Caterpillar C15 Engines — 15.2L Heavy-Duty Diesel

The C15 spans distinct designs. The early single-turbo engines, identified by serial prefixes like 6NZ and MBN, are favorites for their durability and the ease of tuning for power and economy. The later ACERT C15 introduced twin turbochargers and revised fuel and emissions strategy to meet tightening standards. Each generation has different parts and characteristics, so identifying yours by serial-number prefix is the key to a correct match.

The C15 is a big-bore over-the-road engine with ratings commonly running from roughly 435 to 625 HP and high torque output, making it suitable for heavy line haul, oversize and heavy-spec vocational work. It powered Class 8 tractors from Kenworth, Peterbilt, Freightliner, International and Western Star. Because so many trucks were built with the C15 and CAT no longer produces on-highway engines, demand for quality used and remanufactured units remains strong.

A dyno-tested used C15 is the quickest and most affordable route back to the road. A remanufactured C15 is restored to specification with new bearings, liners, seals and reconditioned heads and crankshaft, carrying the longest warranty and service life. We supply both long blocks and complete engines and explain core-exchange requirements up front. Given the C15's value among buyers, we are careful to verify and document the condition of every unit we quote.