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Discussion Starter #1
can an exhaust chamber be any shape? cylindrical would probably be the easiest to make but what restricitons are there? i know flow characteristics would be an issue as well as volume but if a chamber can be made to flow as "freely" as cylidrical one would that mean it can be any shape?

thanks i just have this idea swirling in my mind.

ps. i havent seen the inside of a 749 or 999 exhaust so im not sure what shape or whats inside for that matter
 
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for a given cross sectional area a circle has the least wall length/perimeter or whatever you want to call it. therefore it will give the least losses due to the boundary layer drag.
 
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Re: (brad black)

so drag would mean more pressure. if so would a smaller volume chamber compare to a larger cylindrical canister? if so by going smaller would that sacrifice noise damping?
 
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Re: (doughboy_748r)

boundary layer drag is that the layer up against the outside of your pipes travels at a different speed than the center of the flow, because of temp difference, flow restrictions and more stuff i don't understand.
 
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Re: (doughboy_748r)

While boundry layer effects certainly exist, in the real world they are such a small percentage of the total restriction (in an entire exhaust) that they can be ignored. Non-round shapes are a pain to manufacture and work with which is as much a reason to use round tubes as anything else.

The chamber can be any shape. Some are better than others depending on what you're trying to do. I'm not sure what you mean by "would a smaller volume chamber compare to a larger cylindrical canister?" Compare how? For the most part the attenuation depends on volume, not shape, though there are effects due to the change in cross sectional area where a greater change is better for attenuation. But you still need volume, so to answer your next question, yes, in general a smaller chamber will be louder.

I haven't seen the inside of a 999 exhaust either, but I'd guess it consists of round tubes inside a stamped or hydroformed shell, with a couple partitions in there to create seperate chambers.
 
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Re: (DesmoDog)

You will also see that square edges and hard folds are not common inside as this does create a lot more boundary layer drag from adjacent surfaces hence creating flow disturbance, a clean flow line makes the gases flow, tighter bends formed properly don't have to bigger impact but the sizing does, dependant on where you want you power range you can up or downsize the pipe (within reason) to assist shifting your power curve along with the usual other items of remapping etc.


Another factor is where balance pipes are placed, this can greatly effect where you power delivery comes in, when I gutted the MH pipe I found out all sorts of information for performance enhancing exhausts etc, when it really comes down to the hard ass nitty gritty, an open style muffler and pipe with good clean flow lines and adequate size is all you need, you can tune the fuel system to it with great results and for the average street rider you will find that great.

99% of pipe/muffler manufacturers claim all sorts of figures, truth is they are all very close and unless you do other adjustments to air intake and fueling the gains are minimal.

Sound is the biggest improvement for street use, unless you are up on cutting edge racing you can spend a fortune for not a lot.
 
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Re: (Monstaman)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Monstaman »</TD></TR><TR><TD CLASS="quote">

an open style muffler and pipe with good clean flow lines and adequate size is all you need, you can tune the fuel system to it with great results and for the average street rider you will find that great.


</TD></TR></TABLE>

pretty much what i was thinking. im also thinking along the lines of a MV type of exhaust.

thanks!
 
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Re: (doughboy_748r)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by doughboy_748r »</TD></TR><TR><TD CLASS="quote">

pretty much what i was thinking. im also thinking along the lines of a MV type of exhaust.

thanks!</TD></TR></TABLE>

Now that would be well cool!
 
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