I have one of these engines, but am unsure of the best airframe size. It is 14 cc, or 0.82 cubic inches 4 stroke petrol engine. The manual says it make 1.2HP (1000W) on a 13 X 6 prop, generating 2kg thrust. The all up weight (engine, mount, ignition, exhaust, ignition battery) is about 750gm.

The manual says use 'a 0.70 four stoke size aircraft', but adverts for the motor say 'ideal for nearly all 0.40 to 0.50 model planes'. I'd like to mount it in an existing 0.46 (2 stroke) plane (Hangar-9 Mustang PTS), but am unsure if this will work? Alternatively, should I move up to a 60 size plane, like the Hanger-9 Pulse?

A 40- to 50-size model airplane is meant to fly on a .40-.50 cu.in. 2-stroke engine. The equivalent in power is a .70-.80 4-stroke. So the manual and ads are correct by stating

... use 'a 0.70 four stoke size aircraft', but adverts for the motor say 'ideal for nearly all 0.40 to 0.50 model planes'.

Ivan

it works good on the .40 to .50 size airplanes.
if the airplane was designed for a 40 or 46 engine then you can get some sparkling performance out of it by using the Saito 82.
I have the older Saito 80 on one of my planes intended for a .40 to 45 engine. Works good.
Now a .60 trainer type of plane or a scale Piper Cub or something would probably work Ok too, if the kit was intended for the weaker .60 engines.

Thanks for the advice. I ended up getting a Hanger-9 Pulse 60. It was a toss up between the 40 or 60 size.

In the end, I'm glad I didn't go for the 40 size. Everything would have been a squeeze and the engine would have dominated the plane.

The engine fits nicely onto the 60 airframe, although it is 5mm short for the cowling (I guess I will need a prop extender). The ignition module, 100ml fuel tank and 5 cell 6V battery for the ignition, with a wrapping of 5mm foam for each, are a perfect fit for the compartment behind the fire wall.

I've run a few tanks through the engine, using a 13 X 7 prop. It seems to start easily and is running good so far during the break-in period. I'm still a weekend or two away from having the plane ready for the air.

I'm attracted to the petrol engine to save fuel costs. I hope I can use the engine/Pulse 60 as my main plane for the next 6 - 12 months. If so, the engine will pay for itself through fuel savings. It also seems very fuel efficient, compared to a nitro. A 100ml tank at 5000 revs took about 20 minutes to empty. It's pretty clean running too - a slow drip of black oil from the drain opening at the bottom of the plane (1 drop every few minutes) and no visible smoke in the exhaust stream).