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.

Bill

The point you are missing is that the power is way down at 10,000 feet. You
will never get 247hp so VNE is not a problem.( Been there done that) What we
are aiming for is
power at altitude with good economy. Power/speed figures at sea level are
good for hanger talk only.

Ian.

On the other hand the more power you have at sea level the more power
you have at 10,000 feet.

Paul Lamar

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