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From the opening of the intake port (inside the engine) to
the center of my throttle body my intake length is 22". It appears that a
length between 17-24" is workable and gives good results. Tracy use a
similar approach (from which I stole a lot of ideas) and also got excellent
results when he was flying a 13B.
Since I use the stock cast lower and part of the upper
cast (which I cut the cast tubes off and install my own light weight tubes) the
actually length of my tubes is 7-11 inches (adjustable - tubes inside tubes)
. That is the length between my cut-off upper manifold (the one with the
90 deg bend and cast tubes) and bottom of my throttle body plate. However,
The crucial distance of course is from intake port to throttle body - not how
long the tube portion itself it. I use 1 1/4" dia tubes for
the primary and 1 1/2" dia tubes for the secondary. To make an adjustable
one I have a 1 3/8" dia tube over the 1 1/4 and a 1 5/8" tube over the 1 1/2" -
but of course you don't need to do that.
Too large an intake tube appears to diminish the mixture
velocity and inertia and decrease the amount of mixture stuffed into the
combustion chamber, so while large intake diameters are fine for the 9000+ rpm
racers, they don't appear to offer what we need at the rpm we operate
at.
Here is a photo of my most recent intake and one I have
flow with for 3 years. The blue throttle body mount is make out of a two
part polyurethane casting resin and I use a 65mm Mustang TB. Here is a
photo.
Ed
----- Original Message -----
Sent: Sunday, July 30, 2006 7:52 AM
Subject: [FlyRotary] Re: Back in the
saddle again!
Ed,
You are correct! I
have the 2.85 drive. I scraped the tangential muffler and now using spintech
muffler. I received my velocity stacks last week, so it on to rev "B" intake.
By the way how long are your runners?
Thanks,
Jason
From: Rotary
motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Saturday, July 29, 2006 4:56
PM
To: Rotary motors in
aircraft
Subject: [FlyRotary]
Re: Back in the saddle again!
Jason, if I recall correctly you
do have the 2.85 gear box. You should be seeing 5800-6000 rpm
static (perhaps a bit less in that heat). I however do not recall your
prop set up but if it is close to the 74x88 prop Tracy and I both fly with our
2.85 then it would appear your are not getting adequate airflow into( or out
of) the engine.
----- Original Message -----
Sent:
Saturday, July 29, 2006 9:13 AM
Subject:
[FlyRotary] Back in the saddle again!
Update on my airplane, I now
have four flights on my engine after replacing the seals. Last night I was
up for an hour. At 5000msl it was 28C temps stabilized at 197(water) and 188
oil. I still need more power. I am only getting 5000rpm static which makes
for very shallow climb outs. In the air, I'm getting between 5500 and 6000
rpm at about 140mph (no wheel pants or fairings).
I did an experiment with a 12"
fan mounted behind the radiator. The fan keeps the water temp under 190 on
the ground, but caused about a 10-15 degree increase in the air. So now I'm
thinking about mounting a small radiator with a fan under the engine.
My next project is to rework the
intake for more static rpm.
Jason (waiting for winter or at
least temps below 90
degrees)
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