In the Sag have had positives from a Diablo owner and passenger whilst on the M25 so that's loud enough I guess. The Tuscan is deeper and generally louder all round with less definition, probably better sounding on idle.
There, that's confused matters....
J
Exhaust valve timing plays a part in the noise as does the map/chip you use, the Tuscan exhaust is timed between standard and RR but with a long duration and is a deeper sound than others I have heard until it gets going when it gets loud. The Sag has a really sharp sound over 3K, it is distinctive, so much that when I pull the engine out I will record very carefully the timing as I don't want to change the sound although I guess not everyone will like it. In the Sag have had positives from a Diablo owner and passenger whilst on the M25 so that's loud enough I guess. The Tuscan is deeper and generally louder all round with less definition, probably better sounding on idle.
There, that's confused matters....
J
Chris, I love the decats. I've no idea what anyone else considers noisy, but I'll happily drive three hours with the roof off, at motorway speeds, and listen to the stereo.
I've a JP rear box and equal length manifolds. That set up gives 118dB on my Maplin meter. The standard back box takes it to 106.
They also make a difference to how the car drives. In a very positive way.
I'm happy to record them, but that won't be representative. If you're coming to Millbrook you can see and hear for yourself.
Oh, they seem to vastly reduce heat soak into the cabin too.
I've a JP rear box and equal length manifolds. That set up gives 118dB on my Maplin meter. The standard back box takes it to 106.
They also make a difference to how the car drives. In a very positive way.
I'm happy to record them, but that won't be representative. If you're coming to Millbrook you can see and hear for yourself.
Oh, they seem to vastly reduce heat soak into the cabin too.
On the original topic . this may help:
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Good luck if you decide to do it in situ .
have fun
Matt
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Good luck if you decide to do it in situ .
have fun
Matt
T40ORA said:
Chris, I love the decats. I've no idea what anyone else considers noisy, but I'll happily drive three hours with the roof off, at motorway speeds, and listen to the stereo.
I've a JP rear box and equal length manifolds. That set up gives 118dB on my Maplin meter. The standard back box takes it to 106.
They also make a difference to how the car drives. In a very positive way.
I'm happy to record them, but that won't be representative. If you're coming to Millbrook you can see and hear for yourself.
Oh, they seem to vastly reduce heat soak into the cabin too.
i must admit my datsun 240z made 116db at 3000rpm and driving back from rotterdam made my ears ring but of course that will go away once the years start to pass by I've a JP rear box and equal length manifolds. That set up gives 118dB on my Maplin meter. The standard back box takes it to 106.
They also make a difference to how the car drives. In a very positive way.
I'm happy to record them, but that won't be representative. If you're coming to Millbrook you can see and hear for yourself.
Oh, they seem to vastly reduce heat soak into the cabin too.
I gave in and ordered a pair of decat pipes from Clive F.
For now, I will have the cats changed at David Geralds, and at the same time, while the exhaust is exposed, I shall wrap the rest of it, including the decat pipes. (hoping to eliminate as much as possible any vibrations and resonance caused by the full bog bore system)
I am resigned to the fact that I can do nothing with the manifolds without spending thousands, so that's not an option for now.
I have bought some DEI Floor & Tunnel Shield II, and will attempt to rip off the old heat shield next to the manifolds and replace it with the new stuff, so it is no longer touching the manifold pipes..
I think I shall book a remap and dyno session after this with Dom, as the exhaust system will be as good as I can get it for now...
For now, I will have the cats changed at David Geralds, and at the same time, while the exhaust is exposed, I shall wrap the rest of it, including the decat pipes. (hoping to eliminate as much as possible any vibrations and resonance caused by the full bog bore system)
I am resigned to the fact that I can do nothing with the manifolds without spending thousands, so that's not an option for now.
I have bought some DEI Floor & Tunnel Shield II, and will attempt to rip off the old heat shield next to the manifolds and replace it with the new stuff, so it is no longer touching the manifold pipes..
I think I shall book a remap and dyno session after this with Dom, as the exhaust system will be as good as I can get it for now...
Edited by chris watton on Sunday 12th July 11:58
OK, on Sunday, I took off the old heat shield near the manifolds and replaced it with some new, thinner material. The fiberglass from the old shield wasn't too good, and looked to be twice the thickness as it should have been. Took quite a while to clean the surface of the bullhead, though..
The manifold pipes no longer touch, but still pretty close!
The manifold pipes no longer touch, but still pretty close!
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