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I don't think those tubes diameters are going to be a
problem, but 2" dia is too much based on my experience. I have not
experimented with the Log Manifolds, therefore can offer any
suggestions. I know they can be made to work, but I suspect that there are
certain critical factors that must be carefully considered (that's the way it is
with any induction system).
Make certain your are using radiator hose that has a
spring inside or is otherwise strong enough to withstand the almost 14.7 psi
imposed when you close the throttle - else you could suck them flat
{:>). Otherwise, sounds like a cheap and smart way to experiment.
Good luck and keep us all informed
Ed
----- Original Message -----
Sent: Sunday, July 30, 2006 10:07
AM
Subject: [FlyRotary] Re: Back in the
saddle again!
Ed,
I am using 1 ¾
secondary and 1 ½ primary tubes. That is what matched the port size on the
engine (when deformed to the oval shape of the port). The lengths of the
runners are eight inches from the side of the engine. The runners terminate
into a 4" manifold log and a 65 or 70 mm T/B. My plan is to build a new
manifold log with velocity stacks and then experiment with different length
radiator hose for runners. I know this is not optimal for flow but it should
get me in the ballpark quickly. Any suggestions are appreciated.
Thanks,
Jason
From: Rotary
motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Sunday, July 30, 2006 8:04
AM
To: Rotary motors in
aircraft
Subject: [FlyRotary]
Re: Back in the saddle again!
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.
----- 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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