Why Do Horsepower And Torque Cross At 5,252 RPM?

[@EngineeringExplained]

Hope everyone's having a wonderful day! If you're watching and confused about what the difference are between Horsepower and Torque, I have a previous video to sort that out: kzbin.info/www/bejne/q16weWepm5qrobs. If you're watching this video and you're thinking, what the heck, math!? We all feel similarly haha. If you're watching this video and thinking, really I just want to see pictures of cars and the sort, here's my Instagram: instagram.com/engineeringexplained/

[@michaelblacktree]

Long story short, it's just a side effect of the math used to calculate power.

[@johannesdatblue4164]

hey the kilowatt formula is wrong i used it on my aprilia rs4 125. . 11nm at 8250rpm 15hp/11kw at 10500rpm

[@Legato-2057]

That was wonderfully pointless. Thank you !!

[@jefft137]

I followed all of this until you lost me. I'm just not saying where that was :) There's a reason why some of us chose law school, like almost failing freshman calculus.

[@ac130ugunships]

hey i have a video idea, and a question that stems from this video. how does the outside tire diameter and potentially the rim size impact haw horse power and torque are delivered to the road to help accelerate a car?

[@lonerider5315]

Put a mic on that marker so we really hear that squeak good

[@boostedprius4707]

is that a new fetish? interesting.. asmr? :D

[@brandonwiebe2647]

Oh yeah, squeak it hard for me baby!

[@chatsash36]

Easy upvote.

[@tbas8741]

The squeaking is turning me on

[@JoseMejia-kg6gi]

Sha Dow I wish I was a marker

[@xcq1]

And if the lines actually cross at 9549 rpm you not only have a metric chart, but more importantly an amazing engine.

[@TG93Handle]

Someone's using a rotary engine lol

[@gsnedders_legacy]

Hah, yes, that was my reaction. "They normally don't cross? o_O"

[@lgsus4209]

I mean hondas have an impressive high rpms dont know why people hate on the well build ones

[@Thlips]

Well. That isn't high at all for a motorcycle engine.

[@GT6SuzukaTimeTrials]

Depends on the bike. Mine redlines at 10,500

[@johnnyboyssite]

As a Mechanical Engineer myself, believe me it took awhile to understand the concepts during the process of obtaining that degree. Curiousity with how things worked along with being a gearhead kept me in play. Its a matter of sticking with it and lots of study. Love the Channel !

[@JBlades88WV]

Where did you get your degree? I'm interested in mechanic engineering but I have no idea of how to get started. I can't afford to go to a technical school and I'm 34 so it will probably never happen.

[@Iffy50]

@@JBlades88WV I'm a mechanical engineer and I don't understand your question. I got my degree from Michigan Technological University. Mechanical engineering is a 4 year degree and is mostly theory (or at least it was when I was going to school in 1990-1994). When I hear "technical school" I usually think of a 2 year community college with practical degrees that will prepare you to be useful in the workforce, but don't involve a lot of theory. By "technical school" do you mean MIT, Cal Tech, Stanford? If so, I agree, that's A LOT of money if you don't have a serious scholarship. Many state schools offer degrees in engineering, total bill will be around $100K if you include everything (tuition, room and board, books, etc)

[@Eduardo_Espinoza]

I can learn the math, but the tests are too quick for me. My hand writing just keeps getting worse, & I can't write small.

[@Farsightful]

So you know his speed equation is extremely over simplified because there is no slip or deformation in his world.

[@05Forenza]

"it's completely pointless"...died laughing there and continued to watch :P

[@esunisen3862]

*presses replay button*

[@andresacevedo347]

Steve Oswald me too! Lol

[@RogerBarraud]

@@esunisen3862 Turns Loop on... :-)

[@devilliersduplessis7904]

I dont see a standardization as meaningless

[@HarrisonCountyStudio]

“There is nothing exciting about it” 🤣

[@derrekchilson8606]

Pointless you say yet I feel smarter after this video...I'd definitely give this channel most informative award.

[@kleinbottled79]

The relationship of power and torque comes up a lot in certain circles, but there is a heap of ignorance being spread at the level of folk lore "Torque wins races." etc. Being walked through the math is helpful to the internet at large. 5250 might be arbitrary; but pointless, this video, was not =D

[@rudyjohn2258]

I feel smarter too! Never quite understood when I was reading car specs what this meant. You satisfied my engineering car/geek question that I have never understood till now! Thanks!

[@therealjohnsmith4811]

So glad you actually put science behind it. So many do not understand tq, hp, and how a dyno works.

[@alantrimble2881]

Different style dynos work differently. An old Clayton water brake chassis dyno works nothing like a modern Dyno Jet chassis dyno.

[@codyramos3200]

Different dyno = different numbers Different dyno operators = different numbers Dyno operator can manipulate the figures to make more hp/tq or less hp/tq as well from my understanding. I've seen this on 2v 4.6 mustang forums .. full bolt on cars don't break 290hp even with cams they barely scratch 300hp without extension work on heads . When someone posts a 350hp or 400hp dyno graph people call them out or the dyno operator out pretty fast.

[@therealjohnsmith4811]

@@codyramos3200 Agreed. A dyno is really just an idea of where one is starting from. Any mods should be measured on the same dyno with the same operator.

[@themindgarage8938]

Unit cancellation is so satisfying...

[@AnitaHandy65]

Looked at comments to see if it was just me that found this satisfying... Evidently not

[@thybigballs]

that sounds painful

[@bcubed72]

That's how you double-check that you set the equation up right.

[@justsomeguywithoutamustang6436]

sexually* satisfying

[@ZajoSTi]

Yes, it is like a full row in tetris. Never gets old.

[@joshhayes3433]

This video is exactly why I love this channel, it's entertaining and informative and Jason is honest about how this doesn't really mean anything :)

[@ludacrisleon828]

Clips like this is why I watch. Im off to spread useless but interesting knowledge

[@raytruant9497]

Ludacris Leon If you understood this video, you would not call this knowledge useless.

[@ludacrisleon828]

Ray Truant I understand but I am not an engineer, mechanic, car salesman or anything. So yeah, for me this is useless but interesting.

[@ploperdung]

@@ludacrisleon828 general knowledge will always come in handy

[@markburkey6371]

@@ploperdung lol, If only this Knowledge counted as general...🤣

[@ploperdung]

@@markburkey6371 knowing about horsepower and torque doesn't mean you have 300 IQ, this knowledge is pretty general, this is just surface knowledge.

[@lukecates5136]

If it wasn't for you I wouldn't know half as much about cars as I do.👍🏻👍🏻 keep it up

[@jackofblades3171]

Luke Cates I went to school for automotive but EE has great refresher courses for people who just want to hear it all again

[@lukecates5136]

Jack of Blades yes, he definitely is.

[@MrTheHillfolk]

He reminds me of my fathers typical conversations, but in a younger brothers body.

[@frankcelestino7816]

This was definitely a mathematic nerd out in which I enjoyed. :)

[@AhmadDanHamidu]

Great explanation. Please do a video on "why most cars develop maximum torque at mid-range RPM instead of at high-range RPM" and "why the best acceleration effort of the engine occurs when the engine is churning-out approximately half of its total power rather than when it's churning-out all of its power." Once again, thanks for all your great videos. Please notify me when you do the video in suggesting.

[@keegentilley578]

That 1st question would be a good video

[@TheBTRGarage]

Never knew this! Now I will have something to talk about at the dyno tomorrow instead of worrying if my BRZ will break 150ft.lbs of torque 😐

[@chiragtrivedi913]

You explain things with engineering basics that's the unique thing about ur channel. Satisfys that inner nerdy engineer in me who wants to know why and how based on facts. Grt job

[@EngineeringExplained]

Happy to hear it, thanks for watching!

[@michalhikrysz]

I've never enjoyed a meaningless piece of information so much.

[@EngineeringExplained]

Haha, happy to hear it!

[@everythingtractors9332]

@@EngineeringExplained ok

[@MrWilliam.Stewart]

Jason is really a wizard, he just chooses to shave his silver beard to go incognito.

[@garrettrainbolt1344]

Gandalf

[@BTCAutomotiveTech]

Funny coincidence, we had been doing an assignment/having a discussion in class about horsepower vs. torque when your last video was published a few days ago. There were a few questions from my students about why you never mentioned the 5252 thing. Well, here ya go!

[@Nikolai18A]

I think it's awesome that Jason's material is being used by educators. While I obviously hold that Teachers and Educators in general have a firmer understanding of the materials they teach, it has been my experience that the concept is oftentimes easier to digest when explained by someone of relative age. Whether this has to do with words or analogues used or not I can't say, but I wholly approve of access to, at least potentially, complex concepts in digestible form; a skill at which our friend Jason seems quite adept.

[@ploperdung]

@@Nikolai18A " I obviously hold that Teachers and Educators in general have a firmer understanding of the materials they teach" He has an engineering degree, he would know more about it than a school teacher.

[@Nikolai18A]

@@ploperdung I disagree in part. Educators are necessarily more engrossed in not only the subject matter, but in breaking it down for others to comprehend. Such things are only possible when a comprehensive understanding of the underlying concepts is present. I don't discount the potential of a "student" understanding better, or more completely; obviously every educator was at one time, a student. But by and large I find that educators grasp the subject matter far more accurately than their students.

[@ploperdung]

@@Nikolai18A i agree with that but i said that the guy on this channel has an engineering degree and that he would understand better than a teacher.

[@Nikolai18A]

@@ploperdung Who, praytell, would have taught him, certifying his degree? Professors; educators. It's one thing to understand the material. It's quite another to understand the material in a way that enables you to accurately relay complex topics to others. That's not often an inherent trait (and I think our friendly neighbourhood engineer has this inherent quality), and is a difficult one to teach in its own right.

[@CameronJamesRose]

Funny, I was looking for this formula yesterday whilst working on my dissertation project. Decided to watch this on my lunch break today and voila!

[@berengerchristy6256]

I found it a few days ago and I'm just some guy. Coincidence? I think so

[@shakti6903]

My car's redline is 4800 rpm😹

[@fmmchannel6365]

is it a diesel?

[@shpyrko]

Your horsepower is not as important as torque!

[@shakti6903]

Faris Muhammad yes

[@shakti6903]

shpyrko i know😂

[@lazydadsgarage]

And thats why your rated torque number is much higher than horsepower

[@ThoolooExpress]

Interesting to note, if you use the proper Si unit of angular velocity (rad/s), kW and N*m should cross at exactly 1000 rad/s.

[@2b134]

that's because a kW is 1000 Watts, if you used Watts you'd have 1 rad/s

[@rainystorm88]

Best way to spend 6 minutes learning something absolutely pointless xD

[@clayz1]

rainystorm88 Hardly pointless. It shows plainly the difference between using different units of measure, which helps any curious person. I submit you are actually very curious.

[@boosted2.4_sky]

If anything it gives people who generally don't think, use, or may find, mathematics hard to understand an opportunity to flip light on... when someone is speaking about something they're generally uninterested in in a way that coincides with something they are interested in... it really helps....

[@RonJohn63]

Math is *never* pointless!!!! :)

[@worldtravel101]

rainystorm88 pointless? NO!

[@ieatass4591]

Maybe you should stick to making those pointless videos in your channel and leave those who are intelligent to these videos.

[@josephjocson1385]

engineering explained your all in one channel for car guys and everyone wants to be involve in automitive tech or industry

[@CarsSimplified]

Always a well-made video. Good to see the whiteboard back in action!

[@EngineeringExplained]

She'll never retire! :)

[@Yathuprem]

Imperial user here , still watches. Nice video ! But in metric 1HP=749W, So how can it become 9549?

[@juzoli]

If your kid hates math, but loves cars, show him these videos, and he will ace all tests:)

[@lolzordje123]

Zoltán Juhász unless its statistical maths 😂

[@juzoli]

Thomas Fooij See his videos for example about comparison of tires. He did multiple runs, and took the average of them. Engineering is also based on statistics

[@geneva760]

Yes - an IMPORTANT factor in effective learning - you need to have a real interest in the topic - then learning becomes FUN and not a chore. (and Zoltan - HA - it should be "...show him or her..." Some girls like cars as well, some boys do not like cars as well - HA)

[@juzoli]

Private Private (Ah, I hate that english is so gender biased, I never sure what is the best expression. In my first language, all pronouns are gender neutral...)

[@geneva760]

Yes - HA - easy to get someone all upset over nothing.

[@toysoldier8947]

should have did a mic drop with the marker and walked off frame, nerd cred

[@LernestW]

I love when formulas are explained in a way that I can grasp. Well done. I learned something and I enjoyed it.

[@KillItandGrillIt]

Thank you for this video I grew up building engines my father was a racer and I learned that a properly designed engine would do as you say but I never understood why till now. No one taught us anything except the bare minimum back then.

[@AzuraiAeon]

God I love this channel.

[@thatoneotherotherguy]

I feel smart!!! I already knew the exacts reasons and maths behind this from engineering school. Always had an interest in both cars and engineering, and it was annoying in my youth not being able to explain to friends that hp and torque are related, and not independent.

[@andrewholaway4113]

Nothing quite like a 6 minute video that ends with "in the end, it's pretty much meaningless but thanks for watching"! Honestly though, it was an interesting video even if the magic number is meaningless.

[@bigb1946]

Pedantic Point: Imperial Units were adopted in the UK in 1825-26. In the US, we use "The United States Customary Units System" formally adopted in 1832 which was mostly developed from the English System (actually the Winchester Standards in use till 1825) There are many significant differences between the Imperial and USC Systems. For example, it takes 1.2 USC Gallons to equal 1 Imperial Gallon. Now the UK and most everyone else use the Units SI (Metric System) while in the US we use both the USC and the Metric System depending on the industry or product.

[@emilau11]

You inspired me to become a mech-e!

[@EngineeringExplained]

That’s awesome to hear, appreciate you watching, and best of luck with your career!

[@trebornoslo1951]

The 5252 rpm figure can be calculated by using a shaft that is 1 foot in circumference and turn it 1 revolution. This means that the diameter of the shaft will be (using inches now) 12 divided by 3.1416= 3.819 inches. The radius of the shaft is 3.819 divided by 2=1.909. then if you apply a force of 33,000 lbs against it you will get a force of 33,000x1.909=63052.2 in lbs of torque on the shaft. Put a lever 1 foot long on the shaft and divide 63052.2 by 12 and you get 5252.1 lbs at the end of the lever. To get 1 horsepower turn the shaft at 1 rpm. So 1 horsepower = 5252 ft lbs at 1 rpm.

[@egeg-nr4qs]

I'm pretty sure the intersection at 5252 (in imperial units) does allow me to make one assumption... When a vehicle's peak power rating is higher than it's peak torque rating, I know it's a relatively high performance engine (or at least that it's power peaks above 5252rpm).

[@metalinvalidmatt]

are all these videos one-takes? maybe I'm not watching close enough but that would be bloody impressive, especially with all the info that needs to be A, remmembered, and B, spoken about in a clear and coherent way, possible that there's a script or some sort being shown off-camera but even so, well done Jason!

[@omttmo]

Best 6 meaningless minutes I spend today. Good work!

[@soilomasbello1156]

In a rotatory system Power is RPM times Torque adjusted by a constant that depends in the system of units used, that is: Power = C x RPM x Torque, where C is a constant. If HP is used for Power and lb-ft for Torque C = 1/5252. From the equation is easy to see that at 5252 RPMs Power(HP) = Torque (lb-ft).

[@levy5867]

Math is your thing, that's the thing that sets you apart from other channels. keep 'em going, It doesn't matter if it's pointless math, or if I get lost halfway of the video, I'll catch up with you eventually.

[@beobe99]

Saw this Video Title a week ago but never watched... Then I started noticing all Dyno Charts meeting at 5252 and it started to drive me crazy!!! So, here I am watching why! Thanks!!

[@kleitos000]

Nice. Just a little tidbit I never thought about before. Cool video.

[@StoneCanyonCreatives]

“It’s pointless, completely meaningless, and uninteresting” he says as I’ve been completely glued to the video in pure interest and understanding😂

[@lukeharry8648]

That's when the VTEC kicks in!

[@DirtyRyda]

"That's when the VTEC kicks in, yo!" Fixed it for ya.

[@wiredforstereo]

Before watching the video, I'm going to hypothesize that it is a mathematical thing based on how torque and horsepower are calculated and it really means absolutely nothing because the two lines are two different things with two different units. Bazinga!

[@Darkninja4256]

At first I was like, "oh God algebra." And then at the end I was like, "oh that makes sense."

[@Whitefang8128]

What algebra?

[@matthesinator]

It's algebra. He's solving equations, which is algebra.

[@fidelcatsro6948]

dont worry just remember your audio is 200 watts!!

[@dingo137]

Indeed, its no more significant than the fact that distance travelled in miles is the same as journey time in minutes at 60mph. True by definition.

[@jimbo2150]

Would it be any more efficient to have smaller pistons working together or fewer larger pistons?

[@anzonix]

Yeah? Like 2.4L 4cyl vs 2.4L V6 perhaps?

[@empi1972gtv]

I'd like to know this as well, although the bore to stroke ratio will play a big factor. Difficult to have an apples to apples comparison, I would presume. I'd also be curious to know if adding say 2 cylinders to an inline 4 (all else remaining equal) would increase power by exactly 50% or would there would be a greater increase by having more firing events per revolution...

[@gamerbidd]

It’s got to be 4 cylinder hasn’t it? Since there would be less parts to spin and move, less bearings causing friction, less pistons moving causing friction (admitted since it’s all oiled so makes minimum difference but surely does still make a difference)

[@Derpuwolf]

Anton more like 8 2L cylinders vs 4 4L cylinders. That's what I think he meant.

[@jimbo2150]

Yes, or maybe even 20 smaller pistons? Is there any difference in getting the ignition to happen in smaller or larger chambers or could more smaller pistons be more efficient, lose less heat, or produce greater combined power perhaps? Basically, is there a specific reason for pison sizes and the 4/6/8 number of pistons in most vehicles?

[@matthewkuhl79]

It can't be meaningless: you made a video explaining the math and i watched it!

[@andraslibal]

Engineers. Putting two different units on the same axis.

[@crashTestGuru]

It's just 2 graphs in 1

[@andraslibal]

@@crashTestGuru then put two y axes with different units on them to the left and the right.

[@adriandurn5903]

@@andraslibal there's no need to use separate y-axes if they're similar enough numbers. Them not being the same metric doesn't make a difference, in SI units you would need two Y-axes to make it readable but in imperial units a 100 ftlb engine produces close enough to 100 hp for it to not matter and they scale at that. If you want to get accurate then you shouldn't have two separate y-axes, but two separate graphs instead, one for torque one for power, then each graph can have two y-axes, on in imperial and one in metric, or vice versa.

[@MitzvosGolem1]

Some units are " dimensionless" in physics engineering equations .

[@wombat4191]

It's so awfully convenient

[@SaverGC3]

Up until now, I never did know how horsepower was calculated; but, I was curious. Thank you.

[@alessandro5693]

I appreciate that you include the conversion in the metric system. Nice video, love this channel!

[@johngreen8062]

In metric that would be P=F*v=F*2*pi*r/t=T*2*pi*f -> P/T=2*pi*f. So, the ratio is proportional to frequency and P [W] and T [N*m] are equal in numerical values at 1/(2*pi) [Hz].

[@DanielJaegerFilms]

My brain hurts now

[@f-j-Services]

Hi!

[@flipmode74]

LOL, it means absolutley nothing but hes smiling from one cheek to the other after explaining it. Thats why i like this channel, becuase he likes what he is explaining to us.

[@BrainTimeOut]

But european often use other Units than kW like bhp in england or PS in germany

[@EngineeringExplained]

Yes, you can tweak the equation for any unit, and the RPM will be different.

[@adrianburmester1159]

Well, PS is Pferdestärke, wich is the direct translation of Horsepower

[@BrainTimeOut]

1 PS is not 1 Bhp its like 0,98 bhp

[@TheBokChoy]

Those are very close to imperial Horsepower so the intersect value would be very similar either way, and he did mention in the video that units don't matter, since it's an arbitrary point anyway

[@tominotopia]

PewPewLazors but 1 PS is 1 HP

[@pkpotate]

I've watched a lot of engineering and technology fellows try and explain stuff. They tend to enjoy doing stuff like paid promotions and a lot of weird drama can tend to get involved. I've always enjoyed your channel because your one of the few channels that sits here and goes. LOOK! THIS IS AN OPINION! ok, now that that is out of the way, here are all the base facts, regardless of my opinion, and how they stand. When your opinion is interjected, you will straight up say, I know my opinion is silly, so here are the facts, I still have my opinion, but I'll let you make your own opinion. You ALWAYS give the facts and even correct yourself when you make mistakes (which is FAR fewer then most channels) and you do an excellent job with how you present yourself. I love it because I know I can get EVERYTHING unbiased from you and it's all just number crunching and realistic stuff with you. Thank you for being awesome and keep doing what you're doing!

[@speelydan]

So basically, they cross at 5252rpm solely because the definition of "horsepower" is based on some guy's arbitrary decision to settle on 33,000 for the amount of work his horse could do in a minute - the calculation of which was based on his arbitrary definition of "work". How did Europe define the kW to wind up at 9549rpm?

[@festol1]

1 HP = 745,7 W

[@okaro6595]

One metric horse power is 735.49875 watts.

[@festol1]

@@okaro6595 Indeed Mechanical (or "imperial") ~ 746 watts vs Metric ~ 735 watts.

[@bruceeverett5372]

"and it's completely pointless" sounds so much better than "because I said so" ( 9th grade math teacher's fav) --Like your style man!

[@joedesalvo3316]

Praise Be

[@EngineeringExplained]

Under his eye.

[@ast5515]

Mad Max Chumbucket reference?

[@alexzander1839]

Joe DeSalvo, to God.

[@m.b.82]

I always thought it was a fallacy when people say the crossover on the graph is your ideal shift point. To me it just seemed like a product of scales and units of measurement that mean nothing in particular. Now i know for sure lol

[@nobodynothing6551]

You actually want to shift at a point such that engine rpms do not fall below peak torque when upshifting during a drag race. If you can stay at peak power that's even better.

[@zamx96]

My redline is 5400 so does it still cross at 5252?

[@ATomatoIsAFruit]

Yes

[@Vvince68]

Yes.

[@zamx96]

How?? 😂

[@Napster60]

It would have if your engine would survive that many revs. Sounds like a diesel. Basically your torque and horsepower curves are on the way to Crossing but your engine runs out of RPM before they do.

[@zamx96]

Napster6 it's a jeep grand cherokee 5.7 v8 2009

[@njx1993]

I think the part where you said that the scale of the graph changes the visual representation of where horsepower and torque intersect on the graph without mentioning that regardless of that situation as soon as your RPM is 5252, the number representing horsepower and the number representing torque will be identical. I think that part might confuse some people.

[@leenux1707]

it's not different for every engine ??

[@EngineeringExplained]

Works for any engine; the "why" is explained in the video. :)

[@brenoakiy]

no, but it's a meaningless number...

[@leenux1707]

I ask because it don't work on my cars ... but they are not stock ...

[@TheBokChoy]

It's a mathematical proof. Therefore it's true for any value. So no every engine is the same, and will cross over at that point

[@graigchq]

The only thing Jason didn't emphasise enough for the non-mathematical amongst us was that this number is DIRECTLY derived from the fact that one horsepower is 33,000lbft/min. He explained it above, but your question intimates you didn't hear that info. Had James Watt decided that one horsepower was 40,000lbft/min then the 5252 number would be 40/33 times bigger, and the dyno graphs would cross at 40,000/2pi = 6366 rpm (to 4sig.figures) Again, the silly part of all this is that its arbitrary to say the least. In Europe we mix Horsepower for Power units and Nm for torque, and don't see the graphs cross because they are not dimensionally consistent.

[@justincase9638]

Two eyeballs staring back at you...with one eyebrow raised. Well that changed my thinking.. I was under the impression that the intersection of HP and Torque was the sweet spot for efficiency and power? Now you tell me it's nothing - nada - nope! I'm left feeling empty... In fact it seems intuitively deceptive to represent Torque and HP on a graph like this because our attention is drawn to the intersection point - but it represents nothing?

[@EngineeringExplained]

Correct.

[@bwxmoto]

Because horses

[@mattypoo216]

Your teachings could have caught my attention in high school and I probably would have finished instead of dropping out getting a job and my GED a year before I was supposed to graduate

[@Jerrypintoswe]

Wait, what?

[@QuattroRMT]

?

[@dcg748]

Wait, Watt?

[@urano4810]

Wait, horsepower?

[@autophyte]

If you run any engine on a dyno, the readout at 5252 RPM for torque( in Ft/lbs) and horsepower (in HP) will always be the same number. This is because of the formula for Horsepower, is always (torque X RPM) divided by 5252. So, if your engine develops, say, 375 ft/lbs @ 5252 RPM, it will also be producing 375 HP @ 5252 RPM. , as the 5252's on the top and bottom of the equation cancel each other out, leaving just the torque figure, which is then also the HP figure. Try it on any rpm and torque number, look at the readout from any dyno.They will always be the same at 5252 RPM. It is not just a random number, it is the correct torque and horsepower figure. All you (or a dynamometer) can really measure is twisting force - (torque). Horsepower is a theoretical figure worked out by the formula, using the torque figure and RPM as variables.

[@bobriley000444]

is this guy 25 or 45?

[@fidelcatsro6948]

33.5

[@nasuh_won]

Both

[@urano4810]

Yes

[@NetRolller3D]

Fun fact: the metric crossover point of 9549 *is* actually meaningful. It's the conversion from RPM to angular velocity (1 radian per second is 60/2π RPM, and 60/2π is about 9.549) multiplied by the 1000 to account for the "kilo" prefixed power unit.

[@NetRolller3D]

In other words, 9549 RPM is 1 krad/s.

[@patearacingteam]

Where does Nm*rpm/7127 come from it seems to give the right number and when using the same formula and dividing by 9550 doesn't give hp? Got it it gives Wats when divaiding by 9550 :)

[@Vandebirt]

3rd view before the hundreds of thousands!!!

[@ET_Don]

You brought back some fond memories. In the late 80's I was a Dyno Tech in the engine overhauls shop at a Detriot Diesel dealership. My job was to take every engine that had a fresh out of frame major overhaul, do a break in run, then full load dyno tune (someone else ran the in frame overhauls on the chassis dyno). I vaguely recall using the Torque X RPM ÷ 5252 equation to figure HP because our dyno only displayed torque. Thanks for this, and all your other videos. Subscribed!

[@jonathonhebert7042]

I would've ran the torque output graph through excel and made a HP graph using the same formula ;)

[@lavix5]

And we learned nothing today :D

[@rotorblade9508]

lavix5 that’s your problem, if you already new that why did you expect to learn something new?

[@flik02]

As a car guy I do actually find this video relevant because it shows why the intersection at 5252 can be used to validate dyno settings for accurate readings. Temperature, elevation, humidity, and other settings can be altered, either intentionally, or by mistake to produce false dyno readings. Showing that the intersection is the mathematical constant, is a simple way to quickly verify the validity of dyno result, particularly in advertising.

[@BPEKSupraInteractive]

A meaningless video. Thanks, Jason! LOL

[@blamb42]

I got a little lost in the math but the fact that it has to do with the scale of units makes perfect sense. Thanx.

[@PauloAlexandreOgliani]

Jason, you have the power to make me feel smart because i understood your clear explanation.

[@michaelharrison1093]

I can remember working of the instrumentation of some very old engine dynamometer - pre digital instrumentation. The RPM measurement was made using a permanent magnet generator hence the output voltage increased as a function of RPM which was indicated on a large analog volt meter that was calibrated in units of RPM. The torque was measured with a torque reaction spring and the amount of reaction was measured using a variable resistance unit that was configured as a variable voltage divider. The input to this variable resistance divider was fed a DC voltage and the output of this variable resistance divider was a voltage that was also used to drive a large analog voltmeter. This second analog voltmeter had a dual scale - both torque in foot-pounds and horse power. Below this meter was a two position switch that allowed the meter to be switched between reading out torque or horsepower. This switch was set up to determine what the voltage source was that fed the input of the variable resistance divider that measure the torque reaction. If the switch was placed in the horsepower position then it would feed the voltage generated from the RPM sensor (generator) which would result in the variable resistance divider performing the multiplication function to calculate the horsepower. If the switch was placed in the torque position then it fed a constant DC voltage to the input of the variable resistance divider. I was charged with the task of calibrating this instrumentation which resulted in the need to calibrate the various parts in a very specific sequence - the RPM meter was first calibrated by adjusting a scaling potentiometer for the RPM meter. Once the RPM meter was scaled the next stage was to calibrate the DC voltage for feeding the variable resistance divider for the torque measurement. This involved spinning the dynamometer to 5,252 RPM and measuring the output voltage from the RPM generator. This measured voltage was the voltage that the fixed DC power supply had to be adjusted to that fed the input to the variable resistance divider. The next step was to adjust a potentiometer for getting the torque meter to read correctly with this DC voltage applied and a fixed known weight on the torque reaction arm to simulate the effect of an applied torque. Once this was completed the entire instrumentation was calibrated - there was no actual calibration step for calibrating the horsepower reading as it had to be correct based on the underlying mathematics.

[@Dustii91]

Even to have spent 6 minutes to find out its meaningless, I still feel as though this video contributed to my education! Thank you 👌🏽

[@04silverado6.0]

This has to be the first video of yours that went straight over my head.

[@paulontheroad]

Back in a time before calculators I spent an afternoon at a car museum with an engineer who would do those calculations with a slide rule. It was all magic to me at the time and it wasn't until a couple of years later when I got to college that I figured out how he did it. Great explanation.

[@in3kro274]

Just one thing, we also talk about horsepower, which has the same value as the BHP (british horse power) and is roughly 830 watts or 0,83 kW.

[@smitajky]

As power and torque are not the same thing you can use ANY vertical scale for either and alter the point at which they cross. ONLY if you use a scale where 1 foot pound of torque has the same scale as 1 horsepower is your statement going to apply. And it does depend on your definition of an HP too.

[@paolocastellano2771]

I never thought of why they cross at 5252.... Great explanation!

[@tituslawoffice4778]

I've been reading car magazines since I was a kid and I finally understand force, power, and torque.

[@rattiofficial]

Now looking at a dyno sheet I can forever spot the correct units by looking at the shape of the curves. Thanks. :D

[@Iffy50]

I use the formula HP=T*n/5252 at work all the time. (T=ft*lbs, n=RPM). I'm sure I saw the derivation many years ago, but the 5252 rings a bell because it's commonly used. (33,000 doesn't really ring a bell) Good video!

[@pingshakl]

I knew it's pointless. And you explained it correctly and clearly. Well done.

[@User85306]

After that title I started very much doubting your competence…till 04:44😂😂

[@elecrticityelectronics8591]

1- What do you mean about RRM... Is it wheel or engine RPM. According to what you saying, it's wheel's one. 2- According to you, all engines power and torque curves cross at same value of RPM, 5252, which seems to be abnormal.

[@DaveMcLain]

They do all cross at 5252 engine rpm no matter what engine or rpm capability. At 5252rpm torque and HP are always the same.

[@eklhaft4531]

Fun fact: HP is how much power the horse can sustain over several hours. If he is towing a carriage he can output around 20 horse power when getting it to move.

[@mrid5850]

I only understand the most basic math. But when you explain it, it all makes sense. Though it is totally useless. Learning that something is usless can be very usefull.

[@771]

This has helped me understand math as a whole. Since it was actually interesting to me rather than cramming it in class, it naturally clicked. Great video!

[@robertjury6745]

I understood it once I used a farm tractor Dino on the power take off. The 1 foot beam and a load cell measured foot pounds of torque mulituplied by RPM divide by 5252 = horsepower produced.

[@juanc5149]

Because hp is simply a calculation of torque applied over time. And in this case the measurement of energy, Horsepower, adds up so that at 5252 rpms it matches the measurements of force ft-lbs. Crossover is at different If change the measurements. If you use newton meters the crossover happens at 7,121 rpms.

[@ronhollenbeck]

I sat down a couple of years ago and figured out where the 5252 came from. I always wondered how many car guys knew where it comes from. Thanks for sharing online.

[@rannug77]

These videos work better than any ASMR videos on KZbin! Really helps!

[@Crazystuffyousee]

Good video.....but I think its important to understand that even though HP and Torque are different units HP isnt real but merely the mathematical calculation of the work done over time. Saying an engine has "X" horsepower is actually pointless without knowing what Torque it produces. The automobile marketing industry has consumers taking the two variables for granted.