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Horse power is crap!

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Old 06-19-2004, 01:28 AM
  #1  
jefx
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Default Horse power is crap!

That's right, I said it. It's all crap.

How is it that these pocket bikes are 49cc and producing 2.5 Horse Power while weighing 60 lbs and carrying a 200lb man at 30 MPH, while a 10 lb R/C truck at 3.5cc produces 2.5 Horse Power and goes 40 MPH?

The numbers don't make sence!!!!

On top of it, I'm sure that 2.5 ACTUAL HORSES could could pull a Honda in excess of 20 MPH for over a mile, which I'm sure that these R/C engines rated at 2.5 horses could NOT!

HP ratings are derived from the actual power of horses, that's why it's called horse power. These HP ratings of R/C engines is GARBAGE! Although I am impressed at the work these mini-engines do, they don't even come close to the actual power that a REAL HORSE produces. These ratings aren't even realistic in comparison to engines 10 TIMES THIER SIZE!

So what gives?!
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Old 06-19-2004, 01:41 AM
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Default RE: Horse power is crap!

Good point there Jefx !!!!!
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Old 06-19-2004, 03:10 AM
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Default RE: Horse power is crap!

I thought the horse power numbers were just made up by the manuf. anyway
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Old 06-19-2004, 03:32 AM
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Default RE: Horse power is crap!

The difference between our 3.5cc engines and engine much bigger such as the 49 cc engine in the pocket bike is called torque. Torque moves mass. Even though both engines may have the same hp numbers, the torque numbers are what is vastly different. Kind of like comparing an old 150hp LO5 5.0 liter V8 found in a 3rd gen camaro Z28 to a 140 hp 1.8 liter 4 cylinder found in a 3rd gen acura integra. Their hp numbers are almost dead even, but you try and stick that 1.8 liter integra engine in that big heavy 3rd gen camaro and see if it accelerates at the same rate as it would with the much bigger 5.0 liter V8, it would hardly move. The difference between the two is torque, which comes with bigger displacement. The old addage "No replacement for displacement" comes from the fact that torque is the boss when you need to move heavy mass.
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Old 06-19-2004, 03:35 AM
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Default RE: Horse power is crap!

yeah you are right but the diffrence in the Cc. the pistons are bigger they prouduce more power
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Old 06-19-2004, 06:25 AM
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Default RE: Horse power is crap!

Horsepower comes from a formula that IS based on actual horses, but not in the way you're using it in your examples.
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Old 06-19-2004, 06:37 AM
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Default RE: Horse power is crap!

a bigger piston doesnt always produce more power, as had been said, torque is the main factor in how much mass you can move at what speed, generally you can make up for lack of torque if you can get your engine to rev high enough so that it will pull lower gearing up to the same speed.

BMW F1 racing car 2003 3000cc 900bhp @19000rpm

Top fuel dragster V8 turbo 8194cc 6000bhp @8200rpm

The largest diesel engine 'to buy' ( in 2002 ) is the Wartsila-Sulzer RTA96-C turbocharged two-stroke ships engine - the 14 cylinder, 1,556,002 cu. in. ( 25,498 litre ) model produces 108,920 hp at 102 rpm ( 234 cc/hp) weighs 2,300 tons and consumes 1,660 gallons of heavy fuel oil per hour.

taken from

http://www.simetric.co.uk/si_cc2hp_data.htm
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Old 06-19-2004, 07:51 AM
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Default RE: Horse power is crap!

horsepower is just a function of torque over time. it doesn't really even exist, and there isn't really any way to measure it.
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Old 06-19-2004, 08:19 AM
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Default RE: Horse power is crap!

My engine doesn't even look like a horse and real horses couldn't drink nitro fuel so how can you compare them???
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Old 06-19-2004, 08:37 AM
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Default RE: Horse power is crap!

lol
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Old 06-19-2004, 09:19 AM
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Default RE: Horse power is crap!

I think my next R/C will be gasoline powered.
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Old 06-19-2004, 09:21 AM
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Default RE: Horse power is crap!

Not for me. Thoes things are just to big....
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Old 06-19-2004, 10:29 AM
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Default RE: Horse power is crap!

ORIGINAL: cretin

horsepower is just a function of torque over time. it doesn't really even exist, and there isn't really any way to measure it.
What?? Horsepower is rotational force, no more no less. I.e. the ability rotationally to move 33,000 lbs one foot in one minute. Torqe is hp per unit rpm.

T = (Hp X 5252)/rpm

So you model engine may make make 2 hp at 30000 rpm but that is only .35 lb/ft of torgue, a pittance... those engines on those little bikes don't spin very fast at all. possibly 2.5 hp at 1800 rpm which is 2.5 lb/ft of torque.
J~
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Old 06-19-2004, 10:48 AM
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Default RE: Horse power is crap!

Joules. I think he got it mixed up. Torque is just a function of horsepower over time. That is what sets the difference from R/C engines to the mini bike engines (engines like that). It is not the horsepower but the torque.



(^^^Size of the components)
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Old 06-19-2004, 11:25 AM
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Default RE: Horse power is crap!

kinda, hp is force per unit time (33K lb moved one ft in one minute), torque is hp per unit rpm (hp times a constant divided by rpm). I know rpm is per minute but saying they are both per unit time clouds the issue.
J~
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Old 06-19-2004, 02:08 PM
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Default RE: Horse power is crap!

don't forget torque, RPMs, gearing, and horsepower they all add up to give you what you got
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Old 06-19-2004, 02:24 PM
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Default RE: Horse power is crap!

ORIGINAL: joules

ORIGINAL: cretin

horsepower is just a function of torque over time. it doesn't really even exist, and there isn't really any way to measure it.
What?? Horsepower is rotational force, no more no less. I.e. the ability rotationally to move 33,000 lbs one foot in one minute. Torqe is hp per unit rpm.

T = (Hp X 5252)/rpm

So you model engine may make make 2 hp at 30000 rpm but that is only .35 lb/ft of torgue, a pittance... those engines on those little bikes don't spin very fast at all. possibly 2.5 hp at 1800 rpm which is 2.5 lb/ft of torque.
J~

So the ability to move 33,000 lbs for 1 foot in 1 minute all equals 1 horse power?

So my 2 HP nitro engine has the ability to move 66,000 lbs for a distance of 1 foot in 1 minute? That can't be right!

So a 200 HP engine can move 6,600,000 lbs a distance of 1 foot in 1 minute? Do you know how much 6,600,000 lbs is? That's like trying to pull a skyscraper with a pickup truck.
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Old 06-19-2004, 03:09 PM
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Default RE: Horse power is crap!

Im confused
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Old 06-19-2004, 07:59 PM
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Default RE: Horse power is crap!

Its a long explanation which is related to automotive sport.

http://vettenet.org/torquehp.html


Assuming that the units of horsepower in both nitro and real engines are the same (and I am pretty sure they are) then yes your nitro engine would be able to power a small motorbike. Remember that nitro engines have about 10 times more RPM then real sized engines so they would need about 10 times less torque to produce the same horsepower. Also keep in mind that real sized engines are 4 stroke as opposed to 2 stroke nitro. If you compare 2 stroke and 4 stroke engines of the same displacement then 2 stroke will give you roughly twice more horsepower.
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Old 06-19-2004, 08:39 PM
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Default RE: Horse power is crap!

ORIGINAL: jefx

ORIGINAL: joules

ORIGINAL: cretin

horsepower is just a function of torque over time. it doesn't really even exist, and there isn't really any way to measure it.
What?? Horsepower is rotational force, no more no less. I.e. the ability rotationally to move 33,000 lbs one foot in one minute. Torqe is hp per unit rpm.

T = (Hp X 5252)/rpm

So you model engine may make make 2 hp at 30000 rpm but that is only .35 lb/ft of torgue, a pittance... those engines on those little bikes don't spin very fast at all. possibly 2.5 hp at 1800 rpm which is 2.5 lb/ft of torque.
J~

So the ability to move 33,000 lbs for 1 foot in 1 minute all equals 1 horse power?

So my 2 HP nitro engine has the ability to move 66,000 lbs for a distance of 1 foot in 1 minute? That can't be right!

So a 200 HP engine can move 6,600,000 lbs a distance of 1 foot in 1 minute? Do you know how much 6,600,000 lbs is? That's like trying to pull a skyscraper with a pickup truck.
Give me the right gearing and i could pull the moon down, its not as cut and dried as simple power, changing your gearing can effect you apparent torque ratings too.

A low torque, high revving engine can run lower gearing to a higher speed, so it will move the same weight, the same distance, in the same time, as a lower revving, torqueier motor running higher gearing will.
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Old 06-19-2004, 09:14 PM
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Default RE: Horse power is crap!

just buy RB engine and save your self some confusion...LOL

it is all baout mass vs torque and there are many things come to play between them
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Old 06-24-2004, 02:53 PM
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Default RE: Horse power is crap!

Or in other words, horse power determines how fast it will go in a given chassis set up, but it's TORQUE that makes it QUICK ! ! ! ! Makes all the difference in the world how your going to use it, big oval or drag strip, or off road and road course.
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Old 06-24-2004, 04:50 PM
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Default RE: Horse power is crap!

OK, ok. So we all agree, "horse power is crap!"
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Old 06-24-2004, 07:03 PM
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Default RE: Horse power is crap!

Two words
Gear Reduction
Of course a horse can't move 33,000lbs 1 foot on its own
But with the right gearing over time it can easily

Do you think a horse can move 550lbs a foot in one second or 275lbs in .5 seconds?
550lbsx60 seconds equals 33,000lbs

Can't you think abstractly?
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Old 06-24-2004, 08:13 PM
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Default RE: Horse power is crap!

Of course a horse can't move 33,000lbs 1 foot on its own
Sure it could, as long as it was on wheels. Have you ever pushed a car? A car weighs a couple thousand lbs, and a horse is a lot stronger than we are.

Do you think a horse can move 550lbs a foot in one second or 275lbs in .5 seconds?
550lbsx60 seconds equals 33,000lbs
Have you ever seen those strongman contests where they pull busses and trains and stuff? A horse is still stronger than the world's strongest man.
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