Subaru has added a new line of electronic fuel injection (EFI) engines for applications such as generators and lawnmowers. The line includes two models, the EH72 V-Twin and EH72 UTV, both of which it says were designed to reduce fuel consumption and emissions, while providing fast, easy starts in a wide range of ambient temperatures.
Used in car engines since the 1980s, EFI technology allows engines to run on an open-loop system via an electronic control unit (ECU). The ECU takes advantage of several different sensors that measure manifold pressure, ambient temperature, and throttle position. That information is constantly relayed to the injector so it can deliver the proper air-to-fuel ratio and always run at an optimal level. Allowing for differences in operating speed, applications, and fuel type, Subaru estimates that fuel economy improvements are 11 to 25% over that of a similar carbureted engine. Exhaust emissions are reduced by over 20%.
Easier starts are another advantage of the EFI engines. Fuel volume is closely controlled to provide fast starts in a variety of ambient temperatures. The response and acceleration delivered during initial start-up eliminates the need for a choke.
Altitude changes do not effect the EFI engine’s operation due to precise oxygen level detection from the ECU. The system identifies changes in altitude and instantly adjusts the air-to-fuel ratio for the current location. Maximum fuel economy and power in any altitude are achieved throughout the entire power range from low idle to full power, says Subaru.
Both models are available in a 653- or 720-cm3 configuration, with power outputs ranging from 20 to 27 hp (15 to 20 kW). The engines feature a two-barrel manifold with one fuel injector per cylinder. That feature allows each cylinder to operate independently of the other, aiding in fuel optimization and also in improving the engine’s efficiency and performance.
For applications that require a smaller, more compact engine, the EH72 UTV engine is available in a low-profile design for both displacement configurations.
The engines are also available in non-EFI carbureted versions. Similar to the EFI engines, the carbureted versions utilize independently operating cylinders for fuel optimization and improved engine efficiency and performance.