A Simpler Explanation Of The Measurement Of ONE HORSE POWER

MEXICOWANDERER wrote:
Torque

You probably mean torque of the engine's crankshaft as applied about directly (~1:1 transfer ratio) to the jet pump.

However, perhaps the gas engine should have been run at a higher RPM to actually get full it's full HP, and then the appropriate gear-down-ratio (via gears, pulleys, belts, etc.) used to reduce the spin rate of the jet pump to what it would be when powered with an electric motor.

It's a bit of a dance to properly tap a high-RPM-band gas engine's horsepower so as to hit it's sweet spot crankshaft torque required to get the needed torque on the axle spinning the load. A diesel has a much more restrictive RPM range, so it seems like it pulls loads "better" because it sounds like it's working less and it's doing it with less gear changes.

Modern gas engines have a bunch of gears for several reasons.

Torque

Dusty R wrote:
I don't know why but I have found that it takes a 2hp gas engine to do the same work that a 1hp electric motor will do.

Dusty

I remember back when growing up many years ago on a farm, we had a power outage. My dad then connected up a 2hp gas engine to the 3/4hp electric jet pump. It would just barely run it at wide open throttle.
The rpm was near the same at 1 to 1 ratio, about 3450-3500 rpm.

larry cad wrote:
Torque is constant over the RPM range, while Horsepower is a straight line function of RPM. Thus, the diesel engine, which operates with a typical limit of 2400 RPM produces more torque than a typical gas engine which operates up to 5500 RPM. Another factor that produces torque is larger displacement (BIG pistons)

The formula for HP is torque * RPM /5252, so HP is a function of RPM and torque. Torque is not constant over the RPM range of any engine. This is why people talk about "torque curves" of engines. Although electric motors have near flat torque curves (which is why train locomotives are diesel/electric). Diesels deliver torque more consistently through the RPM range compared to gasoline engines. But, there's a curve - torque delivery is not a constant. Since diesel engines don't rev as high their horsepower is relatively low (RPM is a variable in the HP calculation) when compared to a gasoline engine because the gasoline engine can produce 2 or 3 times the RPM.

Dusty R wrote:
I don't know why but I have found that it takes a 2hp gas engine to do the same work that a 1hp electric motor will do.

Dusty

Since horsepower is horsepower - of course there have to be other factors at play.

Instantaneous-response shaft torque of an electric motor over that of a gas engine, for instance?

However once the torque change has been dealt with and the load is back to running as steady-state - and if the proper gearing is used for both spinning motors for conversion of their horsepower - then a 1 HP gas engine must be able to do the same as a 1 HP electric motor.

I don't know why but I have found that it takes a 2hp gas engine to do the same work that a 1hp electric motor will do.

Dusty

Housted wrote:
One horsepower equals 550 foot pounds (pound feet) per second.

In high school, in physics class, I generated 1 horsepower by running up a flight of stairs. :)

Housted

In order for you to have accomplished this feat and assuming you weighed 165 lbs you would have had to run up that flight of stairs in 3 seconds .... that's pretty fast.

An engine's peak horsepower is an indication of how much fuel that engine is capable of consuming per unit time.

An engine's peak torque is an indication of how much fuel an engine is capable of burning per revolution.

jharrell wrote:

pnichols wrote:


I've always thought that the diesel owners thought that their rigs pulled better because they didn't have to rev the engine very high to tap the engine's horsepower. Kindof a preference thing, not really based on engineering facts.

The V10 in our small motorhome will paste me back into the seatback if I punch it, but it takes 4000-5000 RPM to do it.

You can get any torque number you want at the wheels through gearing, horespower cannot go up (only goes down through losses from engine to wheels). Gears exchange RPM for torque. Your diesel engine puts out 1000 lb-ft of torque, who cares, I can get 10000 out of a lawnmower engine with the right gears.

You cannot measure power directly, dynos measure rpm and torque to derive horsepower. Torque is meaningless on its own, it requires the rpm component to get a meaningful measurement of power.

Many of those here should recognize this relationship as the same one between volts, amps and watts. Watts are power (746 per hp in fact), volts is equivalent to torque and amps equivalent to rpm. Using a transformer/coil you can exchange one for the other but watts stays the same. Just think your spark plug gets 20000v from a 12v system through a coil, you can get 20000 lb-ft of torque from a 12 lb-ft motor through gears.

Again you don't measure watts directly either, you measure voltage and current to derive power.

jharrell ... an outstanding post above ... and finally the voice of reason speaking clearly.

You substantiated what I've been saying for years - the only torque that counts is the torque on the drive axle(s) - and that can be created from horsepower through gearing regardless of whether it's diesel or gasoline or alcohol or propane or natural gas.

BobsYourUncle wrote:

wanderingaimlessly wrote:

Boon Docker wrote:
One Horse Power Hybrid



Wonder how many miles per bail?

Wonder which group will protest its emissions? :)

Likely the driver of that car. Note the direction the horses butt is pointed....
:B:B

With necessity being the mother of invention, this could give rise to the next generation of windshield wipers. I dont think the current styles are going to be up to the task.