It truly works fine for me. I have about 10 engine mods for mine, i have 3 V6, 2 cummins, a V10, and stock engines.
I just today got the game and got some cars and found this engine. Tried getting the engine to show up but no luck. After that I saw Mat say about renaming the files, that's a no go. Car that has the engine on the folder, wont load up at all. Can you say some cars you have tested, so I can test them too? PS. After game install, i started up and it recommended me to update so maybe that's the reason? EDIT: I opened up your file in notepad and it has nothing common to other _engine_ files I have in any cars. Infected, compromised, transformed??
It might be helpful to actually mention what cars this engine will work in in the OP. Because it doesn't work in every car as your OP would lead everyone to believe Very misleading.
Been getting enough reports of it. Just gonna take it off so nobody has another issue. Apologize for the inconvenience this file may have caused.