The OS FS-91 Surpass is a legendary, single-cylinder four-stroke nitro glow engine manufactured by O.S. Engines, highly regarded in the RC aircraft community for its reliability, excellent torque, and signature scale sound. First introduced in the late 1980s to replace the older FS-90, it provides roughly 20% more power than its predecessor while weighing less.
Displacement: 0.912 cu in (14.95 cc)
Power Output: 1.60 hp @ 11,000 RPM
Practical RPM Range: 2,000 – 12,000 RPM
Weight: 22.9 oz (650 g)
Valvetrain: Overhead valve (OHV), helix gear-driven front camshaft
Bearings: 4-bearing design (two for crankshaft, two for camshaft)
