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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