The fundamental to improving fuel efficiency lies inwards raising an engine’s thermal efficiency. This tin move done past times increasing the expansion ratio. The expansion ratio is the sum of run the engine does each fourth dimension the air-fuel mixture inwards the cylinders detonates. However, inwards conventional engines the expansion ratio is the same every bit the compression ratio, as well as thence increasing the expansion ratio volition too enhance the compression ratio. This is a work because a high compression ratio causes abnormal combustion, or knocking.
The respond is the Miller-cycle engine. By delaying the closure of the intake valves, compression genuinely begins business office means through the compression stroke, which results inwards a reduced compression ratio. At the same time, changing the cast of the piston crown decreases the combustion sleeping accommodation minimum volume, resulting inwards a larger expansion ratio. In this means nosotros tin decrease the compression ratio as well as spell increasing the expansion ratio. In other words, the Miller-cycle engine has a higher expansion ratio than compression ratio.
Mazda’s naturally-aspirated MZR 1.3L Miller-cycle engine delays the closure of the intake valves to better the thermal efficiency (high expansion ratio). Sequential-valve timing (S-VT) is too employed to optimize intake valve timing as well as ensure sufficient torque for cruising as well as accelerating. Furthermore, the engine is mated to a continuously variable transmission (CVT) for a perfect blend of responsive acceleration, shine gear shifts as well as top-class fuel economy.
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