Exhaust Noise Again! The facts please
Discussion
Tested my SBC 550hp CanAm today according to trackday specs 0.5m at 45degrees to exhaust. Got a reading on 105.3dba at 4000rpm when limit is 101dba. I have searched hard on this forum for info and there is some there but.
Can any body tell me. What they did? who built it for them? What was the before and after noise reading? How much power was lost? And how much did it cost? Because the Neal nitty Gritty of it is hard to find.
Does the factory option work? They say 98dba but what was the starting figure?
I have recently been reading a book on Small Blocks by David Vizard in which he says it is possible to build a system which does the job without sacrificing more than 1% power! I believe it is referred to elsewhere on this forum.
I don't want to drive for 120 odd miles to Bedford to be told to go home either at the gate or after my first lap as a few did when I was there on Saturday what an anticlimax and waste of money.
I would like to do a proper job and sort it once and for all.
Can any body tell me. What they did? who built it for them? What was the before and after noise reading? How much power was lost? And how much did it cost? Because the Neal nitty Gritty of it is hard to find.
Does the factory option work? They say 98dba but what was the starting figure?
I have recently been reading a book on Small Blocks by David Vizard in which he says it is possible to build a system which does the job without sacrificing more than 1% power! I believe it is referred to elsewhere on this forum.
I don't want to drive for 120 odd miles to Bedford to be told to go home either at the gate or after my first lap as a few did when I was there on Saturday what an anticlimax and waste of money.
I would like to do a proper job and sort it once and for all.
Edited by MarkWebb on Sunday 7th February 21:43
The secret for not loosing power is to find silencers that will flow the amount of cfm that the car produces at max power...
The biggest problem with the ultima is the total length of the exhaust and the heat generated in the silencer melts/burns the wadding..
Most repack the standard silencers, but my headers are long, so the silencer bolts straight onto it and gets loud quick.......A X pipe might help..or another small inline silencer on each side as well.
Flowmaster silencers will flow the cfm, but whether they are quite enough i dont know..... your lucky im 115 db at the moment!!!!!!!!
im looking at a 'y' piece directly after the headers and then having 4 silencers next to each other, in theory 2 cylinders gases will go to each silencer and hense be quieter and less restrictive...
Dom
The biggest problem with the ultima is the total length of the exhaust and the heat generated in the silencer melts/burns the wadding..
Most repack the standard silencers, but my headers are long, so the silencer bolts straight onto it and gets loud quick.......A X pipe might help..or another small inline silencer on each side as well.
Flowmaster silencers will flow the cfm, but whether they are quite enough i dont know..... your lucky im 115 db at the moment!!!!!!!!
im looking at a 'y' piece directly after the headers and then having 4 silencers next to each other, in theory 2 cylinders gases will go to each silencer and hense be quieter and less restrictive...
Dom
Bedford is always going to be a tough call. Can I suggest Goodwood at 105db, Silverstone 105 etc.
Repacking the standard boxes works OK but the packing has only a very short life. Tried a variety of materials - all useless. I am presently looking into a permanent solution and will be doing some interesting experiments shortly. The experience of my exhaust man is that a proper X pipe is worth 3db, but clearly a genuine X pipe is almost impossible to package in an Ultima.
Kyles 4 silencer looks a good idea.
Repacking the standard boxes works OK but the packing has only a very short life. Tried a variety of materials - all useless. I am presently looking into a permanent solution and will be doing some interesting experiments shortly. The experience of my exhaust man is that a proper X pipe is worth 3db, but clearly a genuine X pipe is almost impossible to package in an Ultima.
Kyles 4 silencer looks a good idea.
Very simple solution which often helps, just for those tracks which have limited sound levels, which looks like s
t, is fitting a 90 degree bend on the muffler exit. point it down and you will gain (or loose depends ho you look at it) a few Db.
I had it once, and went to a DIY shop and bought a heaterexhaustbend and fixed it with a hoseclamp. (two in case of the ultima)
Another solution is making a tube with holes which you can fix into the endpipe. You will loose some power, but it's better driving with less power, then being blackflagged due to noise.
t, is fitting a 90 degree bend on the muffler exit. point it down and you will gain (or loose depends ho you look at it) a few Db. I had it once, and went to a DIY shop and bought a heaterexhaustbend and fixed it with a hoseclamp. (two in case of the ultima)
Another solution is making a tube with holes which you can fix into the endpipe. You will loose some power, but it's better driving with less power, then being blackflagged due to noise.
Edited by harry b on Monday 8th February 14:14
Edited by harry b on Monday 8th February 14:15
Thanks Harry.
I am really after a proper solution which works all the time and doesn't involve repacking silencers every trackday and also looks the part.
I have a feeling that it won't be cheap but there is nothing worse than getting syked up for a trackday and then getting tuned away before it even starts!
I am really after a proper solution which works all the time and doesn't involve repacking silencers every trackday and also looks the part.
I have a feeling that it won't be cheap but there is nothing worse than getting syked up for a trackday and then getting tuned away before it even starts!
Mark,
I have the same concerns as you but see my solution I referred to in a previous post:
I have the same concerns as you but see my solution I referred to in a previous post:
robm3 said:
As for silencers and mufflers I'm going to run Supertrapp discs to keep the noise down when needed. These are pretty popular in Australia but don't seem to be so here in the UK. They're actually a great idea as you can add/remove plates to adjust your volume. I kept the pipes open ended so I can screw the supertrapps onto them.
Nothing worse than turning up at a trackday only to find you're blackflagged due to noise right...
www.supertrapp.com/product_sections/cat.asp?CatID=...
www.demon-tweeks.co.uk/products/ProductDetail.asp?...
Nothing worse than turning up at a trackday only to find you're blackflagged due to noise right...
www.supertrapp.com/product_sections/cat.asp?CatID=...
www.demon-tweeks.co.uk/products/ProductDetail.asp?...
Rob
I have read your previous and looked into supertrap. However I am not happy bolting them onto the back of my car for all to see and I have read some horrendous stories of power loss depending on what you have to set them at to get the noise down.
I would of course be keen to hear how you get on.
I have read your previous and looked into supertrap. However I am not happy bolting them onto the back of my car for all to see and I have read some horrendous stories of power loss depending on what you have to set them at to get the noise down.
I would of course be keen to hear how you get on.
Edited by MarkWebb on Tuesday 9th February 12:49
my car was 526bhp on AS dyno and measured 108db with the std system... I got it down to 101db by fitting new straight through silencers and adding extra length by turnng back towards the engine after the silencers then back around and into a balance box above the gearbox & out of car in original place.
The end result was an exhaust which was more free flowing and yet nearly 8db quieter (due to the balance box and extra length... oh and it being straight through allowed for huge flames from the exhaust lol.... I easily got onto bedford with this setup.
sorry edited to add that we tested it officially at goodwood at 108db and then again when we made the exhaust for before and after direct comparison... all done in same location on same day...
At bedford it was meansured as 100.5db (and thus I went on track) and clives was next to mine and they also measured his at over 108db.... all tested at over 5000rpm as my engine rev'd to 7000rpm.
The end result was an exhaust which was more free flowing and yet nearly 8db quieter (due to the balance box and extra length... oh and it being straight through allowed for huge flames from the exhaust lol.... I easily got onto bedford with this setup.
sorry edited to add that we tested it officially at goodwood at 108db and then again when we made the exhaust for before and after direct comparison... all done in same location on same day...
At bedford it was meansured as 100.5db (and thus I went on track) and clives was next to mine and they also measured his at over 108db.... all tested at over 5000rpm as my engine rev'd to 7000rpm.
Edited by andygtt on Tuesday 9th February 13:57
MarkWebb said:
Rob
I have read your previous and looked into supertrap. However I am not happy bolting them onto the back of my car for all to see and I have read some horrendous stories of power loss depending on what you have to set them at to get the noise down.
I would of course be keen to hear how you get on.
Absolutely agree, it does seem a well set up muffler can beat what I'm going to do. I intend to run without the Supertrapps but only fit them when and where needed.I have read your previous and looked into supertrap. However I am not happy bolting them onto the back of my car for all to see and I have read some horrendous stories of power loss depending on what you have to set them at to get the noise down.
I would of course be keen to hear how you get on.
Edited by MarkWebb on Tuesday 9th February 12:49
It's just I'd hate to get banned at a trackday, it's happened once to me before in a Lotus sport 160(Oulton Park) and I was gutted.
I'm sure powerloss will occur but hey, I got plenty to give away anyhow (even do trackdays with the A/C on in summer)
Here's some discussions on the supertrapps:
http://grassrootsmotorsports.com/project-cars/1992...
http://sccaforums.com/forums/thread/283518.aspx
It was bespoke made by custome chrome for around £750, unfortunatelly I cant find the pics at the min.
The silencers were straight through but had a special perforation inside that helped capture the gasses rather than have a z trap like the ultima ones.... unfortunatelly like the Ultima ones the silencers need repacking regularly as they are so close to the headers it blows and burns the wadding out.
Must admit Id use different silencers if I was to do it again... I just had some made for my noble using titanium perforation and a higher quality packing and each silencer cost around £200 and is easily repackable... it ended up 96db at 5000rpm which is pretty good for a free flow Noble system and still sounds very throaty... might be worth exploring doing something like this on the Ultima.
The silencers were straight through but had a special perforation inside that helped capture the gasses rather than have a z trap like the ultima ones.... unfortunatelly like the Ultima ones the silencers need repacking regularly as they are so close to the headers it blows and burns the wadding out.
Must admit Id use different silencers if I was to do it again... I just had some made for my noble using titanium perforation and a higher quality packing and each silencer cost around £200 and is easily repackable... it ended up 96db at 5000rpm which is pretty good for a free flow Noble system and still sounds very throaty... might be worth exploring doing something like this on the Ultima.
Should add that we measured the noise during making the system, with the new style silencers the car went from 108db to just under 105db... the extra length and balance box got it down another 4db.... so you could just get your silencers repacked and have something made like i had to go behind them.
Worth noting that I had added in around 1-1.5 metres of length including bends and the balance box was actually the two pipes coming together along a straight going the same direction so wasnt a balance pipe or x trap.
I loved the sound the car made... yes it was more quiet, but it was also deep and meaningfull and really made some loverly noises on over-run... The flames it produced really were impressive.
Also worth remembering that a while back an Ultima caught fire on track due to the heat build up when it was using those bolt on things that go in the tail pipe... from memory it ruined the rear clip!
Worth noting that I had added in around 1-1.5 metres of length including bends and the balance box was actually the two pipes coming together along a straight going the same direction so wasnt a balance pipe or x trap.
I loved the sound the car made... yes it was more quiet, but it was also deep and meaningfull and really made some loverly noises on over-run... The flames it produced really were impressive.
Also worth remembering that a while back an Ultima caught fire on track due to the heat build up when it was using those bolt on things that go in the tail pipe... from memory it ruined the rear clip!
Slow M said:
Rusti Evo said:
...Repacking the standard boxes works OK but the packing has only a very short life. Tried a variety of materials - all useless...
Have you tried bronze wool? B
The problem appears that whilst particularly the Inconel would have an unlimited life, metal wools are larger in cross section compared to S-glass or Acoustifil fibres and is consequently not as good at absorbing energy.
Rusti Evo said:
Slow M said:
Rusti Evo said:
...Repacking the standard boxes works OK but the packing has only a very short life. Tried a variety of materials - all useless...
Have you tried bronze wool? B
The problem appears that whilst particularly the Inconel would have an unlimited life, metal wools are larger in cross section compared to S-glass or Acoustifil fibres and is consequently not as good at absorbing energy.
B.
robm3 said:
MarkWebb said:
Rob
I have read your previous and looked into supertrap. However I am not happy bolting them onto the back of my car for all to see and I have read some horrendous stories of power loss depending on what you have to set them at to get the noise down.
I would of course be keen to hear how you get on.
Absolutely agree, it does seem a well set up muffler can beat what I'm going to do. I intend to run without the Supertrapps but only fit them when and where needed.I have read your previous and looked into supertrap. However I am not happy bolting them onto the back of my car for all to see and I have read some horrendous stories of power loss depending on what you have to set them at to get the noise down.
I would of course be keen to hear how you get on.
Edited by MarkWebb on Tuesday 9th February 12:49
It's just I'd hate to get banned at a trackday, it's happened once to me before in a Lotus sport 160(Oulton Park) and I was gutted.
I'm sure powerloss will occur but hey, I got plenty to give away anyhow (even do trackdays with the A/C on in summer)
Here's some discussions on the supertrapps:
http://grassrootsmotorsports.com/project-cars/1992...
http://sccaforums.com/forums/thread/283518.aspx
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