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Hi Joe,
Each chamber has a secondary and a primary port (six ports
have an auxiliary port which is like an additional secondary port). Even
thought a chamber has a primary and secondary, the primary and secondary for a
port normally have different intake timing. Additionally, the
opening of the intake port generally generates a very strong pulse (residue
exhaust gas bursting out of the intake when it opens). Since the
intake and secondary port of each rotor are 60 deg out of phase timing wise with
the other rotor, the pulse generated by each port can interfere or assist with
intake airflow (depending on rpm, manifold air temp, density, etc).
I personally prefer to keep the intake ports separate to
preclude interference. Having said that - I have successfully flow
with a system that combined the secondary intakes and primary intakes, so what
you propose can be done. However, after trying six different intake
configurations, I have found though that I get the best performance (for
our rpm) with 4 separate tubes feeding the throttle body. Keeping in mind
I have a "Plugs Up" installation which generally gives me a bit more room in
running intake tubes. Other arrangements have been tired and
certainly work, so this is no magic formula - just based on my
personal experience.
Yes, the tuning (length) of the tubes should be determined
by the rpm band that you want the most airflow enhancement. It appears
that a tube length from block to Throttle body between 17 and 21" generally
gives good results. Also, avoid excessive large
tubes diameters as intake air velocity is important in stuffing
the chambers and larger tubes results in less velocity. I found
that 1.25" dia tubes for the primary and 1.5" dia tubes for the secondary works
well.
I originally had my intakes merged into a two runner Weber
style manifold. A two port Weber style throttle body with two 2" dia
intakes. While this was the cats' meow for a racer turning 9000+ rpm, it
turned out to be disappointing in aircraft use with lower 5000-6000
rpm. When I replace this "racers'" set up with 4 smaller dia tubes
my ROC increased by 300 fpm immediately. Unfortunately my original
fuel injection system died and I did not get to collect further data
on my old six port 1986 engine before deciding to switch to a 91 turbo
block.
Hope this helps.
Ed
1----- Original Message -----
Sent: Thursday, July 27, 2006 9:24
PM
Subject: [FlyRotary] Intake design
101
I am using a 89 block for mock up and maybe
rebuild. Looking at the intake ports, there are two ports at the front
and rear of the block then there are two rectangular ports in the center
housing close to each other. Others have fabricated intakes using 4
tubes. I assume it is OK for the two outboard front and rear of block to be
fed by one tube while the center two ports need to be fed individually. Is
this correct? The length of the tubes is determined by where on the rpm
vs Hp band you want to operate at? Thanks
Joe Berki
Limo EZ
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