3i-684i B4 4-Cylinder long flight gasoline model aircraft engine

High-performance 4-cylinder engine as a twin spark version

A powerful, 6-bearing crankshaft and large ball and needle bearings guarantee a long service life. The engine was basically developed for industrial applications. Both the aircraft and the electronics are protected in the long term thanks to the minimization of vibrations.
The rear crankshaft drive enables the installation of additional devices such as a starter or genera-tor. Decompression valves installed as standard make starting the engine easier. A 1/2″ square in the propeller’s drive plate enables the engine to be started externally.
The TS version (twin spark) impresses with a lower idle and quieter running behaviour. In addition, the boxer engines obtain even greater reliability this way. When one ignition fails, the second one working independently ensures that the engine continues to run.
The microprocessor-controlled ignition enables simple engine control. The programmed ignition curve is exactly matched to the engines and guarantees good running characteristics in all rotation-al-speed ranges. The standard ignition can be operated with a voltage of 6 V up to 8.4 V (2-cell LiPo).

3i-684i B4 Four-Cylinder Gasoline Engine
The 3i-684i B4 is a high-performance four-cylinder gasoline engine designed for professional UAVs and fixed-wing model aircraft.
With precise electronic ignition, optimized air cooling, and a balanced crankshaft design, this engine delivers smooth power output, excellent fuel efficiency, and reliable operation under demanding conditions.
Ideal for long-endurance flights and heavy-lift VTOL applications.