There is a "random" factor within GPL that will give you an engine failure for no other reason than sheer bad luck. Rare, but it does happen. Naturally ALL of my engine failures are a result of bad luck, not bad driving
The most common reason for damaging engines in GPL is not when you are accelerating ( unless you consistantly speedshift without lifting between gears), but downshifting too early. I would suggest that you take a look at your replay, from the cockpit view, and watch that red pointy thing as you brake and downshift for corners. If you see that needle banging on the limiter then that is the cause of your engine failure. In simple terms, GPL simply registers the number of times that you exceed the max rev limit and it does not matter when or where that happens
You might need to try braking at the same point in future, but delay the downshifts by 0.5 secs so that the overrun from the engine does not force the revs too high. If you watch Beefpie's race, his downshifts at the end of the long sweep are all done at the last possible second. I am not sure if he uses paddles or a gear shift but he drops through those gears very swiftly with no load on the engine.
I