January, 2021

Over the past 20 years, most small recreational hovercraft have moved away from two stroke engines to the more economical four stroke alternatives.

From the early days of Viper Hovercraft, I have used four stroke engines such as the Jabiru 2200, avoided the common industrial engines and have always wanted to use the Subaru. I was never particularly pleased with the power output of the early EA series, but liked the high torque, low engine speed and long engine life. The engine is also smaller compared to inline four cylinder engines and has a lower center of gravity.

For the new 5XS series, I am using the Phase 2 normally aspirated SOHC 2L EJ engine series. These engines are fully remanufactured and range from 125hp to 140hp. I have settled on the 125hp version for the 5XS and rescue versions, and the 140hp for the 5XRS. I have reserved a DOHC 165hp version for something special down the track.

The EJ engine is well known for being a long lasting the engine if serviced regularly. It is not a high revving engine and has solid torque right through the engine RPM range. There is no lag in throttle response between idle and max 5,600 rpm. With a average cruise RPM between 3,200 to 4,000, we expect the engine will last at least 2000 hours, and longer if used responsibly.

Fitting a engine that is twice the weight of its predecessor required alterations to the design. The engine is placed further forward and associated items positioned to maximize cockpit space. It has a new lighter hull and duct, light weight drive system, exhaust system and alloy radiator.

The overall look of the V5 has not changed greatly other than the new look engine cover. To maximize seating for 5 persons, I have incorporated a bench seat behind the center seat. This provides more seating area compared to the pervious model even though the cockpit is slightly smaller. The storage compartment space remains unchanged.

To ensure the 5XS performs well, besides keeping the weight low, I have kept the fan duct intake clean. A redesigned fan duct reduced noise, increased lift and thrust efficiency. The extra 25hp is noticeable compared to the previous 5X model. There is more thrust, no vibration and less noise. The 5XS average fuel burn is 9L per/hr compared to 13L per/hr for the previous model.