>>  > Do the home made butterflies need bearings, seals,

return

springs,

 >>  > throttle position sensors? Am I making this too

complicated?   Jerry

 >>
 >>  You don't need throttle position but some small SS

shielded

flange

 >>  ball bearings would be nice. You can get these from:
 >>  W.M. Berg
 >>  Stock Drive Products
 >>  Sterling Instruments.
 >>
 >>  I think I have some quarter inch versions lying around I

can

send

 >>  you.
 >>
 >>  Paul Lamar

 >>  Looks like the same bearing used in roller blade wheels.
 >>
 >>  T. Webber
 >
 >Godd source :-)
 >
 >Paul Lamar

 OK.  I will take a shot at making the butterflies.   One

last

thing:

 in the drawing you sent of the Everett Hatch Style  ports,

the

bore

 of the section that is inserted is less than the bore that

contains

 the butterfly.  Is this necessary?  What is the smaller

bore?

 Could one use a 2" o.d. x 1.75" bore for the whole thing?

Jerry

Not clear form the drawing put the part than goes in the

housing

is square.

You would not get as much power as the Leman engine.
But if that is OK go for the 1.75" bore. If it were me I would

go

for a two inch bore and 2.25 OD tubeing. Why mess around? You

are

going to cut holes in rotor housings anyway.
Are you going to start with new housings?

The area differnce is:

A 1.75 inch bore = 2.4 square inches.
While a 2 inch bore would be 3.14 square inches.

30% more area.

Paul Lamar

Jerry Hey wrote:

How does bore size relate to fuel consumption, idle smoothness

and

so on.? Can hp at 6000 rpm be predicted for various bore sizes?

I have no idea. We can test for some of those things on the dyno
when you get it built.

Paul Lamar

What if you used the P-Port and Side ports together.  Make the

P-Port

open at higher RPM, Say 4500.  Below that use only the side ports.

Just

a thought.  Also I'm thinking single rotor.
This would increase the volume at higher rpms.  Normally aspirate

no

turbo.  The exhaust port would need to be opened up to increase

the

purging of exhaust gas.  Of course maybe there just isn't enough

room

for both.   Just thinking out loud.  anyone toy with this idea

before?

Tom Webber.

Tom,
I posted a note on this last week.  I have decided to use a PPort

and

center side port together but with separate throttle assemblies.

The

idea/hope is that the idle quality using just the center side ports

will

be more stable than a PPort idle.  By using separate throttles, idle

and

WOT can be controlled separately (idle just using the side ports,

WOT

using both PP and side port).  Note that Tracy used separate

throttle

assemblies on his engine that used motorcycle carbs.  I will test

this

when I can get my work life under control and have time to build
airplanes again.

Ken Powell

Sounds good,  I've been in contact with Rob from Pineapple Racing in
Oregon and he seems to think that a single rotor with both side ports
and a pport would be a lot of area.
I agree with the stable idle using the side ports and devising some
throttle linkage to bring the pport on line after 4000 rpm or so.

Tom Webber

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