The S series of 6 phase alternators offers incredible output in a compact and durable package. Highly efficient, these units use less horsepower than conventional 3 phase alternators. 12 diodes, twin rectifier plates and outstanding airflow ensure long service life, even in severe conditions. The 240 amp model offers the best balance between peak output, and output at engine idle RPM. NOTE: This unit comes equipped with a smaller 1.75 inch diameter alternator pulley, and will require a slightly shorter drive belt for proper belt tension.