Quote:
Originally Posted by Daox
Could you explain how stuffing the engine with more air is going to help increase fuel economy?
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Because its a diesel.
Diesel and brayton cycle engines make both more power and are more efficient when they are fed as much air as you can get them. You never want to restrict the air flow into one of these engines. It just doesn't do anything beside burn more fuel and make less power.
The isentropic process starts the cycle, this means the more energy you start with in the cycle the more energy you will have through out the entire cycle and less energy will have to come from fuel.
Its not the air its self but the heat and pressure you get from compressing it is part of your energy for driving the engine.
The cool thing about diesels is their power stroke is an isentropic process also, that is where your compression energy is returned along with whats added by your fuel burn.
So there is no reason to start this process off with any less than the maximum amount of air you can get throught the air filter and down intake manifold.
This is well proven by N/A diesels running at high elevation, if you want the same level of power from them with say 10% or 20% less air you have to burn a lot of fuel to make up for it.
Brayton cycle engines at high altuide use ram air to make up for lack of air density. They depend even more on their air supply as they need it for cooling.
You can not get more fuel economy on a gas engine by trying to stuff more air into it because of isobaric expansion (throtteling losses) at the start of the cycle. Many have tried, all have failed. Simple thermodynamics forbids it the way we run our gas engines at 10% to 15% load nearly all of the time.
You can make them more efficient for the 5% of the time you really do need power when going up a hill, passing or getting up to speed on an on ramp.
So if you have a gas engine, this isn't going to do anything for you unless you are looking to "go fast" and generally get a lot less fuel milage.
For diesel owners its a ticket to more power and more fuel efficiency.