Losi – Nitrotec R21 .21 Race Engine.
Developed with the racer in mind, the Italian-made Nitrotec 3.5cc/.21C.I Race Engine was designed to produce a race winning power band and throttle response while delivering exceptional run time. The Nitrotec R21 is recommended for use with the 8IGHT family of vehicles, as well as any nitro vehicle that requires a .21 engine.
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Displacement: .21 cu inches (3.5 cc)
Bore: .6402 inches (16.26mm)
Stroke: .6614 inches (16.8mm)
Practical RPM: 5,000-35,000
Weight (w/o Muffler): 13.5oz (383 g)
Source: www.losi.com