There was a good article on exhaust systems called "Exhaust Systems
Demystified" by David Vizard in the May 2005 issue of Popular Hot Rodding.
Outlines how to build a "zero loss" system.
My calculations from the information given:
1 3/4" pipe = 112 hp
1 7/8" pipe = 130 hp
2" pipe = 148 hp
These values are for a system with an equally well flowing resonator and
muffler.
Vizard states in the article that the resonator is a "pressure wave
termination box" and as such is the end of your "tuned length exhaust
system". It is placed in the system close to the header and BEFORE the
muffler.
He also states that using mufflers/pipes larger than required will not gain
any horsepower but WILL make the system louder.
So... Where does this leave us? I am, optimistically, hoping my 1800cc
stroker will make around 130 hp. That puts me at a 1 7/8" exhaust system.
Although the pipe is not hard to find, after a week of looking I have
ordered a 2" in/out Borla straight through muffler, and a 2" in/out
Flowmaster "Hushpower II" resonator. Here, even to get these parts in 2" is
a 4 week wait. They don't normally deal with stuff that small......
I am unsure of the HushPower resonator, from the diagrams on the internet it
looks more like a muffler....but it was the only performance resonator I
could find, and I am trying to get a quieter system.
Hope this helps. If you have the chance, look up and read the article, there
is a whole lot more information than I have outlined here, and I prefer if
someone doublechecks my calculations. I am a fan of science, but not much of
a mathematician.
Cheers
Daryl
From: "Ronnie Day" <ronday@tlabgalaxy.net>
Subject: Backup Lights & Exhaust Setup?
> Next question - How large an exhaust pipe can easily fit through the OEM
> holes in the frame? The car has headers and we have a new flex pipe header
> reducer so I'm thinking we should be able to use pipe just slightly
> smaller
> than the holes and fairly rigidly mounted to keep it from banging into the
> sides of the holes?
>
> It looks like there's an OEM style muffler under the driver's seat and a
> glass pack behind the rear axle. I'm thinking a single turbo style behind
> the axle. I did this on our first 510 in the early '70s and even had a
> flange just in front of the muffler so I could swap it for a straight pipe
> for track work. That probably didn't have any real effect on power, but it
> sounded cool and sure turned heads when I'd idle back through the Hickam
> auto hobby shop on my way to the track.
>
> Ideas/suggestions on both questions appreciated,
> Ron
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