Valeo SA says that extensive R&D into combining functions of a standard engine-mounted alternator with that of a starter motor has produced the Starter Alternator Reversible System, which has “achieved its technical objectives.”

The unit looks like a conventional engine-mounted alternator, but aside from generating electricity, it also can perform as a starter motor and crank the engine at much higher rpm and with 15 decibels less noise. Valeo says the unit also enables “Stop-and-Go” operation that switches off the engine during idle, such as at stoplights. Because of the swift and silent engine-starting ability, the engine then is re-started virtually instantly when the driver either engages a gear or releases the brake pedal of an automatic-transmission vehicle.

Valeo says the Stop-and-Go function generates a 10% fuel savings and a similar reduction in carbon dioxide emissions. Most important, the unit can be specified for current engines by using existing alternator mounts. The high-efficiency SARS also generates higher electrical output — 1.5 kW to 2.5 kW at 14 volts — that the company says will enable OEs to specify more electrical features.