ChrisT
Club Retro Rides Member
Posts: 1,638
Club RR Member Number: 225
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extra exhaust silencingChrisT
@christ
Club Retro Rides Member 225
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Aug 15, 2009 15:51:14 GMT
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I'm in need of a little more exhaust silencing on the manta (too loud for me on long journeys and I'm guessing very annoying for the local residents as I'm shunting it around trying to get into the garage) but not sure the best way to do it. There's not realy much room for an extra box in the system, ground clearance being the main factor. Was wondering if I could put some extra packing in the back box as that's 3" bore compared to 2.5" for the rest of the system. If I got some 2.5" perforated tube, wrapped a bit of wadding round it and welded that into the back box would it make any difference?? have some exhaust pics that have probably been posted several times before....    |
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Aug 15, 2009 16:54:47 GMT
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If I got some 2.5" perforated tube, wrapped a bit of wadding round it and welded that into the back box would it make any difference?? Well, the short answer is yes, but probably not enough. At the end of the day, you've still got a 2.5" straight-through exhaust. The major parameters which affect muffler efficiency are volume and the path the gas flows take, ie. the design and number of baffles. Essentially, the muffler will probably be more or less the same. Rather than trying to add another muffler, you could probably get substantial improvements by trying a different muffler instead of your current one. Costs are the same, and weight is less. Don't underestimate the difference either, not all mufflers are created equal. As an example, have a look at this muffler test on Autospeed: autospeed.com/cms/A_0383/article.html As they show in the test, the difference between similar mufflers from different brands can be as much as 5dB, which is a LOT! Also, I found this article quite interesting too: autospeed.com/cms/A_0054/article.html |
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Aug 15, 2009 21:16:19 GMT
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Would you have enough room for a cherry bomb as the od is only an inch or so bigger than the tube dia?
Or replace the whole back box with as long a 2.5 inch cherry bomb as you can?
Both of mine are silenced with cb's only.
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Aug 15, 2009 22:45:51 GMT
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ChrisT
Club Retro Rides Member
Posts: 1,638
Club RR Member Number: 225
Member is Online
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extra exhaust silencingChrisT
@christ
Club Retro Rides Member 225
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yeah did think about them, at least I'd be able to 'tune' the exhaust note - would have to weld some flanges to the exhaust to make fit though. Would you have enough room for a cherry bomb as the od is only an inch or so bigger than the tube dia? Or replace the whole back box with as long a 2.5 inch cherry bomb as you can? Both of mine are silenced with cb's only. was going to say I don't want a stupid red painted silencer in my nice stainless system but having looked at their site I see they do stainless ones now - might have enough room for one. going to have a measure up later, ground clearance is one problem - finding a straight section long enough for a silencer could be another Found this on the 'bay - at 4" diameter it's quite small (cherry bombs are 115mm) and a good price. |
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I reckon getting rid of the 20" exit of yours would help.....sort of like taking the bell off a trumpet if you know what i mean.
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ChrisT
Club Retro Rides Member
Posts: 1,638
Club RR Member Number: 225
Member is Online
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extra exhaust silencingChrisT
@christ
Club Retro Rides Member 225
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Aug 16, 2009 11:15:23 GMT
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yeah, know what you're saying, I'm working on that one too - maybe twin 3.5" instead just been down to halfords to see what price they do the jetex custom exhaust parts... after asking for a price on a 'universal 2.5" stainless midbox' I was asked for the make, model and age of the car it's for?  told him but stressed it was a universal part I was after he started looking through his catalogue in the vauxhall section and then said it would be difficult to get a price on a sunday. I walked out at that point. |
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Aug 16, 2009 17:45:28 GMT
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ChrisT
Club Retro Rides Member
Posts: 1,638
Club RR Member Number: 225
Member is Online
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extra exhaust silencingChrisT
@christ
Club Retro Rides Member 225
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Aug 16, 2009 20:26:28 GMT
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^^^^cheers for that but already found the site, just checked out Halfords (being official jetex dealers) on the off chance they were cheaper.
just ordered one of their 'handy' silencers - shortest I could find at 250mm as there are no straight sections in my system any longer than that.
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Aug 16, 2009 20:34:39 GMT
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have you been on merlin motorsport site?
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Aug 16, 2009 20:36:29 GMT
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I had a straight through system with one silencer at the back which was pretty loud. I added a cherry bomb to the middle of the system and it really cut the noise, but it's still not 'quiet'. What you need is a silencer with baffles which will really knock the noise out. Probably worth looking for a car that uses an exhaust that big, probably a BMW, Merc or big saloon like that, and keep an eye out for a complete exhaust system on eBay. Then you can steal the silencer out of it and it'll be whisper quiet. Mine is reasonably quiet though; most of the noise is from the Webers.
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ChrisT
Club Retro Rides Member
Posts: 1,638
Club RR Member Number: 225
Member is Online
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extra exhaust silencingChrisT
@christ
Club Retro Rides Member 225
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Aug 16, 2009 21:29:59 GMT
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Don't want it to be whisper quiet - just cut out a bit of the noise at low revs. already got two boxes in the system, this third one should help without having to go down the route of using baffles have you been on merlin motorsport site? yep, everywhere on the 'net I could find that stock custom build exhaust parts - inc. merlin, DT and motorsport-engineering. Jetex were the only company with short enough boxes. With P&P they all seem to work out about the same price. |
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