|
Hi Steve,
A number of possibilities exits regarding timing of
arrival of pulse and port openings/closings.
1st it makes a difference whether you are talking about a
Renesis engine or one of the older 13Bs.
On the older 13Bs (I did the math for it), Mazda timed the
pulse to arrive at the adjacent rotor just as the intake port was closing.
They took advantage of the fact that the combustion chamber still retained some
pressure (even after the exhaust event).
When the intake port of one rotor initially opened, this
retained exhaust gas burst forth into the intake creating a Finite Amplitude
Wave of considerable magnitude. This shock wave (not the air molecules)
was timed to travel through the co-joined intake tubes to arrive at the
second rotor just as it was closing.
When the wave arrived at the speed of sound at the closing
intake port of the second rotor - it created a short duration but large increase
in intake manifold pressure just as the rotor was coming up on its compression
stroke. As you know reversion happens as the upcoming rotor (piston) is on
its compression stroke and some of the mixture already drawn into the combustion
chamber is normally pushed out before the port closes. This reversion
typically is around 15-20% of the amount already drawn into the
chamber.
So the high pressure created by the FAW pulse as it
terminates in the port area reduces or eliminates the reversion effect - with
the end result the chamber retaining 15-20% more mixture and therefore power
than it would normally have. Provided your intake length and rpm are
calculated properly of course.
The Renesis naturally has no overlap between exhaust and
intake port and therefore can not avail itself of the power pulse created by the
exhaust gas bursting into the intake port. However, the pulse is created
in other ways as well and while not quite as powerful, does the job. When
an intake port suddenly closes, it creates a FAW pulse. When that pulse
hits an open or closed area a portion of energy is reflected back (amount
depends in part on amount of cross area change to its route of travel).
When a port suddenly opens also creates a refraction (negative) pulse which can
also be used. The pulse can be timed to arrive at other intake events than
just the closing such as the opening of a port to help "push" more air into the
chamber and as mentioned above to assist in reducing reversion.
Dennis has done the math and his intake reflects
substantially increased performance over his old intake. But, he'll have
to provide the math and timing for the Renesis.
Good luck
Ed
Sent: Saturday, January 01, 2011 8:16 AM
Subject: [FlyRotary] Intake manifold for 4 port
Renesis
Happy New year everyone.
I
noted Dennis Haverlah had re worked his intake and I wondered who on the list
has done the math.
I've done it myself using Mark Warners "Street Rotary",
however I don't know enough about when the reflected wave should arrive
optimally at the open port of the next rotor intake event?
Should it arrive when the port is at its most open state
or latter?
Also, can someone explain to me the timing in degrees of
E-shalf rotation between TDC and BDC (sorry if that is a dumb
question).
Many thanks again to all on the list.
Steve Izett
Perth, Western Australia
The contents of this email are confidential
and intended only for the named recipients of this e-mail. If you have received
this e-mail in error, you are hereby notified that any use, reproduction,
disclosure or distribution or the information contained in this e-mail is
prohibited. Please notify the sender immediately and then delete/destroy the
e-mail and any printed copies. All liability for viruses is excluded to the
fullest extent of the law.
|