Date: Sun, 31 Jan 1999 01:07:21 -0800
From: Paul <rotaryeng@earthlink.net>
To: z <rotaryeng@earthlink.net>
Subject: Dynamic Chamber Intake manifolds
Tracy Crook wrote:
snip........
Everett was talking about air speed velocity, not pressure wave speed.
I
don't have my references handy but the energy of the pressure wave
(generated by the closing of the intake port) is going to be
proportional to
to the square of the velocity (V) in the intake runner (E = 1/2 MV
squared). The resultant pressure wave from your 1 mph example would
propagate at the same speed but it would not have enough energy in it
to do
any good. There are so many tuning books stressing the importance of
charge
velocity that I am very surprised by your "bigger is always better"
statement. I have no personal dyno experience but I have witnessed
the
failure of many hot rodder's engine build-ups who followed the bigger
is
better formula.
Also, keep in mind we are talking about side port engines running at
6000
rpms, not Le Mans peripheral port monsters running at 9000. The
single pipe
feeding the peripheral port at these speeds (velocity increases with
speed
of course) could use a significantly larger runner size. If you took
this
to the extreme (i.e., use 55 gal. drum sections for the runners) it
would
not work. I'll take any bet at any odds on this :-)
The object in choosing runner diameter is to achieve the highest
possible
velocity without causing a significant pressure drop below atmospheric
at
the port at bottom dead center. You want the maximum inertia of
intake
charge to keep that air flowing into the chamber.
Paul Lamar wrote:
Will you guys stop screwing around and get some of those
manifolds on the dyno? :-) :-)
Hey! this debate started over Everetts dyno testing results. You
already
admitted that he got more horsepower at 6000 rpm than anyone else.
Don't
you think he would have used 2 inch pipes instead of those tiny
looking 1.5
inchers if bigger were better?
Tracy Crook rws@altavista.net
Everett was wrong! He could have had a lot more.
OK guys here it is! Read it and weep. The HP chart for the Mazda Le Mans
engine.
360 KW at 6000 RPM,at 746 watts per HP, is 482 HP for a four rotor.
Half of that for a two rotor is 241 HP!!!!
That's with roughly a two inch sewer pipe intake manifold about 24
inches
long at ONLY 6000 RPM!
OK guys wiggle out of this if you can :-)
Lets get on with it. Build your best shot and let Paul Yaw
test it on his dyno.
When the flag drops the bull shit stops :-)
Surely we can get 200 HP with a ported six port side port at 6000 RPM.
Paul Lamar
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