We have a local guy, specializes in exhaust systems, "Doc Gas", He changed
the sound of Daytona for NASCAR with his crossover pipe. Interesting how
many now use it. He takes a very scientific approach to exhausts and is one
of the top people in the field. He describes the exhaust going through the
tubing as a series of "eggs" being forced through the pipes. That gives
something to think about. I have not been able to contact a couple of the
local racers who have worked for and with him on exhausts but I'll be
interested in their responses when I do. I'll pass along anything
interesting on the subject.
Wes
on 3/7/04 11:23 AM, Dave Dahlgren at ddahlgren@snet.net wrote:
> 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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