Don:
I believe Kas makes that assertion based on cross sectional area
of the pipes:
For a dual 1.75" system, area = 4.8 in^2
For a single 2.5" system, area = 4.9 in^2
So the improvement is tiny, about 2%, for a single 2.5" pipe
over a dual 1.75" pipe.
I believe that the stock system is 1.75"x2 on the later cars, correct?
The early cars had
1.75"x1, so they were poor in terms of exhaust flow. The factory went to
the dual European
system on the later US cars as the emissions requirements began to choke
all the power
out of the engine. The factory had to start putting in the better parts
to make up for
the loss.
In general the muffler is the main restriction, not the pipe. So
going to
a true dual exhaust with two mufflers, even if the pipes are 1.75",
would probably
way out perform a single 2.5" system with one muffler.
Evaluating the system on the basis of pipe diameter is a way to
get hard numbers,
but far better is to get a rated flow for the muffler at say, 18" of
water pressure drop.
None of the exhaust system manufacturers are talking about that though.
You need to go to
someone's book to get comparisons. I have only ever seen David Vizard
compare the flow
numbers for the various mufflers.
Just looking at the pipe diameter is looking at only 20% of the
picture, when you need to
look at the muffler to get the remaining 80%. Some of the aftermarket
mufflers are
surprisingly weak in terms of flow.
Enough babbling.
Cheers,
Vance
-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net] On
Behalf Of Don Malling
Sent: Wednesday, April 21, 2004 2:18 PM
To: Lizirbydavis@cs.com
Cc: 6pack@autox.team.net
Subject: Re: ANSA vs Monza for TR250/TR6
Hi Joe,
According to Kas and others a single 2.5 inch pipe is better than two
pipes. I'm not sure why. I also think the Falcon is 2.25" rather than
2.5" so I'm not sure of the implication of that. Exhaust systems and
Headers are black magic to me. I'm just doing what I read and what folks
tell me :-)
Don
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