is there a two stroke engine that will compare in power to a o.s. 300 twin four stroke? i mean like if you had the 300 twin on an airplane and wanted to replace it with a two stroke. thanks in advance.

Maybe one of the big Supertigre engines, I think it is a 4350(?) but it doesn't have as much displacement as the twin. Why not go with a gas engine if you need something that big.

dont know anything about gas.

The OS BX1 3500 (first two pics) the Magnum 1.80 (third pic)
or the S.T. 3000.(not pictured) will fill the bill.

And do not forget the Moki 2.10. This engine makes around 5 horsepower. You might want to look into a gas powerplant like the DA50, Brison 3.2, ZDZ50, or BME 50 instead. The fuel cost would be quite abit lower than a large glow engine with more power also. Here is the DA 50R from Desert Aircraft.

thanks to everyone for all the suggestions. i think i will go with either the moki 2.10 or maybe a gas engine.