Middcore t1_jaay03j wrote
I want to add just as a point of (possible) interest that although you may have only heard this terminology in reference to car engines, there are also major implications (or at least used to be) in aviation.
As a plane gains altitude, the air becomes thinner. In a plane driven by a piston engine or engines turning propellers, this means you have to adjust the mixture of fuel and air in the cylinders to compensate, but it also means that even if you adjust the mixture optimally engine power inevitably drops off the higher you go. However, this can be to some extent alleviated by using forced induction.
For jet aircraft (including turboprops, which use a turbine engine to turn a propeller rather than a piston engine) this isn't a concern, and the piston-engined aircraft that still exist usually no longer operate at a high enough altitude to make forced induction necessary.
Gaboik OP t1_jabc3fi wrote
Woah awesome! Thanks for pointing it out !
I had heard about pilots needing to adjust the mixture and all but it hasn't occured to me the less oxygen = less combustion hence less energy !
bal00 t1_jabyerq wrote
It's also true for cars driven at high altitudes. A naturally aspirated engine makes less power in the mountains than it does at sea level. Turbocharged cars can make up for that for the most part by just pushing more of that less dense air into the engine, so the power loss is much less severe.
DisorderOfLeitbur t1_jaep9zu wrote
Shipbuilders also had their own interesting wrinkle on getting enough air into the engine.
Late nineteenth century engines needed a big opening that the stokers could shovel in the coal. You couldn't pump extra air into the fire, because it would flow out too easily. The solution was to keep the entire engine room at high pressure with fans blowing air in from outside.
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