Does anyone know anything about exhaust silencer design?
Discussion
I have a noisy TVR Griffith, and I want to make it quieter. Right now, it's absurdly noisy and there isn't a track in the UK which would let me near it. This is spoiling ownership somewhat.
The car has a fairly wild cam and a "few" other mods, but the exhaust is standard TVR.
I've tried re-packing the silencer and that hasn't made much difference, so where would be a good place to look next? Ideally, I'd like to reduce the current level of 114dB to around 100db.
The car has a fairly wild cam and a "few" other mods, but the exhaust is standard TVR.
I've tried re-packing the silencer and that hasn't made much difference, so where would be a good place to look next? Ideally, I'd like to reduce the current level of 114dB to around 100db.
Obvious one I guess is to add more silencers in.
I got pissed off with mine recently. I used to have only 2 3" magnaflow silencers and its fairly loud.....and droney at 70mph which was the worst bit.
I bought 2 4"OD Moros0 Spiral flow silencers from Summit at $100ea.
Space is very tight, and its as much as I could squeeze in. They defo helped....not sure how much though in terms of db.
Cheap, stainless, and no materials to wear out. They force most of the exhaust gases in a spiral flow pattern, both with s small diam hole in the middle for straight through too.
They arent supposed to be restrictive.
I tried to price some custoim made stuff here in the UK, and prices were just mental.
Check Summit and Magnaflow etc to see what they list.
I got pissed off with mine recently. I used to have only 2 3" magnaflow silencers and its fairly loud.....and droney at 70mph which was the worst bit.
I bought 2 4"OD Moros0 Spiral flow silencers from Summit at $100ea.
Space is very tight, and its as much as I could squeeze in. They defo helped....not sure how much though in terms of db.
Cheap, stainless, and no materials to wear out. They force most of the exhaust gases in a spiral flow pattern, both with s small diam hole in the middle for straight through too.
They arent supposed to be restrictive.
I tried to price some custoim made stuff here in the UK, and prices were just mental.
Check Summit and Magnaflow etc to see what they list.
The best way to shut things up is to add more volume to the silencer box or extra silencers, if you add more baffles then this obviously reduces the exhaust flow and the engine power.
You could probably squeeze a couple of cherry bomb type silencers in after the main box, these would probably knock a couple of dB off.
Otherwise its take the main box apart to fit some baffles.
Matt
You could probably squeeze a couple of cherry bomb type silencers in after the main box, these would probably knock a couple of dB off.
Otherwise its take the main box apart to fit some baffles.
Matt
Check Summit...they have loads of them, and not that expensive. But agreed, the types with chambers etc would be better. The bigger the better, as it will help both flow, and silencing.
Having driven with my SpiralFlow Moroso's for a few more days....the noise reduction is actually quite a lot. Probably not enough for you tho, to be safe.
But I did buy the smallest ones available, due to the space I had to fit them.
Having driven with my SpiralFlow Moroso's for a few more days....the noise reduction is actually quite a lot. Probably not enough for you tho, to be safe.
But I did buy the smallest ones available, due to the space I had to fit them.
1) get a pair of super-trapp silencers, you can add or remove plates to create more back pressure and reduce noise......
2) or....buy a pair of decibel inserts from Jetex, I have used these myself to avoid the sound trap at donnington and it worked a treat, I know others that have used them to great effec too, and they do not create a noticable decrease in performance or lap times.....it sounds like you have a pair of straight-through race silencers? otherwise known as "absorbtion" silencers......these will work well with the decibel inserts as your wadding pretty much isnt doing anything at the mo, the decibel insert will force the gas more into the wadding......the decibel inserts are dirt cheap, about a tenner each, the super traps are about a ton each.......obviously try the cheap option first......so get on to Jetex!
forget cherry bombs, they are utter shite
2) or....buy a pair of decibel inserts from Jetex, I have used these myself to avoid the sound trap at donnington and it worked a treat, I know others that have used them to great effec too, and they do not create a noticable decrease in performance or lap times.....it sounds like you have a pair of straight-through race silencers? otherwise known as "absorbtion" silencers......these will work well with the decibel inserts as your wadding pretty much isnt doing anything at the mo, the decibel insert will force the gas more into the wadding......the decibel inserts are dirt cheap, about a tenner each, the super traps are about a ton each.......obviously try the cheap option first......so get on to Jetex!
forget cherry bombs, they are utter shite
Edited by knighty on Tuesday 8th January 15:56
Edited by knighty on Tuesday 8th January 15:56
rev-erend said:
It may have been modified - run your hand along the top[ of the silender and feel for a weld mark from front to back..
or the insides may well just be shot thru age.
It's not been altered by anyone except me when I repacked the silencer last year. It made not the slightest difference or the insides may well just be shot thru age.
Hi dnb,
I design and build exhausts. exchaust noise is a daily issue with us and its difficult to get right. the best design is a silencer with a direct path, it will silence the exhaust but not be too restrictive, during dyno testing on a 180bhp n/a engine we saw a drop of 12 bhp with a non-direct type silencer but a big noise reduction at the same time.
the battle is to slow down gas speed without compromising gas flow. (gas speed and flow are very different) if you can find the point at which slowing the gasses down enough to get to a comfortable noise level without sacrificing power you have cracked it, but that is never easy, or cheap.
if you can get under the car and take some pics of the current system I will be happy to try and give some advice and supply silencers if needed as we can make them up to any size and spec, we have got masses of experience and files full of info on previous cars, inc TVR's.
Dave
Vsport.
I design and build exhausts. exchaust noise is a daily issue with us and its difficult to get right. the best design is a silencer with a direct path, it will silence the exhaust but not be too restrictive, during dyno testing on a 180bhp n/a engine we saw a drop of 12 bhp with a non-direct type silencer but a big noise reduction at the same time.
the battle is to slow down gas speed without compromising gas flow. (gas speed and flow are very different) if you can find the point at which slowing the gasses down enough to get to a comfortable noise level without sacrificing power you have cracked it, but that is never easy, or cheap.
if you can get under the car and take some pics of the current system I will be happy to try and give some advice and supply silencers if needed as we can make them up to any size and spec, we have got masses of experience and files full of info on previous cars, inc TVR's.
Dave
Vsport.
dave.a said:
Hi dnb,
I design and build exhausts. exchaust noise is a daily issue with us and its difficult to get right. the best design is a silencer with a direct path, it will silence the exhaust but not be too restrictive, during dyno testing on a 180bhp n/a engine we saw a drop of 12 bhp with a non-direct type silencer but a big noise reduction at the same time.
the battle is to slow down gas speed without compromising gas flow. (gas speed and flow are very different) if you can find the point at which slowing the gasses down enough to get to a comfortable noise level without sacrificing power you have cracked it, but that is never easy, or cheap.
if you can get under the car and take some pics of the current system I will be happy to try and give some advice and supply silencers if needed as we can make them up to any size and spec, we have got masses of experience and files full of info on previous cars, inc TVR's.
Dave
Vsport.
As with all sports cars - the big problem is ground clearance and actual space for the silencer..I design and build exhausts. exchaust noise is a daily issue with us and its difficult to get right. the best design is a silencer with a direct path, it will silence the exhaust but not be too restrictive, during dyno testing on a 180bhp n/a engine we saw a drop of 12 bhp with a non-direct type silencer but a big noise reduction at the same time.
the battle is to slow down gas speed without compromising gas flow. (gas speed and flow are very different) if you can find the point at which slowing the gasses down enough to get to a comfortable noise level without sacrificing power you have cracked it, but that is never easy, or cheap.
if you can get under the car and take some pics of the current system I will be happy to try and give some advice and supply silencers if needed as we can make them up to any size and spec, we have got masses of experience and files full of info on previous cars, inc TVR's.
Dave
Vsport.
As you say - a picture is really needed..
An absorption type silencer is good for flow but bad at silencing individual bangs in the exhaust .. for this reason they work much better if you have either some sort of expansion chamber upstream or you fit the absorption silencer at the rear of the car where the flow has smoothed out.
350Matt said:
The best way to shut things up is to add more volume to the silencer box or extra silencers, if you add more baffles then this obviously reduces the exhaust flow and the engine power.
You could probably squeeze a couple of cherry bomb type silencers in after the main box, these would probably knock a couple of dB off.
Otherwise its take the main box apart to fit some baffles.
Matt
I think the cherry bombs after the main silencer sounds worth a tryYou could probably squeeze a couple of cherry bomb type silencers in after the main box, these would probably knock a couple of dB off.
Otherwise its take the main box apart to fit some baffles.
Matt
after all your only trying to lose the edge.I'll get some better photos next time I'm under the car... It's not very clear here, other than seeing that there's very little space.
David - I may take you up on the exhaust design & make, although I fear you may be the wrong end of the country for me! I need to get the car on a track!
David - I may take you up on the exhaust design & make, although I fear you may be the wrong end of the country for me! I need to get the car on a track!
Looks like there is no exhaust on it - as I cannot see the tail pipes .. and looking at it and from memory - I'd guess the pipes run inside the chassis rails .. probably the only option being a pair of small cherry bomb style silencers at the rear ..
I'm sure Trackcar would be the best person to provide
the answer.
I'm sure Trackcar would be the best person to provide
the answer.
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