O.S. Speed R2104 .21 9-Port On-Road Nitro Engine (Turbo)

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O.S. Speed R2104 .21 9-Port On-Road Nitro Engine (Turbo)
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This is the O.S. Turbo Speed R2104 .21 9-Port On-Road Nitro Engine, a factory tuned engine solely developed for 1/8 racing competition. This redesigned engine boasts 9-port piston liner to improve torque in low-middle power range. It also produces enough power as designed even for high traction tracks. The redesigned crankshaft counter weight enables smooth power transition from low to top. Distance of each fin of the heat sink head is enhanced for better air flow for cooling and better balance. The heat sink head is anodized in both black and red for a high contrast and powerful aesthetic.

 

Features:

  • Cylinder Liner: This engine boasts a 9-port piston liner to improve torque in low-middle power range. It produces enough power as designed even for high traction tracks.
  • Outer Head: Distance between the cooling fins is enhanced for better air flow and better balance. The heat sink head is anodized in two colors: black and red.
  • Inner Head: A silicon O-ring fit to the inner head prevents dust from coming into the engine.
  • Crankshaft: The redesigned crankshaft counter weight enables smooth power transition from low to top.
  • Carburetor: The carburetor is 21M2(B), which has been proved to be consistent and reliable for generations (R2101, 2102, 2103)
Specifications:
Bore: 16.08mm (0.633" )
Carb Type: Slide valve
Crankshaft Threads: UNF 1/4-28
Crankshaft Type: Threaded
Cylinder Type: Nine port liner
Cylinders: Single
Displacement: 3.49 cc (0.213 cu in)
Engine (Only) Weight: 340g (11.99oz)
HP: 2.8 ps / 2.76 hp at 35,000 RPM
Height: 91.2mm (3.6"), total height
Length: 94mm (3.7") backplate to of crankshaft
Plug Type: OS RP7 turbo, cold heat range
RPM Range: 4,000 - 45,000
Recommended Fuel: 10 - 30% nitro content, 20% recommended for break-in
Starter Type: Bump
Stroke: 17.20mm (0.677" )
Type: 1/8 scale buggy engine
Width: 45mm (1.8") at mounting tabs 

This product was added to our catalog on December 10, 2019

D.K.
Saturday, Apr 20 2024 (6 months ago)
O.S. Speed R2104 .21 9-Port On-Road Nitro Engine (Turbo)
The nitty gritty: It's an O.S. - Nuff' said.

Got this at my local hobbyshop along with a Kyosho GT3 competition kit. Not finished breaking it in yet, I am finding it hard to make it to full throttle now that I am down to the last 3 tanks, even just to touch the top end.

I Would estimate the car is doing 60 mph at approximately 60% throttle. Excellent response, easy tunning.

One tip is to use a caliper depth gauge and seth the mid speed screw depth to 0.10mm, measuring from the inside of the head slot to the flat part of the carb and set your idle gap at 0.5mm in width after breaking in the motor. This will make it significantly easier to tune.
Daytona
Monday, Feb 19 2024 (8 months ago)
O.S. Speed R2104 .21 9-Port On-Road Nitro Engine (Turbo)
I installed this R2104 combo in
My serpent 1/8 SXR GT TQ - (used the wrap around header) super happy so far with this engine . After 10
tank of fuel -low to mid range power is instant, top end just keeps revving -sound is a incredible high pitch scream -holds its tune well -has never quit or stalled after warm up -zero complaints on this one -also installed optional pinion and spurs - lowest ratios serpent sells -my first OS ,impressive engine-