At 08:31 AM 11/8/2000 -0500, Edwin McCarroll wrote:
>Can anyone describe what a 'supertrap' exhaust component looks like, its
advantages over other types, and does its applications cover older cars
like MGA's, Jaguars, etc.? Apparently there is a built-in adjustment
that regulates exhaust flow?
So nobody got back to you on this one? Sorry, I've been pretty busy today
(and tonight).
SuperTrap is a registered trademark, and a brand name, so it it unique and
easily recognizeable. The thing is usually installed on the end of an
oversize straight through exhaust pipe, with nothing else between it and
the exhaust manifold, and often used in conjunction with tubular headers
for minumum exhaust back presure, so you can get the largest gas flow at
the highest throttle setting and engine speeds. The device is loosely
called a muffler, but in fact the way it works it effectively uses itself
and the entire exhaust pipe to provide (some) muffling effect. Quite often
used on motorcycles as well as automobiles.
The SuperTrap is often (but not always) shapped like a narrow megaphone,
nearly as small as the connecting pipe at the inlet, and probably not more
than 4" to 5" diameter at the outlet end, and will have a full bore
straight through perforated pipe and (usually) fiberglass packing (or maybe
wire wool) similar to a common glass pack muffler. On the outlet end there
are a number of flat round disks installed across the outlet opening. The
last disk at the back is blank (solid), but the other disks have hole in
the center like a doughnut. Interspersed alternately between these disks
will be small spacers (or possibly just embossed bumps on the disks) such
that there is space for the exhaust gas to escape radially between the
disks. The disks are held in place by several long thin screws. The more
disks you stack on the end the easier it is for the gas to escape, so the
lower the back pressure. Fewer disks leaves less escape space for the gas,
so higher back pressure.
Lower back pressure generally yields the most torque for high engine
speeds, so you can add more disks when you go racing, but with very little
back pressure it might run like crap at low speed. A littler higher back
pressure will probably make it run better and have more torque in the lower
rev range, so better for daily street driving, as well as being quieter (or
at least a little less loud). Reducing the exhaust back pressure also has
the effect of leaning out the fuel mixture with a standard carburetor, so
proceed with due concern for re-adjusting the mixture as required if you do
not have a modern electronic feedback fuel control system.
These things are very popular with folks who take their street car racing
on weekends, but still need to have it running well for daily street use.
The adjustment available here also makes it possible to compromize when
necessary to meet local noise ordinances, which may be enforced at certain
racing locations (as well as on the street).
For more information, try this link:
http://www.supertrapp.com/automotive_page.htm
and keep poking links and reading until you have it all.
Barney Gaylord
1958 MGA with an attitude (nad new glass pack every 50,000 miles)
http://www.ntsource.com/~barneymg
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