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That guy
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Discussion Starter · #1 ·
This is going to be an odd question, so bear with me.

Im not worried about performance first and foremost.

I know changing the length and shape of a canister as well as packing can all alter the tone of the exhaust.

I want to know what is out their that can change the entire sound exhaust produces.

I don't mean louder, or deeper, I mean what would it sound like if I stuck a fucking kazoo, or some shit into an exhaust pipe.
Has anyone tried to play with the flowing exhaust gasses as a means to produce specific tones, or sounds?
 

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Is my bike ok?
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Some of the old timers at the drag strip used to CLAIM that they would string guitar wire between the collector bolts of their headers. Supposedly, if you got ''lucky'', it would create some sort of weird soundwave that was capable of cracking windows at full roar.

Always seemed like a fun thing to try. I'll let you have at it. :D

But no. I've never stuck a kazoo in my tail pipe. I don't care what she told you...
 

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That guy
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Discussion Starter · #3 ·
That's what Im looking for is crazy ideas like that.

I understand that exhaust is more than just air, its also a sound. An explosion to be exact, so the original sound the crack or bang of a cylinder firing will always be there, but something else to take that bang, and make it sound unreal all together.

I will not however, be shoving a kazoo up the tail pipe, least not mine.

Im trying to remember music class in elementary school, woodwinds, fluts, clarinets ect, hell whistles kazoos, all of them in some way use air flow to produce a sound. So it should be easy to change the sound coming out the tail pipe with some simple expiramentation.
 

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I think im lost
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Well as far as I know we have never done anything to the exhaust end
But madman has stuck one of those musical hoses into the intake of his sunflower. There is a video of it floating around somewhere

Shiny I was always told it was a "d" string out of a piano to break glass...Lol
 

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I had this POS chopped muzzy can on my r1 and it sounded like an empty soda can was stuck on the end of the mid pipe. Really annoying.
 

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lɐʇuǝɯᴉɹǝdx&#4
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There's been a lot of research done on exhaust sounds, but not much is published because its used to make money. Usually it is aimed at cancelling unwanted noises, and creating resonant pulses at desired frequencies to improve power.

Setting up resonance at a specific tone is a BAD idea. Its a common characteristic of cheap 'can' mufflers, and is called drone. You want resonance in your headers, but then the muffler is supposed to ... well, muffle that. In fact, many commercial mufflers have resonant chambers that are positioned to CANCEL noise at specific frequencies, by creating resonance that is out-of-phase with the incoming noise.

If you want to mess around it it, what you are basically looking at is Helmholtz resonance, and you'll find a lot of information, much of it applied to speaker enclosure design. You might also be able to use primary resonance and a reed, like an organ pipe does. Either way, the sound would drive you NUTS on the highway, and would do near nothing at idle.

Another option for creating sound from pressure that is NOT dependent on resonance is the method used by air raid sirens, and which causes turbines to whine. Basically you have a spinning object in the path of the moving gas that (from the perspective of the listener) chops it up into pressure pulses. They actually sell fake turbo noise makers for this. I doubt that's something you want to imitate, but it might be fun to try weird ass blade configurations (like chopping out some blades on each side, or filling the gaps between a few with high temp tape, or running a couple of them side by side) on one of those to see if you can get a tone you like. Again, its gonna be louder on the highway than at idle.

Then youv'e got stuff like the hinged metal flaps that cover the tops of vertical tractor pipes to keep rain and mice out, weighted so they get pushed open by exhaust pressure but close on their own. These make a lot of clanky jangling at idle, but as speed picks up they just stay open. I've seen them used cosmetically on cars and trucks, maybe some motorcycles. IMO its a bit tacky, but I'll admit it catches my attention; the highly irregular motion and noise can be almost hypnotic.

Personally, I like my exhaust system to be as quiet as possible when I'm not trying to make noise. When I build my exhaust system, I plan to have a nice big chamber after the collector that flows into plenty of silencer; simple, quiet, and low back pressure. But between the collector and all that, there will be one of these- a cable actuated exhaust cutout that effectively convers the system to straight pipes. (And yeah, as I read the laws in my state, that is totally illegal. But so is basically ANY exhaust modification, even if it makes the system QUIETER. Its all a matter of not giving the cops a reason to ticket yah for it.)



Should be extra fun if I ever install a nitrous kit.
 

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UnicycleMode
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Back before I got into bikes I built alot of car exhaust systems. The biggest factors in how they sound is wall thickness of the tube you use, you can also experiment with tapering a large diameter to smaller or the other way around too. The amount of curves in the plumbing between head and exit, collector length plays a huge part on a multi, if you want to get really crazy you can mess with primary lengths to get different pulse tones from the collector point.


Diameters, lengths, and mid pipe size are the major factors in weather an engine sounds like a kazoo or a full on race bred machine. ;)
 

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That guy
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Discussion Starter · #10 ·
Well I know this particular bike comes with what appears to be a yoshimura exhaust 4-1, I would rather not change the head pipe put.

But Im open to ideas to modify the existing head pipe to alter tones or sound waves, I will have to try the guitar string, or piano wire on the header bolts though. Not wanting to break glass, just wanting something entirely different sounding for exhaust.
 

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lɐʇuǝɯᴉɹǝdx&#4
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My guess on the wire thing would be that it affects the flow of exhaust gas as shown in the image below. The type of wire wouldn't matter much, could even use welding rod. The 'piano wire breaks glass' claim might be a due to thinner obstacle resulting in smaller, tighter votex patterns and so higher frequency. Or its just that fooking loud.



I can see it making a lot of noise with straight pipes, but I'd expect any decent muffler to cut down on such vortex related noise. That's pretty much the purpose of a muffler.
 

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Is my bike ok?
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Hi guys, I am sorry for such ,may be , stupid question but, can anybody say what downpipes can be used on sc33 '96 instead of originals. This is because mine are rusty and quite bad condition. second is that originals are pretty ugly for naked bike if not using belly pann.... my opinion....
Thanks in advance
 

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hate us cuz they ainus
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Firing order and the intake runners have a lot to do with your exhaust note too. I remember back in the day the SBC crowd were swapping two cylinders with each other. Made it sound more like a sbf
 

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I had an aircooled 1980 RD250 at one time and it was fitted with a set of expansion chambers that were made for a race bike , it didnt have any end cans just the pea shooter outlet pipe it sounded awesome as you cracked the throttle open but on a steady run it was a bit annoying, in the end I had to put some end cans on it as I got pulled at college and told to quieten down the bike or they couldnt have it on site, so I got a couple of bean cans and cut a hole in the top and bottom emptied them stuffed them full of fibre glass insulation drilled a couple of holes in the pea shooter end pipes and pushed the bean cans on, held them in place with some jubilee clips and it quietened it down loads and thankfully it didnt make a lot of difference to the performance.
 

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Feckin Eejit!
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I have seen a muffler (made by Mugen I think) for the Civic ricers where the pipe enters the muffler then exits, then comes back on itself & enters the muffler again before exiting out the back of the car. It changes the sound dramatically & even sounds quite good IMO.
There ya go...http://www.ebay.co.uk/itm/Genuine-Mugen-integra-DC5-exhaust-/281248593902?hash=item417bb8f7ee
Mugen Twin Loop


https://www.youtube.com/watch?feature=player_detailpage&v=09zhP3epBrw

I'd like to hear what it sounds like if the can were CF instead.
 

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Feckin Eejit!
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That's literally just a standard twin run exhaust with the end caps taken off. Not particularly different, really. Just looks strange.
2 in / 2 out with an "out" routed to an "in"

Fun bit of 90's "JDM" harware that didn't make it to the states much. I don't think the Mugen stuff got an official reseller here till the mid-90's and then it only just started to dribble in.
 
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