Diesel vehicles are another platform for our dual fuel conversion. In the dual fuel conversion, diesel engines are designed to consume natural gas with a small, pilot injection of diesel fuel to ignite this fuel mixture. Natural gas is effective in this application because it has an extremely high resistance to self ignition from the high compression-ratios used in diesel engines. The critical compression ratio (CCR) of natural gas is about 15:1, depending upon the amount of methane in the fuel. Like a conventional single-fuel diesel engine, there is no throttle valve and load control is done by adjusting the fuel mixture. These engines are some of the most efficient in terms of kW produced per Joules consumed (hp produced per BTU consumed) because of the thermal efficiency of the diesel cycle.