FX K303 Tuned 1/8th off-road nitro engine

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The following press release is from FX Engines:

The FX K303 Tuned is a high-performance .21 competition engine designed for 1/8 buggy and truggy racing. It delivers strong power from low-end torque all the way to high RPM, while remaining highly controllable and easy to handle. This allows for precise power delivery and maximum control on a wide variety of track conditions.

Featuring a 3-port sleeve, a DLC-coated tungsten-balanced crankshaft, and a precision-lapped piston and sleeve set, the engine ensures sharp throttle response, maximum efficiency under racing conditions, and consistent, race-winning performance. A multiple European Championship winner, the FX K303 Tuned has proven itself on the world’s most demanding tracks.

Optimized Flow. Maximum Power.

The black-coated crankcase is engineered for optimized fuel flow, delivering strong power from low-end torque all the way to high RPM.

Refined internal passages reduce turbulence and ensure consistent fuel delivery for precise throttle control and stable performance on medium to high traction tracks.

The updated rear bearing improves durability and long-term reliability under demanding racing conditions.

Result: improved performance and better throttle control.

Maximum Cooling. Consistent Performance.

The lightweight 9-rib cooling head is designed for a low center of gravity, keeping temperatures under control even during long, demanding finals. Optimized airflow ensures consistent cooling at high speeds and in tight technical sections.

Precision machining, optimized geometry, and the clean, premium FX design provide efficient heat dissipation and consistent power delivery throughout the run.

Result: stable temperatures and more consistent lap times.

Stable Combustion. Consistent Power.

The precision-machined combustion chamber ensures a perfect seal and efficient heat transfer, keeping engine temperatures stable under demanding race conditions.

The integrated O-ring design prevents dirt and debris from reaching critical sealing areas while reducing vibrations, ensuring consistent combustion and stable engine performance.

Result: consistent power delivery, improved efficiency, and reliable performance throughout long finals.

The Highest-performance Connecting Rod.

The highest-performance connecting rod, manufactured using advanced FX technology.

Reduced Friction. Maximum Power Transfer.

The K303 Tuned crankshaft features a friction-reducing DLC coating and dual tungsten balancing for superior rotational stability.

The DLC coating minimizes friction and ensures smoother operation of the connecting rod, improves internal flow, and increases the lifespan of the conrod and bearings.

At high RPM, the optimized balance delivers stable engine operation and consistent performance under demanding racing conditions.

Result: maximum power transfer, reduced wear, and long-lasting & reliable performance at any RPM.

Optimized Flow. Smoother Engine Response.

The black-coated rear back plate is precision-shaped to reduce internal drag and turbulence.

Optimized flow improves crankshaft support and ensures smoother, more efficient rotation.

The result is faster throttle response and more consistent power delivery across the entire RPM range.

Instant Throttle Response. Precise Fuel Control.

The K303 Tuned black-coated carburetor features a short needle and optimized venturi for precise fuel metering and stable tuning.

The result is instant throttle response and clean, predictable power delivery.

Strong midrange power and smooth transitions ensure excellent drivability on medium-to-high traction tracks.

Result: faster response, smoother control, and more confidence on throttle.

Precision Fit. Maximum Efficiency.

Each piston and sleeve pair is individually hand-lapped for perfect sealing, faster break-in, and consistent performance.

The optimized 3-port sleeve design delivers strong low-end torque and aggressive midrange acceleration.

The result is smooth, predictable power delivery and reliable performance under racing conditions.

Result: faster break-in, longer performance stability, and consistent power run after run.

Features:

• Excellent low RPM torque & more aggressive midrange power for tracks with medium to high traction conditions
• Black coated crankcase
• Black coated rear cover
• 3 ports+ exhaust
• Bore 16.4 mm
• DLC coated crankshaft
• 2x tungsten balanced crankshaft
• Rear ball-bearing – japan
• Front ball-bearing – japan
• Specially selected & matched sleeve / piston set
• Individually lapped sleeve/piston for easier & faster break-in
• 9 ribs engine head
• Buggy carburetor with short needle – black coated

Specifications:

Displacement	3.5cc
Bore	16.40 mm
Bore	16.40 mm
Weight	349g
Max Power	2.65HP @ 34.000 RPM
Practical Range	4.000~42.000RPM
Ports	3 transfer ports 1 exhaust
Piston (silicium)	Yes
Sleeve (brass, hard chrome plated)	Yes
Combustion Chamber O-ring	Yes
Front Ball Bearing	7x19mm – Steel – Japan
Rear Ball Bearing	14×25.8mm – Steel – Japan
Crankshaft » Diameter » Surface treatment » Balanced	14 mm DLC (diamond coating) X
Carburetor (alloy body, thermal isolation)	Yes
Carburetor Needles	3
Glowplug Type	X3
Exhaust Position	Rear