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
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).
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.
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!
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.
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
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.
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.
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~~!!
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 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.
Agree, I also feel I want to cringe. I graduated in Europe and moved to the USA and really feel the level of understanding science in America is way below Europe for the average people. I might be wrong, but my guess is that high school physics in the USA is seriously handicapped by having all these ancient units involved complicating what could be much simpler to understand and remember formulas. Many people ask where that 5252 number comes from and you can find people who even believe 5252 RPM is some magic ideal RPM for an engine, for example. Ironically, this particular video is actually showing a confusion between a pound force and a pound weight. When you specify a torque using foot pounds, the "pound" is not a pound weight but a pound force (like Newton Meters is torque in the SI system). However, in the video the rope is pulling a 200 pound rock. Thus reality is the video is equating pound force and pound weight, These are units that mean completely different things and no, a 200 pound force can't lift a 200 pound weight object on standard earth gravity as the two forces (rope vs. gravity) will just cancel out each other. You need MORE force to move the rock and the more you have the faster you can ACCELERATE the rock: a = F/m = (Fr - Fg) / m = (Fr - m x g) / m. If Fr = Fg nothing happens (Fr: Rope force, Fg: Gravity force). If gravity g is on the moon, the rock will come up no problem :-) So why are nobody saying the example of this video in actuality won't work due to inadequate pulling force?
Nice vid.. I always cringe a little when people act like Torque is what makes for faster cars, not horsepower... Even high profile car guys like Jay Leno of guilty of this fallacy.. But it doesn't take much to realize that this mindset is erroneous.. After all, if torque was more important, short shifting ( thereby keeping it in peak torque) would be the fastest way to accelerate, but no, everyone knows that revving it out to the top of the power band (Where torque falls off and HP peaks) is faster. Furthermore, if torque was king, diesels would be the best choice for fast cars, as they produce massive amounts of torque. With less HP.. But no, it's gasoline engines, which usually produce more HP than torque, that are the choice for the fastest cars. And yes, I know those highly modified diesel trucks are quick.. But take a similarly sized gasoline engine, and throw similarly big boost at it is see what happens.. that's right, you'd have a MUCH faster truck!
i would argue that, a car with great horse power but only up in the higher rev range would loose to a car that can pull hard quickly using superior torque, to a point. its ability to reach max power is more accessible but will loose top end speed as a result. on a tight twisty track torque wins, long open track racing, hp wins.
Savantjazzcollective That's a good point.. And in a drag race, torque would take it off the line and in the 1/8.. But in the quarter, or full mile, you'd want the HP
one could argue that transmissions do torque multiplication and short shifting will cut wheel torque by a lot, so even if the engine is not at it's optimal torque range, the torque multiplication of the gearing more than makes up for the falloff. such as in this graph: www.rx7club.com/attachments/3rd-generation-specific-1993-2002-16/73345-high-revs-myth-fact-gears-jpg.jpg think of it like mountain bike gears: the higher the gear, the faster you can go, but it's harder to pedal. so sometimes it's better to leave at a lower gear and pedal faster, even if that's not where you're most comfortable .
bliglum Yes! "It's fast cuz it's got sooo much torque" irritates me to no end. I try to explain that what they are sensing in their butts is the fact that their diesel or large displacement engine reaches its maximum power at a relatively low RPM, but that just returns blank stares.
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
the rope is attached to too big of a wheel, it's suppose to be attached to a wheel that 6.2 something feet in circumference where as the wheel drawn is like 12.4 feet and thus the engine would stall.
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.
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?
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
The cars tires WILL spin if they aren't on the ground. Also, it takes much much more torque than that to move a car. In the neighborhood of 1000 ft lbs. However the engine doesn't supply this, the toque is multiplied by the transmission at the cost of speed.
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.
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?
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 ?
And what happens if the force delivered is higher than the weight of the rock? Would the rock accelerate (and hence engine speed increase) to the point where the force produced is equal to the weight plus the increased friction?
If the force delivered is greater than the weight of the rock, then the rock will just be pulled up faster. I don't see why the engine speed would increase and I don't know why there would be increased friction.
If rock's going to be pulled up faster, then the engine has to increase speed because they are connected. And friction would increase due to higher drag faced by the rock, and because the engine parts would be moving faster in the oil in the engine. This site (en.wikipedia.org/wiki/Engine_efficiency#Friction) also says that friction will increase due to inertia.
Big Boss Yes the RPM would be greater when this occurs. The increased drag is negligible unless the speed of ascent is very fast. The end result is a rock that is able to be pulled up faster.
Let me ask just a question.So if HP is Torque x RPM/5252 why would the engine pull a rock for example with 200lbs faster than a 400lbs one if for example the torque is 400.I thought that if a motor produces 400 torque on 1000rpm it doesn't change the time of pulling a 200lbs rock or a 400lbs rock,the time has to be the same.I mean the time and the power should be constant only the work is different if you pull up a 200lbs and a 400lbs with an engine like that.Or did I understand it wrong?
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.
I realize this is true: If you don't understand what is force, mass, speed, acceleration, energy (especially kinetic energy) and how these things behave e.g. conservation of energy...don't bother to understand torque and power cause you won't really get it right.
does increasing your engine displacement also increase your maximum engine rpm itself not including the transmission just the crankshaft revolution per minute? hope you notice this (just a noob question thank you guys and happy holidays)
I don't know if I fully understand your question, but there is a lot of engineering into what makes an engines max RPM, just increasing engine displacement isn't likely to increase the max RPM, it is more likely to decrease it because now the piston will take longer to complete one stroke.
+Myrianne DeversRimpel These types of questions are difficult to answer because I would really need to see the entire torque curves. Having good acceleration means having high torque throughout a wide range of RPM's. Also some cars output more torque on the bottom end of the RPM's, others on the top end. Cars with bottom end torque would be ahead in the beginning of a race, while cars with top end torque would pull ahead towards the end of a race. I would need to take all of this into account before accurately answering the question.
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.
What happens around 2:20 for example, if the weight was 205 lbs? Would the motor stall or would it just slow down and take a couple of seconds longer to lift it to the top?
Surely with 205 pounds the engine will stall assuming the engine's peak torque is what is specified in the video. But it will stall anyway for other reasons. This video doesn't represent a real-life scenario at all. Some examples: 1. The available torque, assuming this is maximum torque of the engine, provides a pulling force that equates the gravity force of the rock. There is zero force available to actually lift the rock even with 200 pounds. 2. Any mass needs to accelerate to get to any speed and during that acceleration, you actually must expose the engine pulley for more torque than the engine can do with . As item 1, this means the rock will never move. 3. The rope will have a significant weight considering the 6283 foot length. This adds to the weight of the rock. And when the rock is at the ground, the weight of the rope will be maximum adding to the problem #2. 4. As more rope is accumulating on the pulley, it's hard to imagine a rope and pulley not causing the rope to accumulate in multiple layers increasing the effective radius and thus reducing the effective force on the rope. 5. As the rock is pulled through air, the air drag will act against the rope's pulling force. This equates more torque needed for a particular speed. 6. A clutch mechanism is needed to allow the engine to get started without the load. 7. A transmission is needed to allow the setup to produce the additional torque required to raise the rock. 8. Something needs to slow down the rock when it hits the top at the 71mph speed. An electric motor is much superior in lifting stuff as it can do the work without clutch+transmission and allow more precise control of torque and RPM e.g. as you will find in elevators.
I have a question and I have a difficulties to put this question correctly. I'm gonna try. If my car has max torque at 1900rpm (turbo diesel engine) and max power at 4000rpm, my turbo is pulling the best from 2500-3000rpm and then it loses acceleration appreciably. What is the point of max power at 4000rpm or torque at 1900rpm if I can't sense neither of those?
Honestly, the only one that really matters is the max power. That is the one you will really be able to "feel" because that is what causes acceleration. Max torque is more of just a benchmark metric.
I think there is a little mistake, when trying to lift the 400 lbs another socket should be placed in the same shaft of the bigger socket, because it is not possible to lift it from that socket
I just had this problem, is it true that if you have a 200lb rock and an engine that produces 200ft-lbs and has a one foot diameter fly-wheel or whatever... don't the forces just cancel out?
Listen to me, speed is how fast you run. Muscle strength is how much you can carry when you run. Horsepower is a unit of power and speed is something else. You can imagine a super tanker sailing at 30mph with an engine of many many times more horsepower than a race car driving 200mph. In fact, I could also argue in this way that "horsepower is how much you can carry" LOL as I just did with this example. But that would be equally wrong. These analogies are usually wrong. It's better to look at horsepower as a unit of work per second of time. If you work hard physically you are producing more horsepower than if you are reading a book, for example. And if you hold a book in a stretched arm and add another of the same book, you just multiplied the torque with two.
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
Well the reason I ask this question is because , I'm trying to decide on which is the best power plant for me... On one hand i have a 30.5 cc 8.2 hp engine..... On the other hand i have a 34.5 stroker ( they emphasize a lot on compression and squish factors with the) 7.5 hp engine, boath engines are modifed & race ported.... They went the extra mile on the piston work with the 7.5 hp (cat 5 mfg) engine.... The overall objective is to move this 43 + pound car at its fastest ( with authority) .... I am told TORQUE will be my new best friend & TORQUE is key on take off and coming out of the corners.... I am told by this particular person that they have this 7.5 hp cat 5 mfg engine on their car(losi 5t) and it lights up the tires from beginning to end and that I will be very happy with that engine... The 30.5 cc 8.2 hp O.B.R engine is good from what i red as well..... I'm not trying to buy a name I'm trying to buy true performance & the most bang for my buck....
can cany one explain to me @0:35, why does horsepower increase for a fixed car model ? isn't hp for a car a fixed value? also shouldn't torque decrease as rpm increase??
Nice video but in actuality using a setup that can generate a maximum of 200 pound of pulling force (on the rope) to lift a 200 pound weight of rock is doomed due to gravity and pulling force just canceling out each other. The rock will go nowhere. It's a bit like starting a car in 5th gear on a climbing road (where gravity has to be overcome). Your engine will stall and you will never get anywhere. Check it out. That's why you need to get started in a lower gear that provides adequate headroom of torque to get the car moving.
Torque equates to Force X Distance and the unit of imperial imperial measure lbf-ft.... Ft-lbf is the measure of work done and is distance X force.......
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)
So if you have an engine with massive torque, like over 1000lb/ft and you put it in 2 cars, one which weighs 2000kg and the other 1000kg. The cars are identical (same gear ratio, diff ratio and wheel diameter) except for weight. If the engines make the same horsepower then the weight of the cars shouldn't affect acceleration, right?
The 5252 comes from the dimensional units of torque and horsepower. 1 hp is 33,000 pound-feet per minute. Torque is pound-feet and since it's rotating you must take the circumference (1 revolution) into account (C=2*pi*r). This is why he had to choose 6283 feet as his cliff height (1000*2*pi) which makes the task take 1 minute. 33000/2*pi = 5252.11
QwazyWabbit No this is not quite right, (almost). I have made a pinned comment deriving the HP equation from scratch, please go to the video comments and take a look.
MattsMotorz Good explanation. Yes, it's due to the angular velocity of the torque applied through the radius, which was set at one foot. I chose circumference to link it to your model. Your new explanation is better. (It's the conversion factor of rpm to "feet of displacement per revolution".) ;)
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.
Great explanation, thank you
MattsMotorz I'm more confusing???,...... I'm not the mett guy's here 😔😔😢😢
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 : )
I just added a "short answer" for people not into the math.
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
The short version for simple people like me:
Torque is how much work you can do, horsepower is how fast you can do it.
actually the other way
MrSotko Gaming
no torque means no movement. movement=work.
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."
Yes, this is correct.
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
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
I like it!
thank you
thank you
hahahaha its a giraffe
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).
I have no idea why people still use lbs and feet for measurements, and at this point I'm too afraid to ask
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.
tyler t Torque in Nm x Rotational speed in radians/second = power in watts, no conversion factor required.
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.
Because 'murica
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!
Cait Bittner Awesome! Glad it helped you out!
nice vid but R.I.P headphone users at 5:26
thanks for the warning :)
+Lithoushine I'm about to angry, but he's shared knowledge. What can I say. Lol.
+Lithoushine Lol sorry I should have realized when I was editing. Haha (super late reply!)
+Lithoushine y did i fast forward to 5:26 :( i must b one of dem car crash gawkers
you know you spelt realised wrong
This is the clearest description I have found so far for torque versus HP. Thank you :)
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.
best explanation ever. As a sort of gear head iv'e always known of horsepower and torque but never knew the relationship between the two. Thank you
+fredy velandia Thanks for watching!
That was an excellent depiction of the the relationship between two often misunderstood units of engine measurement. Thanks
Definitely one of the better explanations on UA-cam.
Awesome example !!!
I always used to get confused between these two terms... The way you explained is simply amazing !!!
android1181 Thanks!
I will start rewind your video few times until I understand all the things.
Ghosteriz I feel sorry for you
Annelise Meier let him understand at his pace that doesn't mean he is stupid
Oil Barrel
did you insult him by calling him mongoloid ? those are Asians lol some of the smartest people out there just seems ironic
Wants to make the math easier, uses imperial measurements
Fekillix hp isn't an si unit either you have to do a converaion bruh
Imperial ??? You meant Metric right ??
Horsepower = Torque x RPM
KW = Nm x rpm
You dont need 5252.
Like the rest of the world does.
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
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.
I agree 100%. I am actually going to make a part 2 to this video that says this very thing, and then goes through the 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.
First such lesson I've seen on UA-cam. Thumbs up!
Thanks for the video, I've always vaguely understood the concept about the difference between torque and hp but now I totally get it! Cheers!!
Sam Palmer Awesome! Thanks for watching!
This helped with blowers in HVAC. I worked on a 30 ton unit with a 12,000 CFM blower the other day and was curious about torque and horsepower.
LOOOL why didnt you use metric units, its soooo much easier that way
Puktor But finding out your engine power in KW takes like 10 seconds. Go to whatever car info site your country has and enter your plate number.
horse power is an amount of power needed for lift 750 g to 1 m of height in 1 s. ez enough //EDIT: i meant 750 kg, mistake
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 :)
How is it simpler though?
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.
+Mephles N Thanks for the comment!
MattsMotorz No problem, keep up the good work.
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~~!!
thanks man, your video explained the difference between torque and bhp really well for me
thanks I found this video very helpful
5:27 r.i.p headphone users.
I've been waiting years for an explanation between torque and power! Cheers boss :)
it certainly has helped out now I know what torque and horsepower are. Thank you for making the video
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.
Few people understand the truth concerning the relationship between HP and Torque and that is pretty spot on!!!!!!
+Justin Gillette Thanks for watching!
You solved a great mystery for the common man ...thank you
Ouch so much information in 5:37 minutes my brain is burning. I finally understand it now thanks
this was the best explanation of the ones i have seen
I've watched prob 10 vids on this and this video finally made sense to me.
love the happy rock at 1:39
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.
If by trollish u mean correct
Awesome man,that example was the best thing ,I understood everything.Thanks!
As an european engineerig student, all these units made me cringe...
Metric units make everything so much easier...
Agree, I also feel I want to cringe. I graduated in Europe and moved to the USA and really feel the level of understanding science in America is way below Europe for the average people. I might be wrong, but my guess is that high school physics in the USA is seriously handicapped by having all these ancient units involved complicating what could be much simpler to understand and remember formulas. Many people ask where that 5252 number comes from and you can find people who even believe 5252 RPM is some magic ideal RPM for an engine, for example.
Ironically, this particular video is actually showing a confusion between a pound force and a pound weight. When you specify a torque using foot pounds, the "pound" is not a pound weight but a pound force (like Newton Meters is torque in the SI system). However, in the video the rope is pulling a 200 pound rock. Thus reality is the video is equating pound force and pound weight, These are units that mean completely different things and no, a 200 pound force can't lift a 200 pound weight object on standard earth gravity as the two forces (rope vs. gravity) will just cancel out each other. You need MORE force to move the rock and the more you have the faster you can ACCELERATE the rock: a = F/m = (Fr - Fg) / m = (Fr - m x g) / m. If Fr = Fg nothing happens (Fr: Rope force, Fg: Gravity force). If gravity g is on the moon, the rock will come up no problem :-)
So why are nobody saying the example of this video in actuality won't work due to inadequate pulling force?
By saying 'european' you actually meant EVERYONE except the muricans.
Good vid, makes it easy to understand... btw that's not a rock, that's Ol' Drippy!
Nice vid.. I always cringe a little when people act like Torque is what makes for faster cars, not horsepower... Even high profile car guys like Jay Leno of guilty of this fallacy.. But it doesn't take much to realize that this mindset is erroneous.. After all, if torque was more important, short shifting ( thereby keeping it in peak torque) would be the fastest way to accelerate, but no, everyone knows that revving it out to the top of the power band (Where torque falls off and HP peaks) is faster.
Furthermore, if torque was king, diesels would be the best choice for fast cars, as they produce massive amounts of torque. With less HP.. But no, it's gasoline engines, which usually produce more HP than torque, that are the choice for the fastest cars.
And yes, I know those highly modified diesel trucks are quick.. But take a similarly sized gasoline engine, and throw similarly big boost at it is see what happens.. that's right, you'd have a MUCH faster truck!
i would argue that, a car with great horse power but only up in the higher rev range would loose to a car that can pull hard quickly using superior torque, to a point. its ability to reach max power is more accessible but will loose top end speed as a result. on a tight twisty track torque wins, long open track racing, hp wins.
Savantjazzcollective
That's a good point.. And in a drag race, torque would take it off the line and in the 1/8.. But in the quarter, or full mile, you'd want the HP
one could argue that transmissions do torque multiplication and short shifting will cut wheel torque by a lot, so even if the engine is not at it's optimal torque range, the torque multiplication of the gearing more than makes up for the falloff.
such as in this graph:
www.rx7club.com/attachments/3rd-generation-specific-1993-2002-16/73345-high-revs-myth-fact-gears-jpg.jpg
think of it like mountain bike gears: the higher the gear, the faster you can go, but it's harder to pedal. so sometimes it's better to leave at a lower gear and pedal faster, even if that's not where you're most comfortable .
bliglum Yes! "It's fast cuz it's got sooo much torque" irritates me to no end. I try to explain that what they are sensing in their butts is the fact that their diesel or large displacement engine reaches its maximum power at a relatively low RPM, but that just returns blank stares.
Awesome video. Well explained and easy to understand.
+MattsMotorz Thanks man! I've looked everywhere for a simple explanation of this, and you're the only one that delivered!
+Media_Militia Glad to hear it!
i learn about torque much better now! thank you video :DD
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
haha that's a cute rock
That's nice. How was it?
This video is very much comprehensive thanks a ton for the stuff :)))))))))))
Best explanation by far
4:25 drawing correction
that rope should be much closer to the center of the pulley
Hey, can you explain this? Do you mean there should be another rope, attached closer to the inside of the large wheel?
the rope is attached to too big of a wheel, it's suppose to be attached to a wheel that 6.2 something feet in circumference where as the wheel drawn is like 12.4 feet and thus the engine would stall.
You could use normal units, you know
"Normal" in America is different...unfortunately.
Best explanation ever!... Great vid!..
Any way of getting the metric values? I have no idea how large a foot is and I also have no idea how much a pound is.
Clever way of looking at it... Good job, I like it
Torque gets you moving, horsepower keeps you going!
Torque is a number, Horsepower moves you.
Thank you so much for such a clear explanation.
+Gubceac Nicolae Thanks for watching!
Fantastic video! Helped me understand it better thanks
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.
Very nice video gives good understanding of concept
Nice explanation. Thanks for posting!
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?
Fantastic explanation. Thank you.
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
200 ft-lb of torque at 1000 rpm would break the tires loose so easily... Nice video by the way!
Thanks! Lol yes, not all the numbers chosen for this video were realistic.
how do you figure that. i apply half that putting on lig nuts. the car doesnt spin its tires when i do that.
The cars tires WILL spin if they aren't on the ground. Also, it takes much much more torque than that to move a car. In the neighborhood of 1000 ft lbs. However the engine doesn't supply this, the toque is multiplied by the transmission at the cost of speed.
this was the best explanation
So, a car with 500 horsepower and 400 ft-lb of torque, is better than a car with 500 horsepower and 300 ft-lb of torque, right?
It is impossible to answer that question without first defining "better" and also showing both complete torque-HP curves for both vehicles.
Great video! Very useful. Thanks !
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.
Awesome explanation. Thanks!
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?
Simplified:
Torque: if you have more torque u can lift or move heavier objects
Horsepower: If you have more horsepower you can move weights faster
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 ?
simple, to the point! very good!
And what happens if the force delivered is higher than the weight of the rock?
Would the rock accelerate (and hence engine speed increase) to the point where the force produced is equal to the weight plus the increased friction?
If the force delivered is greater than the weight of the rock, then the rock will just be pulled up faster. I don't see why the engine speed would increase and I don't know why there would be increased friction.
If rock's going to be pulled up faster, then the engine has to increase speed because they are connected.
And friction would increase due to higher drag faced by the rock, and because the engine parts would be moving faster in the oil in the engine. This site (en.wikipedia.org/wiki/Engine_efficiency#Friction) also says that friction will increase due to inertia.
Big Boss Yes the RPM would be greater when this occurs. The increased drag is negligible unless the speed of ascent is very fast. The end result is a rock that is able to be pulled up faster.
Yup. Makes sense. Thanks
Let me ask just a question.So if HP is Torque x RPM/5252 why would the engine pull a rock for example with 200lbs faster than a 400lbs one if for example the torque is 400.I thought that if a motor produces 400 torque on 1000rpm it doesn't change the time of pulling a 200lbs rock or a 400lbs rock,the time has to be the same.I mean the time and the power should be constant only the work is different if you pull up a 200lbs and a 400lbs with an engine like that.Or did I understand it wrong?
How much torque is produced at the other end of the board when the engine is placed like that? Is the board going to break?
Use SI Unit, man.!
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.
I realize this is true:
If you don't understand what is force, mass, speed, acceleration, energy (especially kinetic energy) and how these things behave e.g. conservation of energy...don't bother to understand torque and power cause you won't really get it right.
I would like to know your favorite engines and why..and your fav. car. thx
This helped me a lot .. I was wondering why my Nissan GT-R was reaching top speed slower then my aventador .... (need for speed)(I'm 13 don't judge)
does increasing your engine displacement also increase your maximum engine rpm itself not including the transmission just the crankshaft revolution per minute? hope you notice this
(just a noob question thank you guys and happy holidays)
I don't know if I fully understand your question, but there is a lot of engineering into what makes an engines max RPM, just increasing engine displacement isn't likely to increase the max RPM, it is more likely to decrease it because now the piston will take longer to complete one stroke.
oh i see you have a point there. so the answer is no but it will give more torque. thanks sir! really appreciated.
Horsepower: 300 @ 5800 RPM Torque: 300 @ 1200 RPM vs Horsepower: 330 @ 7000 RPM Torque: 270 @ 5200 RPM typically which car would win in a race?
+Myrianne DeversRimpel These types of questions are difficult to answer because I would really need to see the entire torque curves. Having good acceleration means having high torque throughout a wide range of RPM's. Also some cars output more torque on the bottom end of the RPM's, others on the top end. Cars with bottom end torque would be ahead in the beginning of a race, while cars with top end torque would pull ahead towards the end of a race. I would need to take all of this into account before accurately answering the question.
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.
The face on the rock is gold.
What happens around 2:20 for example, if the weight was 205 lbs?
Would the motor stall or would it just slow down and take a couple of seconds longer to lift it to the top?
Surely with 205 pounds the engine will stall assuming the engine's peak torque is what is specified in the video. But it will stall anyway for other reasons.
This video doesn't represent a real-life scenario at all. Some examples:
1. The available torque, assuming this is maximum torque of the engine, provides a pulling force that equates the gravity force of the rock. There is zero force available to actually lift the rock even with 200 pounds.
2. Any mass needs to accelerate to get to any speed and during that acceleration, you actually must expose the engine pulley for more torque than the engine can do with . As item 1, this means the rock will never move.
3. The rope will have a significant weight considering the 6283 foot length. This adds to the weight of the rock. And when the rock is at the ground, the weight of the rope will be maximum adding to the problem #2.
4. As more rope is accumulating on the pulley, it's hard to imagine a rope and pulley not causing the rope to accumulate in multiple layers increasing the effective radius and thus reducing the effective force on the rope.
5. As the rock is pulled through air, the air drag will act against the rope's pulling force. This equates more torque needed for a particular speed.
6. A clutch mechanism is needed to allow the engine to get started without the load.
7. A transmission is needed to allow the setup to produce the additional torque required to raise the rock.
8. Something needs to slow down the rock when it hits the top at the 71mph speed.
An electric motor is much superior in lifting stuff as it can do the work without clutch+transmission and allow more precise control of torque and RPM e.g. as you will find in elevators.
the outro didnt need to be 4 times louder but nice video, very helpful.
exquisitely explained
This was useful. Thanks for sharing.
I have a question and I have a difficulties to put this question correctly. I'm gonna try.
If my car has max torque at 1900rpm (turbo diesel engine) and max power at 4000rpm, my turbo is pulling the best from 2500-3000rpm and then it loses acceleration appreciably.
What is the point of max power at 4000rpm or torque at 1900rpm if I can't sense neither of those?
Honestly, the only one that really matters is the max power. That is the one you will really be able to "feel" because that is what causes acceleration. Max torque is more of just a benchmark metric.
I think there is a little mistake, when trying to lift the 400 lbs another socket should be placed in the same shaft of the bigger socket, because it is not possible to lift it from that socket
Yes you are right. I made an annotation mentioning this in the video.
Great explanation thank you.
I just had this problem, is it true that if you have a 200lb rock and an engine that produces 200ft-lbs and has a one foot diameter fly-wheel or whatever... don't the forces just cancel out?
or am I stupid?
Listen to me. I will explain this so you can understand. Hp is how fast you can run. Torque is how much you can carry when you run. You are welcome
Listen to me, speed is how fast you run. Muscle strength is how much you can carry when you run. Horsepower is a unit of power and speed is something else. You can imagine a super tanker sailing at 30mph with an engine of many many times more horsepower than a race car driving 200mph. In fact, I could also argue in this way that "horsepower is how much you can carry" LOL as I just did with this example. But that would be equally wrong. These analogies are usually wrong.
It's better to look at horsepower as a unit of work per second of time. If you work hard physically you are producing more horsepower than if you are reading a book, for example.
And if you hold a book in a stretched arm and add another of the same book, you just multiplied the torque with two.
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
Well the reason I ask this question is because , I'm trying to decide on which is the best power plant for me... On one hand i have a 30.5 cc 8.2 hp engine..... On the other hand i have a 34.5 stroker ( they emphasize a lot on compression and squish factors with the) 7.5 hp engine, boath engines are modifed & race ported.... They went the extra mile on the piston work with the 7.5 hp (cat 5 mfg) engine.... The overall objective is to move this 43 + pound car at its fastest ( with authority) .... I am told TORQUE will be my new best friend & TORQUE is key on take off and coming out of the corners.... I am told by this particular person that they have this 7.5 hp cat 5 mfg engine on their car(losi 5t) and it lights up the tires from beginning to end and that I will be very happy with that engine... The 30.5 cc 8.2 hp O.B.R engine is good from what i red as well..... I'm not trying to buy a name I'm trying to buy true performance & the most bang for my buck....
good job
Great video! Really good explanation
can cany one explain to me @0:35, why does horsepower increase for a fixed car model ? isn't hp for a car a fixed value? also shouldn't torque decrease as rpm increase??
Nice video but in actuality using a setup that can generate a maximum of 200 pound of pulling force (on the rope) to lift a 200 pound weight of rock is doomed due to gravity and pulling force just canceling out each other. The rock will go nowhere. It's a bit like starting a car in 5th gear on a climbing road (where gravity has to be overcome). Your engine will stall and you will never get anywhere. Check it out. That's why you need to get started in a lower gear that provides adequate headroom of torque to get the car moving.
Torque equates to Force X Distance and the unit of imperial imperial measure lbf-ft.... Ft-lbf is the measure of work done and is distance X force.......
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)
So if you have an engine with massive torque, like over 1000lb/ft and you put it in 2 cars, one which weighs 2000kg and the other 1000kg. The cars are identical (same gear ratio, diff ratio and wheel diameter) except for weight. If the engines make the same horsepower then the weight of the cars shouldn't affect acceleration, right?
It will. The difference is that the load will be greater on the car that weighs more, which will affect performance.
great explanation. thank you.
The only question I have is where did the 5252 come from?
It is just a multiplier for converting to equations into units of HP.
5252 comes from 33,000 lbft / 2pi. The more specific formula would be tq@RPM x 2pi x thatRPM /33,000lbft/min = HP@thatRPM
The 5252 comes from the dimensional units of torque and horsepower. 1 hp is 33,000 pound-feet per minute. Torque is pound-feet and since it's rotating you must take the circumference (1 revolution) into account (C=2*pi*r). This is why he had to choose 6283 feet as his cliff height (1000*2*pi) which makes the task take 1 minute. 33000/2*pi = 5252.11
QwazyWabbit No this is not quite right, (almost). I have made a pinned comment deriving the HP equation from scratch, please go to the video comments and take a look.
MattsMotorz Good explanation. Yes, it's due to the angular velocity of the torque applied through the radius, which was set at one foot. I chose circumference to link it to your model. Your new explanation is better. (It's the conversion factor of rpm to "feet of displacement per revolution".) ;)