Creating a smooth car engine sound...

Okay so I'm making a racing simulator, and I really really want an engine sound. I decided that I would make the volume of the sound increase as you increase your RPMs. But I didn't even get that far...

Code:

---

onClipEvent (load) {
this.attachSound(eng)
}
onClipEvent (enterFrame) {
vol = _root.car.rpm/80;
this.setVolume( vol )
this.start( 0, 1)
}

---

Thats the code I have in the tachometer. eng is the engine sound I was using. The car's maximum rpm is 8000, so I divided by 80 so that vol would be from 0-100.

After that I have no idea what I'm doing... The sound plays once, but I want it to play every time the clip enters a frame, and also change volume as your RPMs increase or decrease...

Is this at all possible with flash?

thanks