Hesselman engine

The Hesselman engine is a hybrid between a <a href="/facts/Petrol_engine/oj3XzkQU">petrol engine</a> and a <a href="/facts/Diesel_engine/9B9opxvA">diesel engine</a>. It was designed and introduced in 1925 by <a href="/facts/Sweden/u3qC7lyj">Swedish</a> engineer <a href="/facts/Jonas_Hesselman/y9LjzbrV">Jonas Hesselman</a>. 
In a Hesselman engine, fuel is not injected during the suction stoke along with the air, as would be the case in a conventional <a href="/facts/Otto_cycle/jP5s560r">Otto cycle</a> engine, but is instead injected during the compression stroke slightly ahead of the spark. Hesselman engines typically have lower efficiencies than diesel engines but can run on the same fuels without needing to sustain high compression ratios, and therefore could be made smaller, lighter and cheaper. 
Most Hesselman engines were built during the 1930s and 1940s by firms in Sweden and the United States for use in both heavy vehicles and stationary industrial applications.

Hesselman engine open-in-new

Hesselman engine