Horsepower is horsepower?

BenK wrote:
Continues to be the marketing metric....HP sells

Out of context, as there is more to it

Or that HP is developed from torque. There can be torque with no HP, but
HP can NOT exist without torque. Why out of context just talking HP. Other
attributes to any discussion on HP are the other factors (attributes): RPM,
gearing in the tranny (both auto and manual), diff and the effective final
ratio to pavement (tire dia or rev's per mile factor)

The concept of torque without HP but HP can not exist without torque is lost
to most. Might help to see the formula HOW2 derive HP (generic)

HP = torque (ft/lbs) x RPM divided by 5252

It can get more complicated, as there are different kinds of 'HP'. Like 'draw
bar', 'brake', 'shaft', 'SAE gross', 'SAE net', and a big ETC...

Things like a high HP @ high RPMs might not be able to get the load going at
all, but a high torque ICE can easily...to then have that high torque ICE
lose a time to speed contest

But the bottom line is that HP sells and is all most folks ever care about. Plus
a time to speed race is the other thing they care about...

HP sells because that is a measurement that comprehends an engine's ability to do work. Torque without RPM does nothing. Just like talking about a max RPM spec for an engine without defining the torque at the speed, describing an engine only by its torque peak is totally meaningless. What if it makes 1000 ft-lbs but at only 500rpm? What about 100 ft-lbs but at 5000rpm?

That is why HP is the one term that combines torque and rpm to define the work output of an engine. Yes, in the real world that HP must be delivered through a drivetrain to be useful. That's why we have transmissions, rear axle gears, clutches and torque converters.

I can make hundreds of ft-lbs of torque with a 2x4. It doesn't mean I can pull a trailer up a grade.