This sound mod is using the same sound files as my other sound for the LeGran, but has been modified for the hopper.
The maximum rpm sound is higher pitched and louder than it is on the LeGran as it would be in the real equivalent car, a v6 Jeep Wrangler.
Original sound mod: https://beamng.com/resources/bruckell-legran-v6-
Install to .../BeamNG.drive/mods
Disable any other sounds for the hopper in the in-game mod menu so the two mods won't interfere.
Experimental Hopper v6 Engine Sound 1.0
A slightly modified version of the LeGran sound