O.S. MAX R21 On/Road 1/8 Race Engine
O.S. Engines have introduced their new Speed R21 3.5cc nitro on-road engine.
The power plant is based off of the O.S. R2102, however it is understood the engine received a make-over in various aspects to make it more affordable yet easy to tune
Displacement: 3.49 cc
Bore: 16.08 mm
Stroke: 17.2 mm
Practical RPM range: 4,000-45,000
Output: 2.76 hp @ 33,000 rpm