Actually John, the H pipe only works when the rpm and exhaust
velocity are low. Once rpm and exhaust velocity get high, the exhaust
goes right past the H pipe. An X pipe on the other hand works at all rpm
for obvious reasons.
According to the Dr. Gas web page:
"Dr. Gas, Inc. has developed a new generation of crossovers that uses a
tangentially siamsed junction, in place of the H or over-and-under X. It
evenly splits, smoothes, and synchronizes exhaust pressures at all engine
speeds. The high and low pressure pulses in the two pipes are evenly
imposed on each other, leveling out the pulse time history pressure
differences between right and left cylinder banks. Re-synchronizing the
exhaust pulses reduces back pressure, cancels sound, and provides additional
scavaging. Tests have sound 6 dBa (75%) reduction in sound levels, and
increases of 10 to 30 hp, and up to 40 ft-lbs. of torque! Economy, and
throttle response are improved. Exhaust flow after the crossover is
completely smoothed out. The job the headers started is finished. One of
the most appealing benefits of this system is the modified exhaust note.
The deep growling and popping sound is replaced by a higher pitched smooth
sound. The exhaust note is similar to a 180 degree header system without
the nightmare of tubing."
Personally I like the modified tone with the X pipe. My Elky is the
second car I've used the X pipe on and when the rpm goes up it sounds like a
race car (to me).
cYa-
----- Original Message -----
Sent: Monday, January 27, 2003 12:44
PM
Subject: RE: [Chevelle-List] Muffler
and Pipe recommendations for 67 Chevelle
I am going with 50 series Flowmasters
and the H-pipe, with tailpipes exiting behind the tires. The purpose of the
crossover (H or X) pipes is to balance out the pressure to improve the flow
of the exhaust gasses. Some people argue that the X-pipe is better because
it forces the exhaust streams to cross each other whereas gasses (arguably)
only cross to the other side when there is uneven pressure with an
H-pipe.
John
Nasta
