This email is to address Scott Gettings wanting to know if anyone
else has a set-up like his Renesis 6 port.  I have the same set-up as
Scott, and I'm using only the four yellow injectors and have the two
red ones blocked off, as per Tracy's direction.


However Scott, I cannot get over 5900 rpm. The engine rpm does not
increase after half throttle.  I checked to make sure the throttle
body was opening all the way, and it is. I also removed my muffler
and replace it with a straight pipe thinking there might be an
restriction, not the case, made no difference in rpm.  I chopped my
three blade 76" prop down to 68" and still no change in rpm. I'm also
using part of the original six port intake, with no runner length.
Now the only thing I can think of is the engine cannot get enough
air.  Looks like I have no choice but to completely redo my intake or
try installing a super charger to force more air in.  Not sure if
that will work or not. I'm using Tracy's EC3, EM2, & 2.87 PSRU.

Bob Forbes


The intake configuration and pipe length are critical for the HP.

The prop runs into a brick wall when the tips get close to Mach One.
What is your gear box ratio? Sounds like 2.2:1.   A 3.12:1 would work
better with the rotary.

When the prop torque requirements meets the torque out of the gear
box the prop  and engine of course will stop increasing in RPM.

You can move peak torque around with intake pipe length. You need
roughly 18 to 20 inches of intake pipe length. The longer the pipe
length the lower the torque peak RPM.

A p-port engine will increase the max torque at any pipe lenght.

So too will NOS :-) This is probably the cheapest and quickest. Makes
up for a lot of intake configuration errors :-)

A turbo charger is more economical than a super charger as it uses
the otherwise waste energy in the exhaust to super charge the
engine.

Paul Lamar

Bob please read this section of the web site.

http://www.rotaryeng.net/intake.html

Paul Lamar


Thanks for Bobs output. Questions I have include what is  the prop
pitch and the  throttle body diameter? Is this static or in-flight
RPM? I agree the gear ratio maybe also an issue.

I also have built a short and compact intake system (sounds like
yours) with possible nitrous back up for take off if necessary.  I
will test the entire engine system  mounted in an airboat prior to
flight, which should give me some good data for this pusher
configuration.

Thanks!

Scott Gettings.

Attached are a few pictures of my short intake manifold. I certainly
realize this may not result and anywhere near Optimal horsepower,
but it was simple to build. The throttlebody is 2 7/8 inches inside
diameter.   Although shorter, it is still much less restrictive than
the stock intake manifold system. It can also receive ram air from
the cowl intake. If this does not produce enough power in testing, I
will convert to the over-the-top runners configuration.

Of course, this is not an endorsement of this solution compared to
the longer runners, as Paul has an incredible depth of experience in
this area.

Scott Gettings



Another possibility is that you are over driving the prop. When this
happens the blades stall and creat drag. You, in this case can hear
a definite change in prop noise.

If this is the case and you are satisfied with your prop,as it is, on take
off, slowly advance the throttle. As the craft accelerates the angle of
attack of the blades changes and more power is able to be absorbed
as you continue to advance the throttle.

Rich. Goldman (Been there)

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