Novarossi PLUS.21-4BTT TUNED 4 Port .21 Off Road Engine (Turbo)

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This is the Novarossi PLUS 21-4BTT TUNED 4 Port .21 Off Road Engine. The PLUS.21-4BTT is the evolution of the famous PLUS.21-4C TEAM engine, but with a few tweaks to further improve its potential. The PLUS.21-4BTT features the redesigned 'Lighter & Lower Evo2' cooling head that lowers the center of gravity of the engine and chassis, as well as improving cooling efficiency. The sleeve has been reworked, lowering the fuel consumption and producing more power. The crank spins on a high quality ceramic rear bearing that was selected for improved performance and lifespan, while the backplate has been updated with a steel insert for reduced conrod friction and extended conrod life.


  • Cooling Head: The 'Lighter & Lower evolution 2' type cooling head has been drilled and milled out to reduce the mass of the cooling head, reducing the Center of Gravity of both the engine and car.
  • Compression Rings: The ignition timing is controlled with shims that vary in thickness. You can add or remove a shim to alter the ignition timing. The ignition timing is related to the percentage of Nitro in the fuel and the altitude (above sea level) of your model.
  • Conrod: The R7 conrod is made from a super light aluminum which has been ultrasonically tested. The shape of the R7 rod reduces turbulence inside the engine while running.
  • Sleeve: The sleeve has 4 transfer ports, the best compromise to make linear power with minimal fuel consumption.
  • Rear Cover: The rear cover optimizes case volume and reduces dead space. The steel plate reduces friction and extends the lifespan of the conrod.
  • Crankshaft: This engine has been "Factory Tuned". Novarossi has modified the crankshaft to futher improve the power output and driveability.
  • Rear Ball Bearing: The rear ball bearing has high quality ceramic balls to minimize wear and inertia to improve acceleration and fuel consumption.
  • Carburetor: The carburetor is made from plastic, in "reverse" style and has a sliding throttle valve.
  • Glowplug: The glowplug of engine is a Turbo type glowplug. Turbo glowplugs have a different shape than Standard glowplugs and therefor are not interchange able with engines that are using Standard glowplugs!

Recommended Tuned Pipes: EFRA 9901, EFRA 9853
Recommended Tuned Manifolds: 41021, 41029, 41030

Displacement: 3.5cc
Max Power: 2.60 HP @ 35,500 RPM
Practical Range: 6,000 ~ 38,000 RPM
Bore x Stroke: 16.26mm x 16.80mm
Transfer Ports: 4
Ball Bearings Front: Steel
Ball Bearings Rear: Ceramic
Crankshaft Type: 14mm - TURBO SG
Carburetor Type: 9mm Slide
Material: Plastic
Adjustment: Single
Glowplug Type: TURBO - C6TGC
Exhaust Position: Rear
Fuel Type: Advise; 25% Nitro

This product was added to our catalog on March 2, 2011.

Bjarne Petersson
Monday, Oct 10 2011 (about 5 years ago)
Novarossi PLUS.21-4BTT TUNED 4 Port .21 Off Road Engine (Turbo)

My very good friend just won the Danish National with a BTT engine. His engine has been running +6 races with semis and 45 min a mains in all races. He has only changed the conrod mid summer. Not that it was worn out but for safety. Otherwise its bone stock :-) Novarossi engine are the best on the marked!)
david crank jr
Tuesday, Sep 20 2011 (about 5 years ago)
Novarossi PLUS.21-4BTT TUNED 4 Port .21 Off Road Engine (Turbo)
well plus 4c are easy tuned than 4BTT. but 4BTT are not same tuned like plus 4c. after i break in 4BTT then racing and have to keep low speed rich and top speed lean little it save lasting long life has 5 gal on it temp 230-250 run perfect. i run novarossi 9901 pipe on i like it this 4BTT thank)
matthew fitts
Tuesday, Sep 13 2011 (about 5 years ago)
Novarossi PLUS.21-4BTT TUNED 4 Port .21 Off Road Engine (Turbo)
Any reviews on this motor any better than the plus 4C team edition anyone?)