This tool will allow you to create sound files for your engines (sfxBlend2D) in a few simple clicks. You can check it out on Github as all the patch notes and releases are on there https://github.com/ZilverBlade/Sound2sfxBlend/releases However you can still give suggestions here and I'll have a look at them every once in a while. I also made a short video about it Example of creating a blend file: Note: in case you try to replace vanilla BeamNG sounds, the tool prevents you from doing that as I wanted to make sure in case anyone uploads these doesn't unintentionally mess up someone's sounds (e.g. a vehicle mod uses sounds with a blend name which happens to be the same as a vanilla BeamNG sound). It works by looking at your sound files, and looks at any numbers in the sound file and uses that as rpm (e.g. ENGINE_3400RPM_ON will be used as 3400rpm). Although, if there are any other numbers, it will mess up the system (e.g. V8_5000_onthrottle will be used as 85000rpm, because it thinks the 8 in V8 is part of the rpm name). I am planning to add an option that lets you cut out a certain part of the sound file name to prevent that from happening. Of course to be able to use the sounds you've created you need to modify the soundConfig lines in your .jbeam files of your mod.
Update: a while ago i also released the ability to ignore characters when creating the blend files as for the issue i said earlier For whatever reason i can't edit the original post so that piece of text will stay there.