| [ Total Views: 1552 | Total Replies: 20 | Thread Id: 81763 ] |
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 bus914
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 posted on February 2nd, 2010 at 07:39 PM |
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Stock, quiet, multi - chambered Motorbike Mufflers - Results are in
If a bike makes 135HP at 10000 rpm with two mufflers, but a modified VW with double the bike's displacement makes 60HP at 4000 rpm, would it need one
bike muffler or two?
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sander288
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| posted on February 2nd, 2010 at 07:49 PM |
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If a UFO came down from space and zapped you with a red laser and then a green one which one would hurt more...
its more than the muffler.... and one should surfice
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bus914
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| posted on February 2nd, 2010 at 07:52 PM |
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Then tell me about the "more" part, that's what I'm after.
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 barls
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| posted on February 2nd, 2010 at 07:55 PM |
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its the system as a whole mainly its from the heads back.
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bus914
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| posted on February 2nd, 2010 at 08:09 PM |
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So assuming the VW's 4 into 1 header is more restrictive, including the tight bend into the muffler, does that indeed mean that one will suFfice?
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Phil74Camper
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| posted on February 3rd, 2010 at 08:40 AM |
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You don't normally see VW exhaust systems with more than one muffler. There are 4-into-1 systems that then branch off to a muffler at each side, but
they have no advantage over 1 muffler. 2 mufflers only work when they are in series, not in parallel.
A motorbike muffler ought to be more efficient and quieter than, say a fibreglass 'hot dog' style single muffler, and is around the same size.
The RPM range of VW engines is a lot less than motorbike engines. Bike mufflers are designed to quieten the 10,000+ rpm screams that VW engines will
never produce. How quiet are bike mufflers up to, say, 5000 rpm, which is what the VW engine will do?
What sort of VW engine are you planning to put a bike muffler on? Stocker, hot street, race??
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dangerous
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| posted on February 3rd, 2010 at 09:05 AM |
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If I recall correctly, Jeff Unwin used a bike muffler on the 2213cc(?)
hellbug back in the early 90's(?) when he ren a Raleigh Raceway near Nambucca Heads.
Car was still fast, even with a loose intake manifold, and sounded awesome.
| Quote: | Originally
posted by westi
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Sides
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| posted on February 3rd, 2010 at 09:29 AM |
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I know of a couple of hot beetles that are getting around with bike muffler's on 'em... Gracey (on here) being one of em... and they're all getting
good results.
The local muffler dude who's also into racing (BMW's rather than VW's unfortunately) was telling me that a single, superbike style disassembleable
(is that even a word?) muffler would work brilliantly on a VW...
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squizy
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| posted on February 3rd, 2010 at 10:02 AM |
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Pete Muhm used to run a bike muffler on his Cabrio in the 80's. Knowing Pete, it did f all.
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71-BEETLE-SEDAN
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| posted on February 3rd, 2010 at 05:45 PM |
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I was gunna do it but i went the cannon way, i think joel used to run one like a motor bike one on his black bug.
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greedy53
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| posted on February 3rd, 2010 at 06:04 PM |
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What happened to the space ship
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mnsKmobi
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| posted on February 4th, 2010 at 11:43 AM |
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| Quote: | Originally
posted by bus914
If a bike makes 135HP at 10000 rpm with two mufflers, but a modified VW with double the bike's displacement makes 60HP at 4000 rpm, would it need one
bike muffler or two?
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Why do you want to do it? I remember someone using Harley mufflers b/c he could get them v. cheap. (I think he had two) Other than that I can't see
any advantage.
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DubCty
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| posted on February 4th, 2010 at 08:22 PM |
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| Quote: | Originally
posted by sander288
If a UFO came down from space and zapped you with a red laser and then a green one which one would hurt more...
its more than the muffler.... and one should surfice
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bus914
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| posted on February 4th, 2010 at 08:25 PM |
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| Quote: | Originally
posted by mnsKmobi
Why do you want to do it? .. someone ...could get them v. cheap.
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High quality units can be had for a song. It seems a motorcyclist wouldn't be caught dead with a stock pipe, so they rather give them away.
| Quote: | Originally
posted by Phil74Camper
....Bike mufflers are designed to quieten the 10,000+ rpm screams ....
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The ones I've got came of a 4 stroke 2cyl bike, with one muffler per cylinder. This means that each muffler gets only 5000 pulses at 10000rpm. This
will be the sweet spot, tuned to match the engines horsepower peak.
As the bike has roughly half the displacement, each of the bike's pistons displaces a very similar volume to each of the car's.
A 4 stroke 4cyl VW will fire two pistons on every revolution. So at 5000rpm a single muffler in a 4 into 1 setup will get 10000 pulses ...too much.
5000 pulses will occur at just 2500rpm. ....maybe good for a Kombi.
So you do need two mufflers, in a 2 into 1 config. That will give 5000 pulses at 5000rpm. Perfect...just as the engineer intended.
The usual setup for a VW with this combo is called cannons.
.....but, because the firing order is 1,4,3,2 the pulses are not evenly spaced with typical cannons, ie. cyl 1 exhaust will not make it out of the
pipe before cyl 4 exhaust enters the muffler, and then its a long wait while 3 and 2 fire before 1 fires again.
Conclusion, these mufflers won't work, unless a 2 into 1 setup is fabricated that links the even cylinders together and the odd ones together.
Or so I think anyway 
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BiX
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| posted on February 5th, 2010 at 03:51 PM |
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If you go the after market route, most motorbike mufflers come with a baffle that is easily removable. Though most after market ones cost between 500
and 1200 new....
If anybody in brisbane wants, I have a std muffler from a SV650 they can have to play with. Its got some gravel rash, but hidden under a car it would
be fine. It comes from a 650 V twin, that spins to 12000 rpm (for your calcs above). it does have the standard baffle inside, so makes thisng pretty
quiet and I think would restrict flow.
Cheers
Drew
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bus914
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| posted on February 24th, 2010 at 09:15 PM |
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My post above may have read like a convincing argument.
....but... I now think that one muffler will work a treat.
The reason being, that the bike has peak a torque figure that I think is very near what I get from the car. This means that the bike has near 100%
better volumetric efficiency. So each pulse from the VW engine will have half the volume.
I'll post the results when available if anyone is interested.
The donor bike looks like this by the way:
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bus914
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| posted on December 7th, 2010 at 04:15 PM |
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Got one fitted, it runs good but still sounds like a WWII fighter plane. See the pix below and listen to it here:
 on Youtube
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Sides
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| posted on December 7th, 2010 at 04:20 PM |
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Sounds all right... good that you gave it a try !!!
Don't suppose you've gotten a noise reading off of it ??? (free revving at a stable 5000rpm measured at 5m is a common one to come across at
circuits)
Also keen to hear the details, specs, costs etc. if you don't mind sharing...
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bus914
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| posted on December 7th, 2010 at 04:28 PM |
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No noise reading, haven't even tried over 4250rpm. (electronic rev limit).
Details:
Right side OEM muffler for 1997 Ducati 916 SPS $75
SS bend, flange and fitting $100
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HappyDaze
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| posted on December 7th, 2010 at 04:39 PM |
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Anyhow Shaun, what WOULD hurt the most - a red laser, or a green one
I suppose getting run over by a Ford Laser would be even worse, red or green.
I'd rather wear a Beetle out by racing it than by polishing it!
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SuperOwen
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| posted on December 18th, 2010 at 07:36 AM |
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A bit hard to tell from the video but it sounds quite nice to me. Better clearance than fatboy setups etc as well. Something else to play with is the
length of the entire system, I found that made a big difference to the note on my old 1835.
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