ATTENTION EVERYONE WONDERING WHERE THE 5252 CAME FROM!! ********************************************************************************* Short answer: It comes from converting the power equation to Imperial Units. Long Answer: In physics, if one assumes that the rate of angular rotation is constant, the equation for work is: W = F*d where F is the force in Newtons and d is distance in meters. In this case, if we imagine there is a rope attached to the pulley pulling something up, we can write d in terms of the arc length the pulley has traveled. d = r*theta where r is the radius of the pulley and theta is the angle through which the pulley has turned. So you obtain: W = F*r*theta But remember, the torque T is equal to F*r, therefore we have: W = T*theta Okay so now we want to get power. Power is equal to work per unit time or: P = W/t where t is in seconds. This gives us: P = T*(theta/t) The quantity theta/t is the angular velocity w. In other words, it is the amount of angular displacement per unit time. In radians, this would be equal to 2*pi/t. So we get: P = 2*pi*T/t But since 1/t = f (frequency) we have: P = 2*pi f T THIS is the equation for power, in it's raw, SI unit form. To convert this equation (in units of Watts) into horsepower, we use the conversion factor of 1HP = 33000 ft lbf / min This gives: P = 2*pi *f * T /33000 P = T*f /5252 The frequency f is equivalent to the RPM now that the equation is in HP, so we replace f by RPM to get: F = T*RPM/5252 Which is the horsepower equation.
MattsMotorz 5252 is the point where the limit of torque loses to rpm in all engines and begins to drop as rpm Rises, so for example you wouldn't get an engine that is at 8000rpm making 8000 lbs ft of torque it would lose drop of at 5252 : )
5252 is the approximate rpm where torque and hp intersect. I've done the math for engines with set amount of hp and(250, 300, 500, 800) in my automotive tech. class and for each equation its about 5252 rpm where the intersect is
im extremely sorry. i wish so badly i could tell you that you are correct. its just not the case. and i wouldnt want to spread your disinformation and harm humanity. here is my comment from up top to help you. "one of the best examples is the difference between a Harley and a "crotch rocket" a Harley on average has more torque than say a yamaha R6. they will often take off and accelerate faster than the R6. but their horsepower is inferior. the R6 capable of 165mph the Harley even though it has a bigger engine only say 120mph. the crankshaft of the harley is larger. my friend has a sportster (kinda shitty bike i know) but his engine is 1200cc. my bike, the R6, 599cc. he accelerates faster, due to the larger crankshaft and higher torque, but my horsepower is much greater. i think its like 80 some HP on the sportster to 122HP on the R6. my bike will overtake his quickly. capable of more work, just takes longer to do said work."
another way to look at it is with a wrench. a longer wrench has more torque and can take off a bolt easier than a short wrench. the horsepower is you. ever try to use a really short wrench to take off a tough bolt? the longer one turns it easier. length equals torque in a nutshell without the fancy math as described. but the horsepower is kinda determined on your ability to turn it faster. maybe a bad example but gets the point across i guess lol
Lol, yeah it doesn't make any sense. I think it is just so ingrained in us that it would be difficult to throw it away and get used to another measurement system.
This is because English want that their dominance is sustained. Majorly the sophisticated measuring instruments are calibrated according to English Units not SI Units. This also because of the same reason. This in subtle sense helps them maintain their image of super-power among people's mind.
@Flawed Luck, Friend you may see most the instruments used in industries are in English Units.And yes super power thing may be a silly assumption but is a probabilistic one.
There are so many good questions and discussions on this video. Many of the questions have come up a number of times, so I think I am going to make a follow up to this video going into these questions and into more topics of HP and Torque.
I'm slow on the uptake, but your video helped - I now understand the difference between torque and HP. Although, it will be a while before I can say that I really understand it. Thank you for putting me on the right trajectory. Much appreciated.
relate this: tq= hourly wage rpm= hours worked per year therefor, hp=yearly salary it literally is just tq x rpm = hp yearly salary is buying power if you riase your tq or hourly wage but lower your hours worked per year and make the same per year = the same hp hp is what matters... the tq and rpm only matters in application of hp or salary. towing for example... but hp makes a car fast, PERIOD
Just to add to it - the weight of your car is the area of the country you're living in. You can have a high annual salary, but if you live in San Francisco, much more of your money has to be spent on living costs (many trucks have high horsepower that are balanced out by their weight).
Hi - I just started a job selling VW cars (I sold a different brand before this) and I think it is very important to be able to explain engines and performance to customers. Since we offer gas and diesel engines I have been researching how those work, and then wanted to better understand the actual difference between torque and horsepower. I have watched several videos and read a lot today, and this is the video that helped me actually understand the difference and the significance of horsepower. Thank you for making this easier to understand! It finally clicked!
excellent explanation. no being a math jerk but explain the concept as accurate as reading the math itself!! this is a talent. you are able to educate a greater number of audience then those math jerk. thanks~~!!
Lucas Detex si is metric first of all, and there are two types of hp, both metric and imperial. the difference is the wattage output. the eu released a notice stating that car manufacturers can only use metric hp (or euro hp) basically to keep it familair to consumers who arent used to having automobiles rated in watts, since they are now standardizing watts as the power unit. here in the good ol US.Of.A our automakers can still use imperial hp(745 watts, metric is about 735)
Lucas Detex also you can read on any tuning website that 5252 is the approximate rpm that your torque curve amd hp curve intersect lmoa. that is, if the flywheel is 6 inches in radius
There is no relationship between 5252 and any engine tuning logic. 5252 is just a conversion number due to using old English units rather than the SI system of units. It doesn't mean anything more than that. Obviously you have the same number of horsepower and torque at an RPM of 5252 simply because that's what the formula says. Horsepower = (Torque x 5252) / 5252 => Horsepower = Torque. So what? LOL
Nice explanation. It solved my doubts about gearing. I've seen many documentaries with a car strapped to a dyno, in which the operator shifted gears throught the session. I guess my conclussion is it wouldn't be necessary.
I had trouble grasping the differences between torque and horsepower until I did the mathematical derivations for the respective equations myself. The numbers made it far more clear to me than any verbal explanation I'd heard up to that point. Really, with a good understanding of fundamental physics and math it is far easier to understand the nature of the world we live in. It's not terribly complicated but it does take some time to get to a solid level of understanding. Anyone willing to put in the time to learn those skills will put themselves at a great advantage compared to others, even if you use them just to answer your own questions. I wish more people appreciated the value of understanding physics.
This is exactly right. Too many never spend the time to get to the actual understanding. It's better to begin the understanding by not thinking engines and cars cause that just makes it unnecessary complex. When you grasp what is a force, what is a mass, what is acceleration, what is speed, what is energy/work...move to understand what is torque and power. But don't begin with torque and power without understanding the fundamentals.
on the graphic with the pulleys (gear reduction) the rope attached to the rock should be on a 1ft radius pulley which is attached and shares an axis of rotation with the 2ft pulley
NecomNaTo, that really is a bad explanation as gravity is involved in your description of power. The force of gravity varies with latitude and increases from about 9.780 m/s2 at the Equator to about 9.832 m/s2 at the poles. Furthermore, using some average gravity of 9.8 m/s2, the horsepower needed to lift 750 grams one meter per second is: 0.750 x 9.8 = 7.35 Watts = 0.01 horsepower. If you say 100 meters it becomes closer. Or in other words, a 100 horsepower engine can lift an average human body 100 meters in about a second. Not that I will recommend that experiment though :-)
Oh, sorry, my bad, i sincerely meant kg of course. Just a typo. I remember those numbers from reading about James Watt first introducing his new Horse Power unit to the public, he wanted to show people the power of new car engines compared to the strength of a work horse. 750 kg to 1 m in 1 s is something that anybody can imagine. Nice explanation tho :)
Oooooooohhhhhh. I've sat in automotive classes where the teacher has been asked to explain all this and they can't. Great examples and really explains a lot of concepts of how the RPM and power ratings of an engine effect the output.
Great Video man. I always wondered how torque and horsepower were interrelated and when torque is droping at high rpm/s and still hourse power is increasing. thanks to make it understandable. can you make a similar video for diesel engines? and how is that factor of 5252 come in, please explain.
+Syed Abdul Azeem The factor of 5252 comes in because he is using imperial units. If you used Watts, Newton meters and an angular speed in rps (per second) then hp = torque*rps
What happens if the engine produces for example 400 LBS/ft @500 rpm when the rock Changes weight from for example 400 to 200? Will the engine do the job faster?
i kinda want to hear an explanation on 90s dohc honda motors the example is a 1.8 liter engine turbocharged fully built 700whp range but torque is somewhere around 400-450 ,i know those older honda engine are totally not known for torque i just want to hear the science behind it
ok, can anyone tell me? i'm about to buy a bike and it has 12.14 HP @ 7750 RPM, is this a good deal? its 150 CC (HONDA XR-150), will this be a good buy? considering for street (when i'm in city) and offroad while i'm travelling. thanks.
sir .. instead of using that gear if we try to pull that rock(400 lbs) with that small pully of 200 lbs but with more 'rps' wud it not be able to pull ?
I just wanted to weigh in (and hopefully settle) this argument about HP vs. torque, between Matt and ofsoundminds. You're both right, and both wrong, because each of you is talking about a different torque. Matt is correct in saying that HP alone means nothing, because you have to consider the torque produced by the transmission. A 50 HP farm tractor can tow a 500 HP sports car like a toy, because the transmission in the tractor creates incredibly high torque, although at speeds of only a few miles per hour. (As a separate yet related issue, the tractor also has superior traction, which results from the greater mass of the tractor, and better tire design.) Ofsoundminds is correct (in his trollish way) in saying that a higher HP engine can always tow more, IF it is sufficiently geared down. (He failed to explicitly state the "IF" part.) If the 500 HP sports car engine was geared down like the tractor (and put in the same frame with the same tires), it would tow the 50 HP tractor like a toy. The HP determines the potential torque at different speeds, while the transmission gear ratios determine the actual torque. The ambiguity between potential torque (what could be produced with a hypothetical gear ratio), and actual torque (what is produced by the gears available in the supplied transmission) is the basis for this argument. Great video by the way.
Pretty good explanation of a subject which I feel I am close to understanding, but which still kind of puzzles me a little. I'll work on it. One thing that I wish you would explain, here, is if an engine produces "max torque" at, say, 5,000 rpm, why does the torque or twisting force of an engine "drop off"? I would think that it would have more twisting force at 6,000 rpm, and even more at 7,000 rpm . . . (whether or not the engine is capable of spinning the crank that fast is another matter.)
Denys A The reason why, is because the process gets less efficient at higher speeds. The valves can only open and close so fast, the exhaust can only be pushed out so fast, the intake air can only be sucked in so fast and so on. The engine cannot breathe as well at high RPM and your volumetric efficiency goes down and because of this, combustion efficiency goes down, and as a consequence, output power will go down.
This is absolutely great. I have been looking forward to a video that truly explains the Torque / Power ratings on car brochures. A great great help. However, please help me out in the following selection. Vehicle 1: Max Torque - 103 Newton-metre @ 4500 RPM Max Power - 80 bhp @ 6000 RPM Kerb Weight - 1050 Kilograms Vehicle 2: Max Torque - 247 Newton-metre @ 1800 RPM Max Power - 105 bhp @ 3800 RPM Kerb Weight - 1750 Kilograms As per the equations mentioned, HP for Vehicle 1 is 88.25 and that for Vehicle 2 is 84.65. Still, I would need your answer towards which is a better vehicle ?
Rohit Singh One thing you forgot to do was convert from Newton meters to foot pounds. After doing this, you find that the first vehicle has a horsepower of 65.1 and the second vehicle has a horsepower of 62.4. So this is actually an interesting case because the second engine makes more max power right off the engine, but actually has less max power at the wheels due to more losses through the gearing (Assuming that the Max torque measurement is a measurement at the wheels). But to answer your question, it is hard to say. Each vehicle has a max horsepower at vastly different RPM's and there is no information on how it performs at other RPM's. It also depends on what the vehicle is being used for. A car that needs to be able to tow something needs to produce a large amount of torque at a low RPM, but a car that needs to go fast needs to produce a large amount of torque over a wide range of RPM's. So in the end, I wouldn't be comfortable in saying any of those vehicles are better.
Thanks for the analysis. But I still want you to make a decision on which is a better vehicle. Some more info available in these vehicles' respective brochures are as under: Both are used as offroaders in tough Indian terrain, where fuel stations are 1 in a 100 kms stretch. Both are used for towing. However, Vehicle 1 claims to be getting out of mud / slime much easier.
Hello maybe you can help me.. i want to know what determines how much HP there is in an engine? For example, I have have a 125 cc single cilinder go kart engine that produces 40hp but why does it produce 40hp?
what aspects determine how much torque is produced at certain rpm's? eg. why do some engines only have a narrow torque-curve where as others claim to have maximum torque = '300nm @ 2,200-3,600rpm' ?
SO many things. How well the engine breathes, how fast the valves close, literally every aspect of the engine contributes to how much torque it produces. There could probably be entire books on this subject (as I am sure there is)
