Fuck Cars
A place to discuss problems of car centric infrastructure or how it hurts us all. Let's explore the bad world of Cars!
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I wonder if there’s even a gain in total miles they can travel given how much air resistance that sail adds. Wonder what RPM the engine is pushing going highway speeds.
Same speed = same RPM, regardless of load / air resistance. Unless they have to drive in a lower gear to make it work, but I doubt that
You’re right RPM is tied directly to wheel speed. There is increased fuel consumption because the load on the engine is higher.
Wouldn't that mean that a car with a trailer uses the same amount if fuel? Which it doesn't, I am sure.
It just has to burn more fuel for each combustion cycle to keep the engine spinning at the same speed. It's like how it's easier to pedal a bike down an incline versus up the same incline, but your legs will still pedal at the same rate for the same speed (assuming you don't change gears).
As my reply in another comment
No, because an engine can use different amounts of fuel even at the same RPM. At the most extreme, a car can go downhill at high RPM with no fuel injection at all, only driven by gravity.
During normal driving, the engine's crankshaft has a hard link to the wheels. It's going through a couple of gears etc. inside the transmission etc., but the speed conversion from that is fixed within a single gear. This means that the speed the vehicle is going is directly tied to the RPM the engine is turning at. For every gear, every possible vehicle speed correlates directly to a single specific RPM of the engine. Fuel use at that RPM can vary a lot though, entirely depending on the amount of energy needed to keep the engine at that speed with air resistance and other factors trying to slow the car down through the drivetrain.
I am following your reasoning here. The thing that tripped me up was the last sentence of your previous comment. I understood it like it's not necessary to switch gears since the load has no real effect on the force needed to move the car. You probably meant that the engine could handle the extra load while staying in the same gear and still use more fuel.
I think we are on the same page now
Ah, yeah, that's what I meant. I just assumed that at highway speeds, the additional drag in this scenario probably wouldn't be enough to warrant shifting down. Although to be fair depending on the engine it totally might, that was just a quick generalization on my part
More surface area = more drag. A big ol non aerodynamic cube will definitely be adding more drag. Other than that, yeah load doesn't really effect mpg
Yeah for sure. I'm just saying that the engine RPM won't be affected as the original comment implied. Drag and mpg will definitely be higher.
Unless it's a CVT, which it probably isn't