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Originally Posted by blue2000s
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Well. what you posted is a post from a guy who says he read a report by SAE on engine wear, which was measured by metal part. in the oil. Lets start there.
I agree that wear is greater while the engine is getting to operating temps. I would also agree that wear would be greater under load. ie. hammering the throttle and putting the engine under load. Of course, that is one way and likely the most frequent way that most of us GET TO THOSE HIGH RPMS!
Are you suggesting that we drive our Boxes very gingerly on our way to 6000 RPMS and they leave them there on cruise control? If that is the case, wear would be lower than the classic jack rabbit start. However, at 6000 stress and wear would still be higher than 3000 RPM, all things being equal.
Moreover, the measurement of particulates in the oil is not a very rigorous way to measure "wear" in a classic sense. In fact, one way you can generate more metal in the oil is to change it too frequently (source: Bob is the oil guy).
Lastly, if you search this thread, you will find reference to a study on piston ring wear and RPMs. There is a correlation, hard to imagine how there could not be.
Really, the last point. In a reciprocating piston engine, what happens to the forces of stopping and starting a piston throug the cycle as the RPMs increase?
Do the forces increase or not as RPMs increase or decrease or stay the same?
Is "wear" and stress, metal fatigue, bearing wear, reduced at 6000 RPMs or increased vs say at 3000 RPM?
Unless something happened in the universe last night to change physics, I would say that forces are increased at higher RPMs.
Do increased stresses and increased friction rates on metal parts, bearings etc. improve their useful life or decrease it?
PS-Those racing engines are designed to last, ie enhanced casting techniques, allowy metals, six main bearings etc.
They simply grenade anyway. Don't you think the guys would LIKE to get two races out of an engine?
Just a thought.
