Originally Posted By: BigNick
I'm sorry, this doesn't make sense to me. If I all of a sudden start driving into a continuous head wind, it's logical to think that my engine would have to "work harder" to maintain the same speed before I hit this continuous head wind. How else would this be achieved other than by increasing RPM's?
Your engine "works harder" by consuming more air and fuel. RPM does not have to increase, and in the example cited, would not if the speed remains the same.
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Eg #2 Different scenario: All variables remain equal while in cruise control, when all of a sudden you begin on a continuous stretch of highway with a 15 degree incline. Your engine will have to "work harder" to maintain that set speed, and you will see your RPM's increase (as this is the only way an engine can "work harder" righ??? div>
How hard an engine works is related to load. This is not directly related to RPM. While an engine can make more power, and subsequently perform more work at a higher RPM, load can be applied at any RPM, and subsequently more fuel and air are required to handle that load and maintain that RPM.
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I'm no engineer. I'm open to opinions/statements. Just trying to understand something, that may have more than one explanation. I noticed something, i.e. the decrease in RPM's, after changing what I believe is only ONE variable (switch from dino to synth), and I agree that it may not be exactly correct and more likely more complicated than that.
Nice to have some detailed explanations besides people just replying by laughing, and not explaining anything. I have to admit, I'm still not convinced or agree to everything said, but appreciate the good responses to the discussion!
BuickGN's example of a bicycle should hopefully make it clear for you.
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PS: Think of this also: Not saying it is totally correct, but just think about it... Assume that ONE variable changed, leads to a decrease in RPM's to maintain the same speed ... Doesn't this explain the increase in MPG??? ---> The pistons spin 50-75 RPM's less per minute, hence you have less explosions in the chambers per minute, hence you burn less gas per minute, hence your MPG increase! ... haha makes sense to me! haha
Again, wide open to suggestions/opinions/engineering 101.
The pistons don't spin
They move up and down in the bores; the crankshaft spins via the force applied through the rods, which connect to the pistons, which are pushed down their bores through the process of combustion.
An engine can consume LESS fuel at a higher RPM; high load at low RPM will cause the engine to ingest more air and fuel to maintain that RPM than an engine spinning at a higher RPM under low load, where the opposite is the case.