International 9900i Cummins Isx15 Engine Sound ... -

For linehaul applications, the engine’s "acoustic sweet spot" and maximum efficiency occur between 1,400 to 1,500 RPM at highway speeds.

The equipped with the Cummins ISX15 engine is renowned for its classic "heavy-duty" acoustic profile, characterized by a deep, resonant diesel snarl and a powerful exhaust note. Acoustic Characteristics International 9900i Cummins ISX15 Engine Sound ...

Typically operates at an optimal idle speed of 700–750 RPM . At this stage, the sound is a steady, rhythmic thrumming. For linehaul applications