The engine was coupled to a direct current (DC)
Indicated fuel consumption was calculated from the measurement
of the intake air flow rate which was made using the volumetric
air flow meter (VAF). The load of 8.5 bar IMEP was chosen
to study because it represents one of the worst conditions for
engine knock in this naturally aspirated (NA) engine, as well as
being an engine load that is highly relevant for both NA and turbocharged
DISI engines, increasing the usefulness of the data
produced.