The ST .51 is an outstanding engine. All STs are great engines. HISTORY: When STs were distributed by World Engines (also the distributor of OS) they were the cream of the crop. ST engines were much more rugged than OS. OS was considered the newbie's plug and play toy. In 1985 Great Planes bought the import rights from John Maloney. OS received its fame as a out-of-the-box item while ST required some care as it just got better with age and use. The OS remained a favorite of the newbies coming into RC during those times, because they did not have to do much with them. We older more experienced modelers knew where the real man's machine was and ST was it.

When GP bought ST and moved the production to China from Italy there was a period when the ST was not available. Couple that with so many engines now on the market, and GP, IMO, simply has not been able to return ST to the unlearned market, thus the prices have tumbled. I LIKE THAT.

Once you get a few tanks of fuel through that .51, you will not want to trade it. Dependable. powerful and user friendly and I was flying a Profile thing with one just this day.