Originally Posted by Nithmo

What are you talking about? Fuel has nothing to do with it. There are plenty of times there is no fuel being injected- like when downshifting in high rpm and not hitting the throttle. The engine doesn't need to inject fuel because it is moving so fast, it just keeps moving on its own. It's more your rods breaking or your valves staying open and burning out due to the engine spinning faster than it is intended to.

The rev limiter won't save your engine on a downshift either. The synchro rev will push RPM up until redline, but only if the clutch is still pushed in all the way. As soon as you release the clutch, there is nothing the car can do to stop the engine from over revving and destroying itself.