Squid got one of them: corrosion prevention. Galaxee got three more: cooling, cleaning, and compensating for mechanical slack (valve lifters). Lubrication accomplishes two things: friction reduction and wear reduction. That's six; here are four more: Cushions shock (Galaxee said vibration reduction, which is close but not accurate). Heats (the intake manifold to pre-heat the fuel air mixture for better efficiency. This is more common in high powered aircraft engines). Seals (the piston rings, contributing to increased compression). Hydraulic actuator (In aircraft with constant speed propellors, the engine oil is used as the hydraulic fluid in the propellor dome). Galaxee suggested two things that to my mind don't qualify - in 2 stroke engines the oil is mixed with the fuel - but that's not a function, that's just how the oil gets put into that type of engine. The functions it performs are the same. The 2nd suggestion was noise reduction. That's a tough one to disqualify because it's true. But noise is a byproduct - not a function (Harley drivers notwithstanding). Well, if you've read this far here's another Quiz: In a 4 stroke reciprocating engine, at what points of the cycle and for how long at each point is the connecting rod undergoing tensile stress (being stretched)?
Well, during the intake stroke. The other three (compression, power, and exaust), the rod would be experiencing a compressing force.
he'd debate that they're essentially the same. typically doesn't apply in his field (automotive) he says "hey this is priuschat, not planechat!" :lol: nothing against planes, he'd love to get his pilot's license someday. busted him there. he said that and i made him explain it to me, and i reworded it. my bad. automotive equivalent: vvt-i system. just thinkin' aloud on that one. he will reluctantly lump that in with vibration reduction/shock cushioning. clarify "reciprocating engine." he's really only heard the term used for very very small engines.
You're killing me here! First oil... and now reciprocation? When will the messy, inefficient madness end!? The whole reciprocation thing is an exquisite example of inelegance... you accelerate a mass for just long enough to stop it, turn it around and accelerate it in the other direction. Eeek. Sorry. I'm not playing nice. I'll stop.
noise maybe a by product of the engine, but noise reduction is a desired component of any kind of engine maintenance and therefore i do not accept your reasoning.
