what would be the energy output of an supre tigre GS45- ABC?

Ibelieve you can search the tachometer reading section and find what people have been getting on their setups. The ST is a common enough engine.

SPECIFICATIONS
Stock Number: SUPG0150
Displacement: 0.46 cu in (7.5 cc)
Practical RPM Range: 2,500-16,000
Output: 1.5 hp @ 16,000 rpm
Weight w/o muffler: 13.2 oz (377 g)
Weight with muffler: 18.5 oz (524 g)
Includes: GS-45 ABC Carb, Silent Muffler .40-.51, Glow Plug
Recommended Props: 9.5x6, 10x6

Those are ST's specs.

Given a 10x6 recommended prop, and a more realistic 13000 RPM max rate, this engine outputs closer to 1.2-1.3bHp under OPTIMUM conditions.

It is generally taken that published power figures have no basis in reality.

Loved this engine....After a proper break-in ... KICKIN'power!!!!

One thread http://www.rcuniverse.com/forum/fb.asp?m=6262131
You can search the tachometer readings forum for more.

so the energy output = engine output?.... just convert it to kw or whatever units i need?

Slightly more than an equivalent sized OS engine, with the trade-off of more fiddly tuning.