Novarossi KEEP OFF 21-4 Tuned .21 Off Road Engine (Turbo) (Ceramic Rear)

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This is the Novarossi KEEP OFF 21-4 4-Port .21 Competition Off Road Engine. The KEEP OFF includes all the tricks and tweaks that Novarossi has developed for their off-road engines, most notably a unique and patented bearing design that reduces the inertia of the rotating mass and increases the engines scavenging, delivering increased throttle response and higher top speed. This, combined with a factory tuned crankshaft, and 4-port sleeve deliver the best combination of linear power delivery and minimal fuel consumption possible. Additionally, the Evolution 2 cooling head was chosen to keep the cooling head mass as low as possible, and the re-designed exhaust gasket helps to increase the life of the gasket.


  • Cooling Head: The 'Lighter & Lower Evolution 2' cooling head has been drilled and milled out to reduce the mass of the cooling head, lowering the Center of Gravity of the engine/car.         
  • Sleeve: The sleeve has 4 transfer ports, the best option to provide linear power with minimal fuel consumption.
  • Crankshaft: This engine is "Factory Tuned" and features a modified crankshaft to further improve the power output and driveability.
  • Gasket: The inner shape of the gasket has been redesigned to allow the use of more material and when combined with an updated material is more resistant to high temperatures.
  • Conrod: The R7 conrod is machined from a super light aluminum that has been checked ultrasonically. The unique shape of the R7 rod creates less turbulence inside the engine.
  • Backplate: The shape of the rear cover helps to optimize the crankcase filling and reduces dead space. The steel plate helps to reduce friction and increases the life of the rod.
  • Carburetor: The plastic carburetor is a "reverse" type with a sliding throttle valve.
  • Rear Ball Bearing: The ceramic rear ball bearing reduces the inertia of the rotating mass and increases the engine's scavenging ability. The bearing, combined with the re-designed case provide increased throttle response and higher top speeds.
Recommended Tuned Pipes: 51006M, 51016, 51020M
Recommended Manifolds: 41021, 41029, 41030

Recommended Glow Plug:
  • C5TGC: For ambient temperature - 32F/50F (0C/10C)
  • C6TGC: For ambient temperature - 50F/77F (10C/25C)
  • C7TGC: For ambient temperature - 77F/104F (25C/40C)
Displacement: 3.49 cc
R.P.M. (max power): 36,000 RPM
Practical Range: 6,000-38,000 R.P.M.
Bore x Stroke: 16.26x16.80 mm
Sleeve: 4 ports
Rear Ball Bearing: ceramic
Front Ball Bearing: steel
Crankshaft: 14 mm - turbo - tuned
Carburetor: plastic - 9 mm - reverse
Glowplug: Turbo (C6TGC)
Exhaust Position: rear
Weight: 360g
Fuel type: 25% nitro

This product was added to our catalog on March 29, 2013.

Daniel Jones
Verified Owner
Monday, Sep 9 2013 (about 3 years ago)
Novarossi KEEP OFF 21-4 Tuned .21 Off Road Engine (Turbo) (Ceramic Rear)
Great engine with a nice bottom end. Not quite the top end that the 7 port engines benefit from but on the tight/complex tracks that I race on it is really very good. I have had no problems running 10 minutes on the NR 2096 pipe and I really recommend this engine for competition use.