Re: Exhaust systems - More Velocity

From: Cale (vencomatic@ameritech.net)
Date: Wed Apr 19 2000 - 21:11:36 EDT


Andrew - my pleasure - I'm enjoying this!
The baffled mufflers such as Flowmaster claim to achieve scavenging via
the separation and synchronized merging of the exhaust gas pulses.

Whoa gotta go. I'll give a more complete response later
Cale

Aajaynefour@cs.com wrote:
>
> Cale,
>
> Thanks for the velocity vs. pipe diameter plot. Reminds me of when I was
> studying fluvial systems. Water slows waaaay down the closer you get to the
> banks. I hadn't even considered that the same phenomenon occurs in exhaust
> systems.
>
> I now understand the accel/decel phenomenon that occurs in the cats and some
> mufflers. I say some mufflers because the straight through ones like Borla,
> Ultra-flow , etc., seem to have the same diameter of "pipe" all the way
> through. There is no "chamber" for the gasses to expand in and thereby slow
> down. These types of mufflers would obviously seem to offer better flow than
> chambered mufflers. However, I have been looking into the Flowmaster
> mufflers and they seem to use baffling, diverters really, to achieve a
> pressure differential. If I understand it correctly, the lower pressure on
> the EXIT side of the muffler helps to draw out or extract the exhaust gasses
> from upstream in the system. If this is so, then this type of muffler would
> seem to offer advantages over straight through types and obviously the garden
> variety baffled mufflers. Any thoughts on this?
>
> Back to pipe diameter for a moment. You mentioned that you do not
> intuitively feel that we should be using smaller diameter pipes on our
> systems (I agree intuitively and a good deal of experience from others seems
> to bear this out). What I am deducing from this is that our systems are
> restrictive enough from the factory that we can successfully go to larger
> diameter pipes (within reason) and still maintain critical flow velocity at
> lower RPMs. Let me know what you think.
>
> Sorry if this discussion causes any cranial detonation anywhere but I am just
> trying to understand the theory behind performance exhaust systems.
>
> Thanks,
> Andrew



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