<... at 5600... designed for 6300 ... not far off ...>
Drag increases with V^2 so 5600/6300 = .889; .889^2 = .79 so you're under 80% of the way there.
What about a BIIIIG waste gate so you can run WOT with very little boost and then gradually close the waste gate? 
That seems the most efficient way go go ... Jim S.

John Slade wrote:

Are you trying to set max speed cruise at some low rpm like 5000?

Not at 5000. I've already turned it at 5600, and that was without wheel pants. Clark designed it for an rpm of 6300, so I'm not that far off.  The general idea was to optimize for cruise at the expense of take-off and climb. Of course I plan to get it cut back, but I want to get some better numbers with the pants on before sending it back. I'm thinking of getting a 2 blade backup prop based on these numbers before sending the 3 blade back so I wont be grounded for 4-6 weeks.

 

Thanks for all the other input on octane, boost etc. etc.

 

John