Quote:
Originally Posted by Tcoat
Even a brief over rev can be disastrous. But that is if you drop a couple of gears and shoot it up a 1,000 or more RPM. This is when you bend and break things that are just not designed for that sudden or intense of an impact. It is the abruptness of the increase that causes issues not the duration.
In this case dropping one gear and going up a couple of hundred (which as pointed out is about all you could do at that speed) is not going to harm anything. The cut off isn't a drop dead line where one RPM over is going to blow an engine. There is a safety margin built in to deal with exactly this sort of situation.
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Here are some points that cover my thoughts:
https://www.google.com/amp/s/amp.red..._of_an_engine/
Essentially the limits to revving seem to be with handling the heat/friction from the increased speed, handling the forces on parts like the pistons from the increased speed and finally handling the air flow required to not bottleneck the process.
My thoughts are that the forces are too temporary and the heat isn't able to build enough to matter.
The example that comes to mind that is relatable is how the foot experiences two to three times a person's bodyweight when it strikes the ground during running. So a 150lb person experiences 300-450lbs on one foot. Most people would buckle their ankle under that constant load if it wasn't for a half second like it is with a foot strike. Moral of the story is that peak forces may not matter as much as sustained forces. And there just isn't enough time in my opinion for enough heat to build to effect spring recoil or to cause bearing surface breakdown/thinning.
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