Abstract: The air/fuel mixture ratio supplied to an internal combustion engine of a vehicle is modified to achieve a constant mass flow rate in spite of changes in atmospheric temperature and pressure conditions by employing an electronic compensation system. The system has sensors which detect air temperature and barometric pressure, from which signals are developed controlling the float bowl pressure in the engine carburettors, thus modifying the air/fuel mixture ratio as desired. The system also includes provision for enriching the fuel content of the mixture supplied to the engine to provide an oversupply of fuel in cold start situations.

Abstract: The invention relates to a variable venturi for a watercraft vehicle or similarly powered vehicle which allows the operator of the vehicle to selectively choose to operate a watercraft vehicle for achieving maximum acceleration or, alternatively, maximum top end speed. The venturi is comprised of a collar surrounding the venturi adjacent to a distal end of the venturi. At such time as the collar is activated, exposing the water flow exiting the venturi to atmospheric pressure, the diameter of the water flow exiting the venturi is reduced by approximately 1.0 mm. to 1.5 mm. in radius. This slight change in the surface area of the water flow provides a lower mass flow of the exiting water with an increased velocity of the water and top speed of the vehicle. Alternatively, a larger diameter venturi provides a higher mass flow with a decreased velocity and maximum acceleration.

Abstract: In an exhaust expansion chamber or tuned pipe of a two-cycle engine in a watercraft, variable amounts of water are injected, thus cooling the temperature within the expansion chamber and matching the sonic wave speed with that of the correct rpm of the motor. Thus, by regulating the temperature of the exhaust gases in the tuned pipe with water, the efficiency of the two-cycle engine at varying revolutions per minute, is improved.