gota911

<sigh> <Tim thinks to himself "Self, you really shouldn't ask this question, 'cuz you're gonna get "grilled" (a.k.a "roasted")! But since you don't know the answer and are curious about this topic, I guess you are going to have to endure the "slings and arrows," not to mention the occasional flame thrower, to get the answer to this question. OK, flame suit on! Here we go!">

<"Oh wait... here is a horrible thought.... what if Phil knows the answer to the question? Oh god, I'd never be able to live that down! Well, he didn't know about the "green dashboard thingie" so the odds of him knowing this are 50/50 at best. OK, we're gonna do it!"> <sigh>

I know, this is probably a stupid question as far a most of you are concerned, but why is HP often referred to as BHP, especially in European publications? I know that BHP is Brake Horse Power, but why the "Brake" part?

smackboy1

BHP is favoured by the Brits hence you see them talking about BHP all the time on Top Gear and 5th Gear. In the US we use SAE HP.

Both BHP and SAE HP are measured at the flywheel and do not take into account drivetrain losses. Basically it a measure of the engine output. But due to differences in the measurement standard BHP and SAE HP can be different for the same car; some cars will measure higher BHP and others higher SAE. IIRC this cause some consternation amongst manufacturers a few years back when the SAE HP numbers of some Japanese imports turned out to be lower than their BHP while SAE HP came out higher for some US cars.

The "brake" refers to the way they used to test an engine, they would hook up the crankshaft to a big fluid filled drum to brake it.

BTW, I am not a mechanical engineer, but I did stay at a Holiday Inn Express last night.

discoganya

During my days as a mechanical engineering student, we'd use a band brake dynamometer to measure torque at the end of a shaft. (Horsepower is then simply torque multiplied by RPM). I believe "brake" horsepower comes from the way you measure it.

Ray S

Tim, you are looking at the wrong measure. Once you get the Honda, you'll find that the kids on the Honda board use "SHP".

Some say "SHP" (sticker horsepower) is a somewhat arbitrary measurement, but for many it is the gold standard.

You see stickers can actually increase the laminar flow of air over a painted surface thereby reducing the Cd of a vehicle. This makes the car faster.

Ask yourself, why do race cars have so many stickers? The answer is SHP.

MechanicalEng

BHP means Brake Horse Power, is the power the engine generates on an engine dyno
WHP means Wheel Horse Power, power transmitted to the wheels
in the US we use HP wich in most cases is the same as BHP

michael.s.under

I thought the 47 pound spoiler on the FWD car added the HP. Learn something new everyday! Whoa! Tim lets see that grocery cart! Get yourself a TV dinner and save some cash!

himself

Wikipedia says:
A band brake is a measuring device for loading a rotating shaft and measuring the torque applied to it and is mainly used to determine brake horsepower. In its simplest form an engine is connected to a rotating drum by means of an output shaft. A friction band is wrapped around half the drum's circumference and each end attached to a separate spring balance. A substantial pre-load is then applied to the ends of the band, so that each spring balance has an initial and identical reading.

When the engine is starting the frictional force between the drum and the band will increase the force reading on one balance and decrease it on the other. The difference between the two readings is used to calculate torque, because the radius of the driven drum is known. If the engine speed is measured with a tachometer, the brake horsepower is easily calculated.

The device is generally used over a range of engine speeds to obtain power and torque curves for the engine, since there is a non-linear relationship between torque and engine speed for most engine types.

Wow, a mouthful.

-td

dresler

Wiki also says this:
The term "horsepower" was coined by the engineer James Watt (1736 to 1819) in 1782 while working on improving the performance of steam engines. This occurred while using a mine pony to lift coal out of a coal mine. He conceived the idea of defining the power exerted by these animals to accomplish this work. He found that, on the average, a mine horse could pull (lift by means of a pulley) 22,000 foot-pounds per minute. Rather than call this "pony" power, he increased these test results by 50 percent, and called it horsepower i.e. 33,000 foot-pounds of work per minute.
Under this system, then, one horsepower is defined as:
1 hp = 33,000 ft.lbf/min (550 ft.lbf/s) (745.69987158227022 watts)

Since you will be moving from a Pcar to a Honda, you should probably use not the "pony" horsepower, but, more suitably, the "komodo dragon" horsepower. This is the power needed to haul a geisha laden carrage to the top of mount Fuji in twelve fornights.

gota911

That was good!

rleeq

What's the green thingie?

LVDell

Why is it that people use Wiki as a source? We banned that in the Universities as student's honestly thought it was a "real" source.

gota911

Check out this thread. We had a LOT of fun with this one!

Dash symbol - how to remove the little green 3/4 circle (a.k.a. Green Thingie)