I just test run my new TH 75 and here is what I used:

Prop: Master Airscrew Scimitar 11x7
glow plug: the plug that comes with the engine, I don't know the brand.
fuel: Homebrew 80/20 castor oil 0% nitro


After about a tank I got a steady 14300- 14600 RPM without sagging and in the rich side with plenty of oil and smoke coming from the exhaust.

I hope this engine gets better with more run time.

So far I'm very impressed and very happy with it!!


Does anyone have readings with the same prop?

Jorge

Shoot I used to have a spreadsheet but lost some info. I have the TH-75 and I want to say I got similar RPM's with a similar set-up (5% Nitro, APC prop.) but I cannot be sure.

The engine seems to like the 12x7 APC so I am running that on a 20+ year old Supra Fly-45. [)]

I'm getting right now 13700 on a 12x6 mas scimitar propeller....it makes me think that the engine likes a heavier prop...I have an apc 12x6 that I may try tomorrow..and maybe I should try a 12x7 or 12x8... I don't like the fact that with the 12x6 the engine (or the plane) cannot be set in a low speed setting...the engine at 1/3 throttle still screams...so it's hard to get the desired airspeed for landing...

Jorge

Try a 13x6 as recommended by the manufacturer. This will lower the revs a little and at 1/3 throttle will be more manageable.

I think if you do a search that you will find an existing tachometer thread featuring this engine. This should shorten your search for the right props. The engine likes RPMs and seems to like the 12x6 for sport and a 12x8 for speedier planes.

Has anyone rpm figures on different props for this engine??

I'ts kind of expensive testing on this size of props....

Thanks!

Jorge