Exhaust system discussion.

["John G. Napoli" <john@xxxxxxxxx>]

> John N. had a comment about the need to enrich the carburetor if you
replace
> the exhaust with a less restrictive system.  I am not sure I agree with
that.

I don't want to start an argument, but this does need to be addressed.  If
you improve the exhaust enough to make a difference, you must compensate
with richer mixtures, whether carb or FI.  Yes, most engines are calibrated
on the rich side as a safety measure at WOT.  With 'better' exhaust you
begin to use up this margin of safety.  If you use this up and then continue
to run at heavy loads and WOT you risk burning a hole in a piston.

Carbs need fatter jets.  FI engines need different mappings.  Carbs can't
fatten their jets on their own, so I am puzzled by your statement that only
FI systems need recalibrating.

Now, if someone goes for 2 1/4 inch pipes instead of 1 7/8 and
low-restriction mufflers, they are not likely to run into problems.  But if
you add headers and so on, you will as you improve things.  This information
can be verified from any of the header manufacturers or speed merchants or
engine designers.

Happy New Year, All!!!

John