The FX K303L Tuned is a high-performance .21 competition engine designed for 1/8 buggy and truggy racing. It delivers exceptionally smooth and linear power from low RPM all the way through the entire power range, providing maximum control and excellent drivability.

The progressive power delivery makes the K303L especially effective on lower-traction and bumpy tracks, where smooth throttle response helps the driver maintain traction and keep the car stable under acceleration.

Featuring a 3-port sleeve, a K303L-specific DLC-coated, silicone-filled and tungsten-balanced crankshaft, and a precision-lapped piston and sleeve set, the engine delivers smooth throttle response, maximum efficiency, and consistent race performance.

The black-coated crankcase is engineered for optimized fuel flow, supporting the smooth and progressive power delivery that defines the K303L.

Refined internal passages reduce turbulence and ensure consistent fuel delivery for precise throttle control and stable performance, especially on lower-traction and bumpy tracks.

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

Result: smooth power delivery, better throttle control, and maximum drivability.

The K303L Tuned black-coated carburetor features a short needle and optimized 6.5mm venturi for precise fuel metering and stable tuning.

The result is smooth, predictable throttle response and progressive power delivery.

Linear transitions from low to mid RPM provide excellent drivability and make the engine easier to control when available traction is limited.

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

The K303L-specific crankshaft is designed to create the smooth and linear power characteristics that distinguish the K303L from conventional racing engines.

Featuring a friction-reducing DLC coating, silicone filling, and dual tungsten balancing, the crankshaft provides excellent rotational stability and exceptionally smooth engine operation.

The optimized design creates a more progressive power curve, allowing the driver to apply throttle smoothly without upsetting the car, especially on lower-traction and bumpy tracks.

Result: linear acceleration, improved traction, maximum control, and reliable performance at any RPM.

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

The optimized 3-port sleeve design works together with the K303L-specific crankshaft to deliver smooth low-end torque and progressive acceleration throughout the RPM range.

The result is smooth, predictable power delivery and excellent drivability under demanding racing conditions.

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

The K303L connecting rod is engineered to withstand extreme loads and high RPM, ensuring reliable operation under the most demanding race conditions.

Manufactured using advanced FX technology and premium materials, it delivers maximum strength, precision, and long-term durability.

The optimized design ensures efficient power transfer and consistent engine performance throughout the run.

Result: reliable performance, stable power delivery, and confidence at high RPM.

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.

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 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.

Each K303L Tuned engine includes the FX X3 glow plug, optimized for reliable ignition and stable combustion.

The carefully selected heat range ensures clean throttle response and consistent performance under demanding race conditions.

The FX glow plug range allows precise tuning of engine characteristics for different track conditions and driving styles.

Each engine is individually hand-finished to deliver consistent performance from break-in through the most demanding race conditions.

Built for reliability. Proven on the track.