miegru
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| posted on 8/2/07 at 12:47 PM |
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Making an exhaust
I was getting a bit tired of constantly repacking my exhaust and the noiselevel when driving.
So I build myself a simple exhaust (just a test one using old bits and pieces). Aim is to see how that works (and to learn myself to tig-weld :-))
It is MUCH quieter and I don't notice a powerdrop. Does anybody here know if and how much power is taken away by such an exhaust?
The design:
A 130mm diameter tube, 650mm long and entry and exit both 60mm in diameter. The tube is split into three chambers:
1: 150mm long. In this chamber the entry flows in and the fumes can go through a perforated 60mm diameter pipe of 110mm to the next chamber.
2: 450mm long. The fumes enter this chamber through the end of the perforated pipe as mentioned above. The fumes exit to the next chamber through 6
25mm diameter tubes, all between 250 and 350mm long. These tubes are attached to the barrier between chamber 2 and 3 and are hanging freely in chamber
2
3: 50mm chamber. Fumes enter via the 6 tubes and exit through the 60mm exit.
Total weight is 300grams heavier than the Laser open one I have.
Total opening everywhere is 60mm. So how will this affect power and how much?
It sure is quiet!
Mies.
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David Jenkins
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| posted on 8/2/07 at 01:03 PM |
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I'd be interested to know, as my exhaust is still intrusively loud even though I've recently repacked it. I wouldn't mind losing a
few BHP if I could reduce the dB a lot more!
And before anyone suggests it - I don't want to fit a stock car silencer as they usually look 'orrible on the side of a 7.
David
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MikeR
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| posted on 8/2/07 at 01:23 PM |
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Vizzard made an interesting discovery / published known knowledge (don't know which).
If you have your exhaust enter a chamber that is big enough to hold the volume of gass escaping from all your cylinders it will allow the exhaust to
breath freely & reflect the pulse. You then send the gass via the 'what ever' to quieten it. Sounds like you've done something
similar by accident
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miegru
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| posted on 8/2/07 at 01:35 PM |
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Thnks for that knowledge. I plan to make another one (with more pleasing looks..). Will use that info.
I know of one place in the Netherlands where I can buy part for the exhaust (main pipe, end caps en internal barriers, etc.). Anybody know of a cheap
UK supplier? Want to compare prices.
Rgrds,
Mies.
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MikeRJ
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| posted on 8/2/07 at 02:05 PM |
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quote:
Originally posted by miegruSo how will this affect power and how much?
It sounds like you have re-invented the helmholtz resonator type silencer. Most car exhausts have at least one silencer that works in a simmilar way,
each chambers is sized to resonate at a particular frequency that requires attentuation.
It does give more back pressure than a simple absorbtion type, but how much power that is costing you is anyones guess. If you are only losing 4-5bhp
or so it would be very difficult to notice any difference on the road.
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greggors84
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| posted on 8/2/07 at 02:13 PM |
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There was a great article about exhaust in last months PPC. Definately worth a read.
Chris
The Magnificent 7!
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02GF74
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| posted on 8/2/07 at 02:39 PM |
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quote:
Originally posted by greggors84
There was a great article about exhaust in last months PPC. Definately worth a read.
errm, cough any chance of a scan cough
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suparuss
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| posted on 8/2/07 at 02:47 PM |
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these guys do something very similar with a bypass to make it straight through on demand. most of
any benefit for scavenging etc is done at the collectors after the header so i cant see there being much of a power loss either. unless you are
running a cam with overlap in which case back pressure pulses would be quite important.
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greggors84
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| posted on 8/2/07 at 03:52 PM |
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quote:
Originally posted by 02GF74
quote:
Originally posted by greggors84
There was a great article about exhaust in last months PPC. Definately worth a read.
errm, cough any chance of a scan cough
No there isnt...
You have U2U 
[Edited on 8/2/2007 by greggors84]
Chris
The Magnificent 7!
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907
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| posted on 8/2/07 at 11:29 PM |
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The loss of an odd horse or two is not an issue for me.
I've made a few cans in my time but they have mostly been the straight through re-packable type,
but only because that's what people want.
Personally I wouldn't fit one to my own car, preferring a through design that doesn't require repacking.
IMHO you can lose more power from the drag of wide tyres than you will from using a moderately baffled can.
Just my 2p
Paul G
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David Jenkins
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| posted on 9/2/07 at 08:03 AM |
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In my case, the exhaust note is starting to irritate ME, let alone the neighbours...
...I'm seriously considering a quieter exhaust.
David
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DanP
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| posted on 11/2/07 at 06:10 PM |
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I belive milner offroad can supply the parts you need: http://www.milneroffroad.com/PIPE.HTM
I've used them for tube and they seemed good.
HTH
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