The effect on fuel consumption and emissions of switching from two-valve to single-valve EIVC operation in
order to generate swirl intake structures in a four-valve, pent-roof gasoline direct injection (GDI) engine has
been investigated. Mie imaging of the fuel spray propagation, along with PIV measurements of the intake flow
field have been taken in an optical engine, and fuel economy and emissions measurements have been made on a
thermodynamic engine with identical geometry and ancillary systems.
The measurements show that fuel economy can be improved substantially when EIVC valve operation is employed,
and results differ when only a single inlet valve is activated. Bulk swirl structures are generated in the
engine cylinder which affect the atomisation and transportation of the fuel spray and engine performance. For
fuel injection after the inlet valve closing point, the reduction in shear forces and mixing from the intake air
structures is sufficient to cause engine misfires.