If an engine with high horsepower can gear down to increase torque, couldn’t a high-torque engine be geared up to increase horsepower?

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Just wondering why, in these discussions, people always say the former and not the latter.

In: Engineering

12 Answers

Anonymous 0 Comments

The way I see it as a non car guy: horsepower is simply the measurement of how much total power a vehicle has at max potential.

But torque is what makes a vehicle accelerate faster or slower.

You can gear down with high horsepower because even if you have 1000 ponies you won’t accelerate to that highest speed if you start out in the highest gear that takes the longest to spin, but if you start in the lower gear (IE more torque) you spin that gear super fast to get to a maximum middle speed for that gear, and then shift it into a higher gear that goes from the max speed of 1, to the max speed of 2.

essentially you can’t make something that has more torque suddenly gear up and increase the ponies because the gearing up isn’t increasing power it’s just increasing the acceleration with the available power.

Anonymous 0 Comments

As others have said, you can’t increase hp with a transmission. However, of one engine can do 100Nm at 6000 rpm, and another 200Nm at 3000 rpm, the latter can have twice the gearing ratio and both cars would accelerate at the same rate at that point in the rev range. This is purely due to both engines delivering the same amount of hp at those revs.