The Delco Remy 18SI is a heavy-duty alternator designed for use in Sprinter 2500 and 3500 vans manufactured from 2002 to 2012 by Freightliner, Dodge and Mercedes-Benz.

The alternator has a dual internal fan design for improved cooling abilities. The dual fans mean greater air circulation over the alternator electronics allowing the alternator to run at lower temperatures and improving operating efficiency and durability.

The 18SI is designed to cope with the higher electrical loads on many Sprinter van applications while operating more efficiently and saving fuel.