O.S. SPEED R21GT2 Combo Set (OSMG3001)

OS SPEED R21GT2 Combo Set is a high-performance RC engine package designed for GT-class on-road cars. It preserves the smooth feel and good fuel efficiency of the popular R21GT while sharpening mid- and low-range power, thanks to a redesigned crankshaft counterbalance and a revised inner head that improves idling stability. An O-ring helps dampen vibration and resist dust, and the lighter outer head with machined cooling fins supports better heat management. The combo comes with a tuned silencer and a compatible exhaust manifold for a complete install.

Key details include a crankshaft with tungsten counterweights for balanced performance, a revised inner head that enhances low- and mid-range response, and a lighter outer head for further weight reduction. The engine breathes through five scavenging ports and three exhaust ports to meet racing regulations, and it uses a double-adjust GT carburetor with a 7.0 mm venturi for precise air‑fuel delivery. This combo is designed for GT chassis and delivers reliable idling, smooth throttle response, and steady on-track power.