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iScience
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What is it about acceleration that makes it less fuel efficient?
iScience said:What is it about acceleration that makes it less fuel efficient?
Bystander said:"Raw gas" through the carburetor in the "old days." Nowadays? Nothing but the sudden stops and starts. Everything burned in the engine goes up in smoke from the brakes.
How about firming up the question. Less efficient than what? And by what measure of "efficiency"?iScience said:What is it about acceleration that makes it less fuel efficient?
LOL, I had to look that one up!Khashishi said:spherical cow assumptions
berkeman said:LOL, I had to look that one up!
The way you define 'Efficiency' will affect the result.iScience said:What is it about acceleration that makes it less fuel efficient?
houlahound said:Really??
Accelerate/coast is efficient?
I would have thought continuous small acceleration?
That's one way of looking at it. But, in the old days, you could buy a 'vacuum meter' which told you the pressure in the induction manifold. To help you get the best mpg, you avoided letting that pressure increase so you had to keep the butterfly valve as closed as possible - i.e. throttled.billy_joule said:Would you expect an engine to be more efficient when it's throttled?
I assume you are being ironic here. The stench of unburned fuel at drag meetings tells you that drag cars are not designed for efficiency (conventional or mpg type).houlahound said:So a drag car is fuel efficient??
Throttles I assume are wide open.
houlahound said:So a drag car is fuel efficient??
Throttles I assume are wide open.
billy_joule said:...Would you expect an engine to be more efficient when it's throttled? (literally choking the fuel & air flow through the engine) or when the throttle is wide open and fuel & air flow is unrestricted? Modern injected engines are a bit smarter with how throttling is done but I suspect they're all still more efficient at WOT (wide open throttle).
Max Power capability doesn't come into the definition of efficiency. A grossly underrun engine could still be run at high efficiency. The fact is that F1 cars need to do a job which involves loads of acceleration and braking. This uses up a lot of fuel. If they were not built with an eye to efficiency (to do that job), they would need to make more pit stops and, hence, lose races. I would say that means their engines need to be as efficient as possible so that the majority of the energy wasted in the brakes and by the tyres on corners can be replaced using as little fuel as possible. But, of course, we are being very cavalier in our definitions in this thread and the process of getting from A to B on the race track uses up a lot of fuel. The car starts at rest and ends at, say 150k/hr and that added Kinetic Energy is the only output energy that they have obtained from the whole exercise. (Plus I find motor racing noisy and boring - so I may be biased here)houlahound said:F1 cars I would think are not efficient, they are grossly overpowered
Very simple question you ask, but I didn't find a good answer. First let's clarify your question, because it is poorly stated.iScience said:What is it about acceleration that makes it less fuel efficient?
houlahound said:F1 cars I would think are not efficient, they are grossly overpowered to compensate for their constant deceleration/acceleration around tight tracks and cornering.
houlahound said:Their top speed is not great and doesn't have to be.
houlahound said:Their was a hybrid fuel / human power race with a total fuel limit. Efficiency became important for competitors.
Accelerating cars use more fuel because the process of acceleration requires the engine to work harder, which in turn burns more fuel. The more fuel the engine uses, the less efficient it becomes.
As a car's speed increases, its fuel efficiency decreases. This is because the faster a car travels, the more wind resistance it experiences, which requires the engine to use more fuel to maintain the speed.
Yes, driving techniques can significantly impact a car's fuel efficiency. For example, aggressive driving, such as quick acceleration and braking, can use up more fuel compared to smooth and gradual acceleration and braking. Additionally, maintaining a steady speed and avoiding unnecessary idling can also improve fuel efficiency.
The weight of a car can play a role in its fuel efficiency. A heavier car requires more power to accelerate, which means more fuel is needed. This is why smaller and lighter cars tend to have better fuel efficiency compared to larger and heavier vehicles.
No, idling a car is not more fuel efficient than accelerating. In fact, idling a car for more than 10 seconds uses more fuel than turning off the engine and restarting it. It is more fuel efficient to turn off the engine when stopped for a prolonged period of time.