why do some smaller engines have lower gas mileage than some larger engines?
In: 208
Poor design or application. You could “technically” move a dump truck with a dirt bike engine and some insane stack of gearing but it would be hugely inefficient because to get the most out of it you would be running the engine at WOT all day.
It almost always makes more sense to have a more powerful engine that doesn’t need to constantly run at 100% output, not only for obvious wear&tear reasons but also because combustion engines are most efficient when operated in a specific range of speeds, and because it’s a hell of a lot easier to build and operate a vehicle where you can modulate the speed with the engine instead of having 50 gears or some overly complex and unreliable CVT. .
Ideally the engine will be designed (or at least selected) for the vehicles use (will it be towing or hauling heavy loads? Is it a tiny lightweight commuter vehicle meant to be as fuel efficient as possible? Is it an off-highway vehicle that doesn’t need to reach high speeds?). Other considerations like duty-cycle (will this engine be running 12-24 hours a day? It’s probably overbuilt and underpowered if so) and maintenance/service intervals come into play as well, although more commonly in industrial applications. For passenger vehicles, fuel efficiency and cost of production are by far the largest factors.
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