4021423
Short Isolation And Qsl Series Engine
Cummins®

Short Isolation Rubber (SIR) is a component of a truck's suspension system that helps to absorb vibration and reduce noise. It is made of rubber and typically measures only a few inches in length. SIR is designed to isolate the vibrations caused by the engine and other components from the rest of the vehicle, improving overall ride comfort for drivers and passengers. The QSL Series Engine is an advanced diesel engine used in heavy-duty trucks. Developed by Cummins, it features Quantum System Lamination technology, which improves fuel efficiency, reduces emissions, and increases durability. The QSL series engine has a displacement of 8.9 liters and produces up to 450 horsepower and 1,250 lb-ft of torque. It also meets EPA Tier 4 Final emissions standards without the need for aftertreatment equipment or diesel exhaust fluid (DEF). Part number 4021423 refers to a specific version or configuration of this engine for use in particular applications or vehicles.