FX Engines K303 .21 3-Port Off-Road Tuned Nitro Engine Combo w/2169 Exhaust Pipe

Proven Nitro Racing Performance

Built for serious 1/8 off-road competition, the FX Engines K303 .21 Tuned Nitro Engine Combo with 2169 exhaust delivers explosive yet controllable power across the entire RPM range. With championship-proven engineering, precision internals, and race-optimized airflow, it’s designed to give drivers sharper response, stronger acceleration, and consistent performance when every second on track counts.

About the FX K303 Engine

Race Proven Power

The FX K303 .21 Tuned delivers strong low-end torque and aggressive midrange power, making it ideal for 1/8 buggy and truggy racing on medium to high-traction tracks. The 3-port sleeve works with the included 2169 exhaust pipe to improve scavenging and exhaust flow, helping the engine maintain clean, responsive power all the way to high RPM. The result is a wide, usable powerband with race-proven consistency.

Precision Engine Design

Built around a DLC-coated, tungsten-balanced crankshaft and a precision-lapped piston and sleeve, the K303 is engineered for sharp throttle response and smooth internal efficiency. The 6.5 mm venturi carburetor with a short needle allows precise fuel control, delivering instant throttle pickup and predictable tuning. Every component is matched for tight tolerances to maximize performance under load.

Consistent Track Performance

A lightweight 9-rib cooling head, optimized combustion chamber, and high-quality Japanese bearings keep temperatures stable and reduce wear during long mains. The black-coated crankcase and rear cover improve internal flow while enhancing durability under race stress. Combined with the FX X3 glow plug and tuned exhaust system, the engine maintains stable combustion and reliable power run after run.

Features:

• 3-port sleeve design for strong low-end and midrange power
• DLC-coated, tungsten-balanced crankshaft for smooth, stable rotation
• Precision lapped piston and sleeve for faster break-in and tight sealing
• Black-coated crankcase for improved fuel flow and reduced turbulence
• 6.5 mm venturi carburetor with short needle for precise throttle control
• High-quality Japanese front and rear ball bearings for durability
• Lightweight 9-rib cooling head for efficient heat management
• Optimized combustion chamber with O-ring sealing for stable combustion
• FX X3 glow plug for reliable ignition and consistent performance
• 2169 tuned exhaust pipe for improved flow and stronger power delivery