Northern Indiana Manufacturing

Nim Alternator Pulleys

The pulley ratio is an important consideration in selecting an alternator pulley, since it is used to determine the proper outer diameter. The pulley ratio is the ratio between the outer diameters of the engine drive pulley and the alternator pulley.
A pulley with the desired ratio will drive the alternator fast enough at engine idle to charge the electrical system slightly, yet will not drive the alternator too fast (over speed) at the upper end of the engine speed range. In general, pulley ratios of about 2:1 to 3:1 provide good charging system performance and assure longer service life of the alternator bearings.

Northern Indiana Manufacturing (NIM) Manufacturers of V-belt pulleys. Types of V-belt pulleys for alternators.