The C15 is a heavy-duty diesel engine manufactured by Caterpillar. It is intended for fleet and line haul use. Caterpillar has won the J.D. Power and Associates award for “Highest in Customer Satisfaction with Vocational Heavy Duty Diesel Engines” six times. According to Caterpillar, no other engine manufacturer has received this award once.
The Caterpillar C15 is an in-line, six-cylinder diesel engine. The bore by stroke ratio is 5.4 inches by 6.75 inches, or 137 mm by 171 mm. The displacement is 15.2 liters, or 928 cubic inches. The power rating when used in a truck or bus is 435 to 625 horsepower at 2,100 rpm; RV and fire truck ratings are 600 to 625 horsepower at 2,100 rpm. The total torque output is 1,550 to 2,050 foot-pounds at 1,200 rpm. Total weight of the engine is 3,090 pounds.
The C15 features the Caterpillar Air Management, Precision Combustion, Advanced Electronics and Effective Aftertreatment — ACERT — technology, which improves fuel economy, reduces emissions and ensures power performance. ACERT consists of a clean-induction technology, a variable-valve actuation turbocharger, an electronic control module and a diesel-particulate filter. The engine also features the ADEM A4 electronics system, which has three times the memory and five times the processing speed of the ADEM 2000. The engine sports a single-piece steel-piston four-bolt connecting rod and a high-efficiency water pump to provide reliability and durability.
According to Caterpillar, “laboratory tests and engine disassembly analyses indicate the Cat C15 engines are expected to have a B50 life of one million miles with Cat’s recommended maintenance.” The C15 was built to be compliant with the 2007 Environmental Protection Agency’s diesel emissions regulations. A compressor brake is available on the C15, and it is designed to allow for a simple after-purchase modification to increase horsepower.
Weight and Gearing Considerations
When equal to or less than a gross combination weight — GCW — of 80,000 pounds, a truck with 1,750 foot-pounds should have an axle ratio of 1,400 rpm at 65 mph. When over 90,000 pounds GCW, a truck should be geared at 1,500 to 1,650 rpm at cruise speed.