>
 > Remind me to get back to you on this spark plug issue next week.  I
will be
 > speaking with an ex Mazda rotary guy who helped design the intake
system for
 > the LeMans engine.  The sparkplug question as well as the profile
shape of
 > the P-port are several answers I seek.  I happen to agree with about the
 > future of stricter EPA regs. in the future.
 >
 > Doug in Japan
 >

Doug,  If you get the chance, ask him if the LeMans engine intake was
ever operated at maximum length
at 9000 rpm.  I'm trying to develop a program for manifold design and it
indicated that the manifold would be in primary resonance at max length
at 9000 rpm.   Looked like second harmonic was used at all other engine
rpms.  Would help a lot if you could confirm this.

Tracy Crook

What are you using for intake air velocity of sound Tracy? I would be very
surprised if it was second harmonic. In the intake air the velocity (V)
of sound  is roughly 1,100 feet per second depending on temperature.

From Scientific Design of Exhaust and Intake Systems Page 82.
L = V x 180 / RPM  therefore L = in inches is 31.9 inches
with V = 1100 and RPM = 6200.

At 8000 RPM it is 24.74"

Here is a an actual dyno run of a copy of the actual Lemans P-port with
a 25 inch length runner including carb  that seems to be resonant
around 6200 RPM. (Max torque.) This seems to indicate that it is the first harmonic.

To the numbers in this torque chart from Mazda you must add the fixed
length of 16 inches. That would make the 6500 RPM lenght number 23 inches.

Paul Lamar

The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site. http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.