https://documentation.beamng.com/tutorials/mods/installing-mods/ (Btw everyone press T when using the mod because something happenes )
Also DH Hyper Bolide and Bitron B2, possibly many, many more mods as well. Maybe the fact that it works for the devs and not for us might be related to the sounds folder being password protected somehow?
I found a temporary fix. There's a repository mod of a 358ci Nascar engine. Has more power than the original engine, and working sounds. Works really well too currently. Link: https://www.beamng.com/resources/358-ci-nascar-engine.16156/