John:
A leak would reduce back pressure, and have the potential to
improve performance if the car calibration is correct. HOWEVER, the leak
would need to be good sized. There is a safety concern with a leak, as
carbon monoxide becomes a concern.
What is more likely is that the leak changes the needed
calibration for the carbs and results in a lean mixture, potentially
reducing performance. I would not expect there to be a noticeable change
in idle quality or smoothness (although if the noise level is up
appreciably, the perception may be that there is a reduction in
smoothness.
Exhaust leaking under the car has the potential to leak into the
cabin and result in poisoning. Not a problem with the top down, but with
the top up and the windows rolled up things become unsafe. This is
because the interior of the car tends to be at a lower pressure and so
will "pull" the fumes in. So get that leak fixed.
If you are installing a new OEM style system, consider having
the joints welded. I installed new OEM style pipes from Moss and found
that the ends had been over flared, so clamps could not get pipes
sealed. I had to have everything welded to get rid of the leaks.
If your system is not an OEM style, AND you have a *good*
muffler (many of the aftermarket systems are very disappointing in this
regard) you can expect a 5% or more pop in horsepower if you recalibrate
your carbs appropriately. A low restriction muffler will make the
mixture go lean - and re-tweaking the mixture will be necessary for
optimum performance.
Cheers,
Vance
-----Original Message-----
From: owner-6pack@Autox.Team.Net [mailto:owner-6pack@Autox.Team.Net] On
Behalf Of John VanNorman
Sent: October 30, 2007 9:43 AM
To: 6-Pack
Subject: [6pack] exhaust leak question
<snip>
The exhaust system is shot and we have a
new one to install, but it got me thinking - other than sound, what,
if any, impact does an exhaust leak have on engine performance? I
understand the positives of reduced backpressure and such with free
flow systems, etc, but I'm thinking more in terms of things such as
idling quality and smoothness. And how about the carbs, would an
exhaust leak impact the performance of the carbs?
John V.
1974 1/2 TR6
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www.vannorman.no-ip.org
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