"Doc Gas" who is a local exhaust expert who literally changed the sound of
Daytona, explains that exhaust is like a series of "eggs" being pushed out
of the headers. With the pulsations I wonder how effective the Bernoulli
effect is because of the interruptions of the total flow? An atomizer works
best with a constant flow. An exhaust header does not put out a constant
flow.
Wes
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> From: dferguso@ebmail.gdeb.com
> To: FastmetalBDF@aol.com, land-speed@autox.team.net
> Subject: Re: Exhaust Extraction
> Date: Tue, 4 Jan 2000 17:54:03 -0500
>
>bernoulli's principle is not dependent on having a small exhaust dump to be
>effective. the bernuolli equation shows that the decrease in pressure will
>be the same ( IF the engine is shut off ) weather the exhaust dump has a
>small diameter (area) or large diameter (area) for a given velocity of air
>rushing by . where the trick comes in is how fast are you compensating for
>(negating) this effect with the exhaust flow with the engine running. if
>your engine is forcing out enough exhaust compared to the area of the dump
>( a small collector), then the bernoulli principle looses its effectiveness
>and will reach a point where it no longer applies as the exhaust gasses are
>exiting the dump so forcefully that the air flowing around the car can no
>longer flow over the end of the dump. actually, the bigger the exhaust dump
>the better, since the venturi effect of the bernoulli principle can
>possibly work its magic over a much bigger area to hopefully compensate for
>the pressure and flow of gasses exiting the engine. besides the bernoulli
>principle, other factors such as the shape and orientation of the dump
>relative to the air flow over the end of it also play an effect on net
>pressure inside the dump via frictional and momentum interactions between
>the exhaust gas and the air flowing by the end of the dump. at wide open
>throttle bernoullis principle probably does not play a role in reducing
>exhaust pressure since exhaust will be exiting the dump very forcefully,
>but im sure the frictional force of the air rushing by the end of the dump
>may play an "extractive " or " venturi" role depending on the geometry and
>relative orientation of the dump.
>
>food for thought for anyone who cares, not presented as gospel physics -
>regards-
>doug @ black radon engineering
>
>
>
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