Bhp!

[ADD]

Just been thinking about power and that...and i realised i dont actualy know why they call it Brake Horse Power! can anybody shed some light please?

thank you

[Lewis]

James Watt, who did quite a bit of work improving steam engines back in the 1700's, needed a way to measure their output. Watt used a common reference, the horse, as the basis for his calculations (like the inch was based on the width of a man's thumb). The exact process he followed to find out what a horse could do is open to speculation, everyone seems to have their own favorite story, but the end result was: 1 horsepower = 550 foot-pounds per second, which means, in Watt's calculations, a horse can lift 550 pounds one foot in one second.

 

There are only seven base units of measurement: distance, time, mass, temperature, electric current, amount of substance and luminous intensity. Each unit can be determined by scientifically reproducible results (no more horses and thumbs!) and all units and standards used today can be derived from those basic seven. An international system, SI, maintains the agreed upon standards for all of these basic units.

Horsepower conversion formulas

The neat thing about defining a reference point with numbers is how easy it is to convert that reference to some other unit of measure.

 

1 horsepower = 550 foot-pounds/second

1 horsepower = 33,000 foot-pounds/minute

1 horsepower = 42.44 Btu/minute

1 horsepower = .7456999 * kilowatts

 

1 kilowatt = 1.34102 * horsepower

 

Horsepower is one measure of power

All of those formulas and conversions are different ways of saying how much work is being done, which is exactly what power is. Power is work done over time.

 

P = W / t

 

where P is power, W is the work done and t is time.

 

Watts are the more common term for measuring power which is why the conversion to and from horsepower is good to know. One watt is 1 joule/second. And that can be converted to ... well, you'll have to do the rest of that research yourself because we could go on forever.

 

A few more horsepower details:

There have been a few different horsepower rating systems over the years. The old "SAE horsepower" is no longer used because it gave a misleading number due to the fact that an engine was tested without any auxillary items installed like alternators, air cleaners or fans. Since 1972 the "SAE net horsepower" is used to indicate the engine was tested with everything in place.

 

Recently, the Society of Automotive Engineers (SAE) released a new testing procedure, J2723, to determine horsepower. The new 7.0 liter LS7 engine for the 2006 Z06 Corvette, is the first engine certified under the new procedure. The output of the LS7 is certified at 505 horsepower at 6300 rpm and 470 lbs.-ft. of torque at 4800 rpm.

You will also hear the term "brake horsepower" (bhp) which is the power measured at the crankshaft. In the very early days, a carefully measured braking force was applied to a drum being driven by the engine in a 1:1 ratio. Now the brake is a dynamometer driven by the engine but the old term remains.

 

"Rear wheel horsepower" or more frequently today, "Horsepower at the wheels " is just what you would think it is, it's the horsepower available at the drive wheels. Since the driveline between the engine and the wheels uses some of the engine's power, there will be less available to move the car, truck or motorcycle. This number is one of the best comparisons since driveline losses vary from vehicle to vehicle.

[ADD]

thats brilliant thank you matey.....im gonna read that a little slower and try to understand it this time

[SuperSupra]

James Watt, who did quite a bit of work improving steam engines back in the 1700's, needed a way to measure their output. Watt used a common reference, the horse, as the basis for his calculations (like the inch was based on the width of a man's thumb). The exact process he followed to find out what a horse could do is open to speculation, everyone seems to have their own favorite story, but the end result was: 1 horsepower = 550 foot-pounds per second, which means, in Watt's calculations, a horse can lift 550 pounds one foot in one second.

 

There are only seven base units of measurement: distance, time, mass, temperature, electric current, amount of substance and luminous intensity. Each unit can be determined by scientifically reproducible results (no more horses and thumbs!) and all units and standards used today can be derived from those basic seven. An international system, SI, maintains the agreed upon standards for all of these basic units.

Horsepower conversion formulas

The neat thing about defining a reference point with numbers is how easy it is to convert that reference to some other unit of measure.

 

1 horsepower = 550 foot-pounds/second

1 horsepower = 33,000 foot-pounds/minute

1 horsepower = 42.44 Btu/minute

1 horsepower = .7456999 * kilowatts

 

1 kilowatt = 1.34102 * horsepower

 

Horsepower is one measure of power

All of those formulas and conversions are different ways of saying how much work is being done, which is exactly what power is. Power is work done over time.

 

P = W / t

 

where P is power, W is the work done and t is time.

 

Watts are the more common term for measuring power which is why the conversion to and from horsepower is good to know. One watt is 1 joule/second. And that can be converted to ... well, you'll have to do the rest of that research yourself because we could go on forever.

 

A few more horsepower details:

There have been a few different horsepower rating systems over the years. The old "SAE horsepower" is no longer used because it gave a misleading number due to the fact that an engine was tested without any auxillary items installed like alternators, air cleaners or fans. Since 1972 the "SAE net horsepower" is used to indicate the engine was tested with everything in place.

 

Recently, the Society of Automotive Engineers (SAE) released a new testing procedure, J2723, to determine horsepower. The new 7.0 liter LS7 engine for the 2006 Z06 Corvette, is the first engine certified under the new procedure. The output of the LS7 is certified at 505 horsepower at 6300 rpm and 470 lbs.-ft. of torque at 4800 rpm.

You will also hear the term "brake horsepower" (bhp) which is the power measured at the crankshaft. In the very early days, a carefully measured braking force was applied to a drum being driven by the engine in a 1:1 ratio. Now the brake is a dynamometer driven by the engine but the old term remains.

 

"Rear wheel horsepower" or more frequently today, "Horsepower at the wheels " is just what you would think it is, it's the horsepower available at the drive wheels. Since the driveline between the engine and the wheels uses some of the engine's power, there will be less available to move the car, truck or motorcycle. This number is one of the best comparisons since driveline losses vary from vehicle to vehicle.

 

 

Just a simple "because it is so there" would've been sufficient I think.

[AndrewOW]

I found that very informative, and thanks to Lewis for his effort

 

I just now want to know how I can increase the torque output in my car!

[SteamAhead]

Cheers ADD for asking that question & Lewis for his informative response.

Not sure about others, but I'm no tech head myself, so sometimes find it a little embarrassing to ask (what some may consider) a stupid / simple question.

 

I will also have to read your response a little slower though