O.S. Speed R2103 3.5cc nitro on-road engine
O.S. Engines have introduced their new Speed R2103 3.5cc nitro on-road engine. Developed with the forthcoming 2017 IFMAR World Championship in mind, the power plant features a newly designed crankshaft and a new piston and liner. Compared to the R2102 engine the R2103 will offer more low to mid-range torque and this is why the engine comes with a standard steel main bearing as these are meant to further improve torque characteristics.
Source: O.S. Engines [os-engines.co.jp]