The new bi-fuel, 16-litre Tier 4 Interim engine from Volvo Penta is fueled by a precision blend of natural gas and diesel fuel to provide fuel cost savings and high power density. The TWG1663GE is 100 percent Volvo Penta, with no add-on aftermarket systems required. Natural gas is introduced upstream of the turbo-chargers, and an electronic air valve controls the amount of natural gas mixed. Engine compression ignites the diesel fuel, which in turn ignites the natural gas. Bi-fuel blending and combustion control is