Description
The Paccar PX-9 and Cummins ISL9 (now known as the L9) are essentially the same 8.9-liter, inline-6 diesel engine. The PX-9 is manufactured by Cummins for Paccar, meaning the internal mechanics and core parts are identical, with only brand-specific aesthetic and exterior layout differences.
Key Identical Mechanics (Core DNA)
- Displacement: 8.9 liters
- Applications: Both are heavily used in medium-duty trucks, fire apparatuses, and vocational vehicles.
- Internals: The cylinder heads, camshafts, pistons, and base mechanical blocks are identical.
Key Differences
- Branding & Paint: The Cummins ISL9 is typically painted Cummins Red, while the Paccar PX-9 is painted a dark gray/black and features the Paccar name on the valve cover.
- Availability: Paccar-branded PX-9s are primarily found in Peterbilt and Kenworth trucks. Cummins ISL9/L9 engines are found in a variety of other makes (like Freightliner and International).
- Exterior Plumbing & Layout: Depending on the truck chassis, the layout of accessories like dipsticks, exhaust elbows, and turbocharger mounting angles can vary slightly to fit specific engine bays