Brake Specific Fuel Consumption and Power Advantages for a Turbocharged Two-Stroke Direct-Injected Engine

Abstract

A turbocharged gasoline direct injection (GDI) two-stroke engine for use in snowmobile applications has been developed. Applying GDI to a two-stroke engine significantly reduces emissions of unburned hydrocarbons and improves fuel economy by reducing or eliminating the short-circuiting of fuel that occurs in conventional carbureted two-stroke engines. Performance is a high priority for recreational enthusiasts. Direct-injection also allows for further improvement in power and efficiency through the use of exhaust turbocharging. With the scavenging and fuel flows separated, turbocharging can efficiently increase the mass of air delivered to the engine. This increases specific power output and decreases specific fuel consumption. Results show that the brake specific fuel consumption (BSFC) of the turbocharged engine was improved over the entire engine operating range compared to the naturally aspirated engine. It was seen that a mild boost pressure of 5 psi could increase power by 40 brake-horsepower (bhp) at the peak engine speed and over 60 bhp at lower engine speeds. The results show that turbocharged direct injection is a viable option for high performance two-stroke engines.