Quote:
Originally Posted by Lonesome Trail
You're climbing a hill, it requires 'x' amount of energy to maintain speed.
Car A is a 4 banger with typical 4 banger torque band with a curve and peak around 4k RPM, Car B is an efficient V8 with flat torque curve and peak around say 2500RPM as is very common in today's engines.
For sake of argument both cars are geared the same, same size tires, etc.
Now both cars hit the hill at the same time, and to maintain speed Car A must really open the throttle to achieve enough power production to climb the hill, Car B cracks its throttle.
By your logic Car A is using less fuel because it's a small engine making more power per displacement, hence is more 'efficient' because of that ratio, correct?
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Let's revisit Car A and Car B going up the same hill. Let's hold all atmospheric conditions the same. Both Car A and Car B are maintaining the same speed up that hill, they hit the same pavement going up that hill, and the same driver takes each car alternately up that hill.
Let's also assume, for the sake of argument, that everything else about Car A and Car B are identical. They have identical bodies, identical trim levels, identical gearing, identical tire and wheel sizes, identical liquid capacities, have identical weight distribution, consume the same amount of electricity (identical alternator loading), an identical amount of drivetrain wear, and they both weigh the same.
If nothing else, Car B with the V8 will have a larger intake manifold vacuum than Car A with the 4-banger. Remember, Car A has a completely opened throttle, and Car B has it's throttle cracked open.
Generating an intake manifold vacuum requires work, and to generate a larger vacuum, a greater amount of work must be expended. Work requires gasoline in either Car A or Car B, so Car B requires more gasoline simply to push Car B up the same hill as Car A, everything else being identical.