Dave,
I have an APC 17X 10 on my 140DZ now and it peaks out at around 8,450. I run it at 8,300. I tried a Mezjlik 18x6 and it ran up to 9,300. I prefer to use Mezjlik and the largest diameter lowest pitch that works, but I remember reading that you recommend keeping the 140DZ at 8 - 8,500. Would a Mezjlik 18x8 put it in the preferred range? Its running on Wildcat 30% Heli fuel. Since the manual shows a practical range of 7,800 to 9,000, what happens over 9,000 - do the valves float?

Thanks

It depends on the application. Running over 9000 won't hurt it unless you do a vertical down line at full throttle, then you might float the valves. Not many guys ever run them like that, though.

Ya, I'm not likely to do that either! So are you saying I'd be ok to use the Mezjlik 18x6 with good throttle management - or would I be better off to go to the 18x8? The application is sport aerobatics with mild 3D.

Thanks

I think the vertical will be better with the 18x6, but try both and see.