I have never bought into the back pressure theory making things better. I
will buy into having too much exhaust cam though or the wrong lobe
separation for the cylinder head. It is the reason many new cars have
variable cam timing as standard equiptment.
I do believe though that when talking about torque whoever has the greatest
area under the curve in the rpm range that the gearbox is set up for, has
the fastest car.
Dave
> -----Original Message-----
> From: Ed Van Scoy [mailto:lsr128@msn.com]
> Sent: Sunday, March 07, 2004 1:05 PM
> To: Dave Dahlgren; Land Speed List
> Subject: Re: Stepped Headers
>
>
> Dave,
> You said the magic word in your last sentance - torque. Naturally this is
> why we (some of us) are willing to spend large sums for custom designed
> exhust rather than $69.00 headers from J.C. Whitney. Yes, some engines do
> better with back-pressure - finding out just how much might be the
> aforementioned "black art" BUT I have heard Bernoulli's
> principle put forth
> as the reason NOT to step the pipes, and further, a step down (venturi)
> speeds up the fluid, thus exerting less pressure, increasing scaveging.
> Sounds good in theory, and when I am flying, I NEVER question Mr.
> Bernoulli's principle. But when it comes to the internal
> combustion engine,
> this just goes contrary to many years of experience. Again,
> thinking of the
> engine as an air pump........ Maybe I should have stayed in school ;-)
> Ed
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