Making Engine Sounds

[Falken442]

How can I make a engine sound? I'm a massive fan of the NR and 48 class diesels and I want them to have the proper enginesound. The Models themselves that I have are fine, its the just the sound that bothers me.

I use Davidos NR Class locomotives and the 48s already in the game plus a few different reskins I found on the DLS.

-Eno