O.S. Engine OSMG2040 21XZ-R On-Road Competition Powerplant  [OSMG2040]

Overview: O.S. Engine 21XZ-R for Serious Racers

The O.S. Engine 21XZ-R On-Road ABC w/21M is targeted at experienced 1/8 on-road pilots looking for a controllable, high-output motor. The tungsten-weighted crankshaft helps stabilise rotational mass, improving tractable power delivery through the rev range for cleaner exits and corner drive.

Design Highlights and Combustion Layout

The cylinder liner arrangement, with seven scavenger ports plus three exhaust ports, is arranged to boost scavenging efficiency and improve combustion. Matched components like the new crankcase and 21M carburetor smooth airflow and fuel metering, while the light piston and sturdy con rod are chosen to cope with repeated racing stresses.

Performance Specs and Practical Use

Measuring 0.284 cubic inches (4.65 cc), the 21XZ-R produces 3.31 hp at 32,000 rpm and operates usefully from about 4,000 to 38,000 rpm. At 13.1 ounces (375 grams), the unit keeps mass down so chassis balance and handling are easier to tune for race setups.

For racers who want predictable midrange torque and a durable build, the O.S. Engine 21XZ-R is a solid choice for 1/8 scale on-road applications where consistency lap after lap matters.