Tell me:
your engine HP at X RPM sealevel

redrive ratio

cruise RPM, and desired cruise speed at that RPM

number of blades, 2 or 3 (probably 3)

prop diameter (limited by rotation angle on a pusher)

> called Tracy and picked his brains A summary of our conversation
> follows:
> > > Drive bushing dia: 5/8
> Drive bushing depth: 9/16
> Pilot boss Dia: 2.25
> Pilot boss depth: 1/2 (I measured this at 3/16 but Tracy advised me
> to allow
> a little extra and specify 1/2
> Bolt Circle Dia: 4.75 (SAE 2)
> > > We discussed the other specifications and my requirements. Tracy
> agreed that
> a 3 blade was the obvious choice. I want best possible cruise, so
> Tracy
> recommended a Max prop RPM of 2850 and a cruise rpm of 2500. This
> will run
> the engine at around 6100 and 5450 respectively. He says that above
> 6100 the
> power rises in a linier fashion while stress on the components
> rises
> logarithmically. I'll be able to "dial in the power I want" by
> adjusting the
> turbo boost. The calculations of max power were interesting. Tracy
> asked my
> maximum boost and, following what I remember about Greg Richter's
> installation, I said 7 - 8 PSI. This is half an atmosphere and,
> apparently,
> power rises in direct proportion to boost. So, if I have a 200HP
> engine
> boosted at 1.5 atmospheres, I should get 300HP which aligns with
> Gregs
> numbers. This assumes no power lose due to intake temp rise and
> exhaust back
> pressure. Allowing 5% or so for looses due to these issues Tracy
> estimated
> 280 HP as a reasonable target. Next came the question of speeds and
> altitudes. After some discussion and considering the norm for the
> Cozy IV we
> ended up at a target of 220 MPH at sea level which would give much
> higher
> TAS at optimum cruise altitude of 12,500.
> > I called Greg Richter and ran Tracy's numbers by him. He agreed that
> they
> seemed reasonable based on his experience with his turbo 13B Cozy
> III, and
> mentioned that he's also planning on getting a prop from
> performance.
> > Performance were very quick. I had the prop in about 3 weeks. Clark
> Lydick
> settled on a 68 diameter, 84 pitch prop, so I'm a bit puzzled that
> it
> measures 33 1/8 from center to blade tip. Anyway, I started fitting
> the
> spinner by copying the curves of the prop with one of those metal
> things
> with pins that move in and out. I transferred the curve to the prop
> and cut
> out the shapes with a dremel. The carbon fiber is fairly flexible. I
> think I
> could have got away with cutting both curves and bending the spinner
> as it
> went on the prop. This way I could have got a better fit. Later
> Clark
> confirmed that my prop is a 66 x 84 with a blade area of 312.3. "

I can work up some numbers for you to build to, blade pitch and chord.

Perry