I really really doubt others have done that, and if anyone actually has I'd love to read how they did it. What I think you'll actually find it that people have made a simple single motor rpm loop, like a horn file: Startup -> Single rpm -> Shutdown. To me and I guess most others not what we'd call a prime mover/engine sound as it doesn't have a range of rpm sounds.
So, if your wanting a prime mover/engine sound with a range of rpms (think notches) then my first reply still stands. If you can provide otherwise that we can make these please do so here and I'll stand humbly corrected.
If you just want a single rpm engine sound then yes, that can be done by us users. No one has posted or made reference to such a sound to this forum before.
- Tim