Good going Bill. That is just plain great. Here is a tip.
The stock RX8 manifold makes 247 HP at 8500 RPM.

        Actually, it makes 247 HP at 8500 RPM. Peak torque is at 5500 RPM.
The redline (in Japan versions) is 9500 RPM.

You will need a bit shorter
runners to get peak HP at 7500 RPM

        I'm not at all an expert on propellers, but I was thinking about a
three blade to reduce the diameter a bit so I could spin it in the vicinity
of 3000 RPM. With a 2:85 PSRU, this would put me on the peak HP of the
engine. Perhaps I'm missing some key point.

        If you do the math, it becomes obvious that you couldn't cruise at
247 HP in an RV-7. It would put you over the Vne. Thus, you would spend
most of your time with the engine running closer to 7000 RPM, likely even less.

and of course you won't get 247
HP either. HP = RPM X Torque /5252 as I recall.
The other issue is if you remove the rotating sleeve in the
the big end housing ports you will need to use a slightly larger diameter
runner for those ports.

        I intend to leave the sleeve in place. It looks like it is
reasonably aerodynamic. Also, as per my original plan, I hope to emulate
the stock manifold, which would include the secondary port sleeves. The
mechanism that operates these in the RX-8 is compact, so I may make a plate
to accommodate it, if I find that it would be an advantage to operate the
secondary valves at low power settings. Who knows, it might help the fuel
consumption.

Also people will need to do the JB Weld trick
to stream line them. On the other hand It might be possible to cut the
sleeve off and fix it in the port permanently.

        The RX-8 sleeves are already streamlined. I guess the Mazda folks
learned something from the racers. :^)

        Bill Dube'

Did you not get all those pictures I sent? Here they are again.
One RX8 HP curve and two of the sleeves. Check with you ISP.
They may be pulling an AOL.

Mazda backed off the  RX8 HP claims to 238 HP when a bunch of
people started putting RX8's on chaissis dynos. Something to do with
the EPA.

Paul Lamar