The Laser 70 may be a bit more powerful than a 52 Surpass; but not by much. The rule of thumb with Lasers is a given displacement is equal in power to the next LOWER displacement of one of the higher-compression Japanese engines.

This is what I was told, anyway. And my several years of experience with a Laser 150 has borne it out; my Laser 150 puts out about the same power as a Jap 1.20 four stroke.

Mine was broken-in with, and has been fed a steady diet of, 15% nitro fuel. Neil Tidey of Laser told me that the nitro wouldn't hurt anything, and would give a slightly smoother, lower rpm idle; but his engines are designed to run on no nitro and do so just fine.

Mine, on 15% fuel, has been without question the most reliable glow engine I've ever owned. I have to adjust the mixture twice a year, when our season changes (we have two; hot, and not quite so hot ).