Hi Kec

First, make sure you email him at the correct email address
[email protected]

Dub was out of town at the NATS last week. He just got back in the shop on Tuesday.

The 76L is designed to run in the 9500-11,000 rpm range.

Typically we fly with 14x4, 14x6 and 13x6 props. But as you surmized, it can run with other props that keep it in that primary power band.

A quick start to this selection is a very simple load estimation dia x dia x dia x pitch = constant (yes, wide blades and blade shape make a difference, but its a good start)
For example :

14*14*14*4=10976 (11,000 rpm - std blade higher rpm limit 14x4W is 10,500 rpm)
13x13x13x6=13182
12*12*12*8=13824
14*14*14*6=14464 (10,000 rpm - typical baseline)
12*12*12*9=15552

This is pretty much consistant with most of the bench tests I have run.

With the lite-muffler, I would suggest a 12x8, maybe pushing the 12x9 after break-in.
With a Turbo-Jett muffler you get a bit more power and torque - the 12x8, 12x9 would do quite well, and Id bet the 12x10 would run ok too. (I may have to try that this weekend)

Image here is a 14x4w with the lite-muffler

I trust this answers your question.

Of note, the control line version of the .76L typically turns a 13x4 or 14x4 3-blade stunt prop

Bob