Fuel Economy Question

>>16843348
weight, aerodynamic, style of driving

>>16843376
>style of driving

as i said, assume both cars are driven in the same manner

>>16843348
Usually yes. The only time it isnt true is if the car is very heavy and the smaller engine has too little power. Then you have to mash the pedal to go anywhere and it ruins the fuel economy

>>16843448
So basically a lot of newer econoboxes that are heavy and have tiny engines?

an example: would a 2.0 NC miata have better mpgs than a 1.2 fiesta or golf?

>>16843486
sadly no one knows. if only there was a way to measure and publish such data, it could change everything.

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>>16843500
luckily there IS a cure for your bullshit

>>16843348
Given the conditions in your post, yes, the 3 cyl would use less fuel.

The issue is in real world driving, a smaller engine lacks low end power, so people floor it everywhere. That's why the new turbo 4s do so well in testing, and so poorly in the real world.

The amount of power necessary to accelerate x amount of weight is going to be constant regardless of what kind of engine you have.

All engines make power the same way, more or less. The difference in fuel economy will be in losses to friction. A 8 cylinder engine is going to have more internal friction that a 4 cylinder. The 8 cylinder is also going to weight more, years op did say weight being the same but it won't be. The 8 cylinder will also have more peak power so many drive line components will need to be stronger and heavier.

>>16843543
even with it being necessary to floor it everywhere, would the smaller engine still be better?

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>>16843348
If all conditions are the same and the engines are build roughly in the same way, the smaller engine will need less fuel.
The gear ratio used is also a significant factor, since your engine is more efficient at high load and low rpm than on low load and high rpm.(pic related)

The only exception would be at speeds over like 100mph when the small engine would need to deliver more power than it does in its sweetspot of efficiency.
>>16843486
A NC miata should get a better fuel economy than a 1.2 fiesta or Golf above 100mph, but a worse on normal highway speeds.
>>16843543
Flooring isn´t the factor that ruins your fuel economy, reving the schit out of your engine ruins your fuel economy.
oic related shows the specific fuel consumption of a engine at different rpm and cylinder pressure

Weight, aero dynamics, and final drive gearing (as well as transmission gearing) play heavily into fuel economy.

>>16843567
Yes, as long as you don´t have to rev it above maximum torque most of the time.
My naturaly aspirated 1,0L 3-cylinder gets about 60mpg when I drive normal, when I drive fast (100mph) that shrinks to about 35 mpg.
That is still pretty good for that speed, but not much better than a bigger engine woul have been.
But since driving that fast is not a thing most people do daily, a small engine improves fuel economy.

>>16843348
2d-3d rule
An engine with twice as much mass does not have twice the volume.
If you scale volume linearly, mass is exponential.

>>16845258
The mass of a object is proportional to its volume, so displacement and weight scale linear if the engine configuration stays the same.

>>16843348
Depends. Combustion engines run at a certain air/fuel golden ration which is between 12.5 and 13.5. A larger displacement moves more air thus more fuel is needed. However given vehicles of the same weight and drag coefficient there will be a point on a graph where a weaker engine and a stronger engines speed/fuel consumption will overlap or even cross