why do some smaller engines have lower gas mileage than some larger engines?
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Very rarely is this true. Smaller engines tend to be more efficient. Significantly so.
You may see variations due to efficiency of different engines.
Examples would be helpful.
Very rarely is this true. Smaller engines tend to be more efficient. Significantly so.
You may see variations due to efficiency of different engines.
Examples would be helpful.
I recall a Top Gear where a BMW 3ltr was against a Toyota Prius Paris to London.
the Beemer was just ticking over but the Prius was being thrashed at the same speed.
unsurprisingly for motorway driving the Beemer is a better car
I recall a Top Gear where a BMW 3ltr was against a Toyota Prius Paris to London.
the Beemer was just ticking over but the Prius was being thrashed at the same speed.
unsurprisingly for motorway driving the Beemer is a better car
Inside an engine, there’s a mixture of fuel and air burning. The heat of this fire is what makes the engine run. The hotter the fire burns, the more power the engine will have. Now, with large engines, it’s pretty easy to keep the heat contained. This is just the same when cooking: a large pot will cool down much more slowly than a small one. In a small engine, you’re burning a lot of fuel just to have the temperature right. It’s more a heater than an engine.
This is very obvious in model aircraft engines. You can hold those in your hand. When you do the math, you’ll notice that they’re very inefficient. They’re burning lots of fuel for a little flying.
Inside an engine, there’s a mixture of fuel and air burning. The heat of this fire is what makes the engine run. The hotter the fire burns, the more power the engine will have. Now, with large engines, it’s pretty easy to keep the heat contained. This is just the same when cooking: a large pot will cool down much more slowly than a small one. In a small engine, you’re burning a lot of fuel just to have the temperature right. It’s more a heater than an engine.
This is very obvious in model aircraft engines. You can hold those in your hand. When you do the math, you’ll notice that they’re very inefficient. They’re burning lots of fuel for a little flying.
Power and demand plays a factor.
The more power an engine has, the more it can generate at peak efficiently.
See this a lot with semis, 2 identical trucks set at different horsepower ratings, the higher power always gets better fuel mileage.
Modern turbo engines are a great example of this. If you drive them like the factory tester going for the EPA certification numbers then they get good mileage. But take that same car out into the real world where everyone drives like an idiot, get on the boost and it drinks fuel like mad.
Because to get the power out, you still need to put the fuel in. Sometimes over-boosting small engines makes it worse than that bigger lazy engine that never breaks a sweat.
That said, peak engine efficiency at a steady cruise is somewhere around 70% load. So theoretically the small engine is better.
Power and demand plays a factor.
The more power an engine has, the more it can generate at peak efficiently.
See this a lot with semis, 2 identical trucks set at different horsepower ratings, the higher power always gets better fuel mileage.
Basically, large engines always have an advantage when it comes to peak efficiency, but an engine has to be built to match a load. Engines perform best at lower RPM but almost max. throttle. If you have a big engine giving 200 HP at low RPM and full throttle and a smaller engine giving 200 HP at redline RPM and full throttle, the small engine will be less efficient, and because it still puts out the same power, will consume more fuel.
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