New from HPI Racing, the Nitro Star K4.6 engine, capable of propelling the Savage monster truck to speeds of 44 mph and wheelie off the line. The K4.6 is a 4.6cc (.28 cubic inch) big block engine that features a machined billet aluminum heatsink head for extra cooling, dual bushing aluminum connecting rod, true ABC chrome sleeve construction for durability, and a three needle 8.5mm slide carburetor with a composite body for better performance at higher temperatures. The carburetor features a factory re-set line on the high speed needle and "flushed" needles that make re-setting the carb to the baseline factory specifications quick and easy. This powerful new engine has 10% more displacement than our Nitro Star S-25 engine and is rated at 2.9 horsepower! This is a direct bolt-in replacement for the 21BB and S-25 engines; we recommend 17/47 gearing to prevent excessive wheelies. A pullstarter is standard equipment, and the K4.6 is compatible with the #87126 Roto Start System and #87127 Roto Start Backplate.