The Best Way To Compare Car Engines - BMEP


What Is Brake Mean Effective Pressure & Who Makes The Best Engine?
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One of the best ways to compare engines is BMEP - Brake Mean Effective Pressure. This is the average pressure applied to pistons during the power stroke that results in the measured torque output. In simple terms, it's a way of analyzing torque per liter of engines. Using BMEP, we can answer fascinating questions: How is Ford's 5.0L Mustang engine more impressive than Ferrari's 812 Superfast V12 (at its time the most powerful naturally aspirated engine in any road car ever)? What's embarrassing about Rolls-Royce's twin-turbo V12 engine? How much power can naturally aspirated engines make? Is it worth modifying naturally aspirated engines? BMEP answers all!
BMEP is fascinating! If you watch through to the end, I'm 99% sure your mind will be as blown as mine was researching for this video! Really cool stuff, like how Ford shows up Ferrari with the Mustang, how Rolls-Royce builds a head-scratcher of an engine, and if naturally aspirated engine mods are actually worth doing. Hope you enjoy!
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  • Engineering Explained
    Engineering Explained9 måneder siden

    *Warning!* A little derivation will be involved, but it will be worth it! BMEP is fascinating! If you watch through to the end, I'm 99% sure your mind will be as blown as mine was researching for this video! Really cool stuff, like how Ford shows up Ferrari with the Mustang, how Rolls-Royce builds a head-scratcher of an engine, and if naturally aspirated engine mods are actually worth doing. Hope you enjoy!

  • mornifle57


    4 dager siden

    Hey, nice video! But it seems it's not the specs of the Mustang GT but the Shelby GT350 instead

  • Mgoblagulkablong


    Måned siden

    2021 Mazda Skyactive X just broke the record, 240 Nm 1997 ccm

  • solidXxXtuna


    4 måneder siden

    @srinitaaigaura Taking an engine offered with either FI or NA and comparing the NA form to other NA motors like you did with the TFG is the only way to get apples to apples. FI motors usually run lower compression ratios by design so just subtracting the boost from an FI engine doesn't give a good number for comparisons except against other FI cars minus boost.

  • TrumanHW


    5 måneder siden

    Aren't we just comparing the atmospheric pressure to the engines pressure..? Also -- isn't the difference between the input fluid & output fluid temperatures directly indicative of the power it'd make..? Colder input ... greater change, greater power. Hotter output ... greater change, greater power. ...? Input and output are EQUAL ...? No power generated. No..?

  • Luke Chapman

    Luke Chapman

    6 måneder siden

    To be fair the RR hit that superb torque at barely above idle where the ferrari is screaming... its all in the map too.

  • Abg Bengkel
    Abg Bengkel2 dager siden

    Hello sir..can we simply find out the pressure by using pressure guage...

  • Skibum Wannabe
    Skibum Wannabe3 dager siden

    Not explosions, rapid burns. Unles your engine is pinking

  • Noctilent
    Noctilent9 dager siden

    EE: "...They'll walk away from you." I felt that

  • Bradley Howe
    Bradley Howe12 dager siden

    What impact does RPM have on this. For example, one of my engines calculates to 12.67, but peak torque occurred at 4200 RPM, and I was already making 600 ft. lbs at 2000 RPM, whereas the Ferrari you showed above I would gather was spinning considerably faster. Is there a way to compare these and take into account engine speed? sort of a work per speed calculation?

  • Craig Horner
    Craig Horner18 dager siden

    the modern supercar engine might not use cams to time the valves but may use pneumatic actuated valves. this allows the timing to be very precise so that the engine will be able to develop the maximum amount of torque over a larger rpm range than anything that ford produces and especialy gm which, last i knew, still used the same basic engine design that they have had since the 1950s which is a single cam shaft with pushrods actuating all the valves of the engine which does not allow for variable cam timing. so to your point, the only way to get that average pressure to be as high as possible is to implement variable valve timing, polished intake manifolds and exhaust ports, and an efficient combustion chamber and piston design that would efficiently use the detonation of the fuel/air mix

  • Gabe Shaw
    Gabe Shaw20 dager siden

    Bruh did this guy really just say distance?

  • Andrew T
    Andrew T24 dager siden

    Toyota/Lexus’s 2GR-FSE: 13.7 bar, quite impressive for a NA engine that was introduced 15 years ago.

  • fzerox3core
    fzerox3core29 dager siden

    I have a ct4-v and im calculating over 20 bar is this correct?

  • maoboyz
    maoboyzMåned siden

    Jason you should stop using time for multiple when time is involved in the equation.

  • Neil Sandage is Founding Fathers
    Neil Sandage is Founding FathersMåned siden

    2:39 ~ Force is Pressure * Area of piston head, yet an inflatable mattress pump and bike pump dramatic recoil power, if any resistance or torque to push against. Ultra Lean if Narrower Head.

  • 860 Syam Krishna.
    860 Syam Krishna.Måned siden

    Can you please tell me how to increase bmep?

  • lazy troy
    lazy troyMåned siden

    i found B38 engine on i8 is 10.7 bar

  • Ashutosh Verma
    Ashutosh VermaMåned siden

    6:40- They'll walk away from you 9:35- It breaks the scale, that I made up 😂😂 😂😂 Jason funny AF

  • Surf Board
    Surf BoardMåned siden

    So, then help me understand the new 2022 BRZ in terms of BMEP and HP potential for an N/A build. I'm not sure you included the math in the spread sheet at the end, so it's difficult to understand. If the BMEP of the new engine is 13.03759 ((4x3.14159x249)/(2.4*100)) then what is my max potential?

  • Flatzee1
    Flatzee1Måned siden

    I cant do the equation properly. My car has 430nm of torque with a 2.0L engine.

  • Mgoblagulkablong
    MgoblagulkablongMåned siden

    2021 Mazda Skyactive X just broke the record, 240 Nm 1997 ccm

  • Cale Benson
    Cale Benson2 måneder siden

    I did the math on my 2010 mazda cx-7 with an na 2.5L and the bmep is right around 8.1😂

  • StereoSoundAgent
    StereoSoundAgent2 måneder siden

    solid video as always! one super tiny thing,your equation 4π(718Nm)/6.4966*100 should actually be (4π(718Nm)/6.4966)/100 in order to equal 13.9 Bar. I just decided to play with your equations myself and noticed this small error.

  • Herbert von Sauerkraut unterhose
    Herbert von Sauerkraut unterhose2 måneder siden

    My first truck, a1975 model man had a N/A 15.5L V8 with 4 valves per cylinder only putting out 304 DIN horse power and 1050 Nm of torque.. it was a big engine.. D2858 MX engine as I recall.

  • Rick Yaeger
    Rick Yaeger2 måneder siden

    Thanks for your videos. A great balance of information and interest.

  • Aaditya Pratap Singh
    Aaditya Pratap Singh2 måneder siden

    I got confused for a bit. The whiteboard says "GT3 RS", while you used a video of a GT2 RS. The latter has a turbocharged flat-six, while the GT3 RS has a naturally aspirated version of the same. I couldn't understand the derivations at all; I used to hate them with a passion in physics classes.

  • Hr BeStalkinMe
    Hr BeStalkinMe2 måneder siden

    I compare on durability.

  • sw1sha442
    sw1sha4422 måneder siden

    BMEP isn't all that useful, sure it's related to other quantities, but BSFC rules for cruising and power density rules for going fast. Weigh those against MTBF and cost of ownership as suits.

  • 3xoticG4m3r
    3xoticG4m3r2 måneder siden

    Ok i am at 8 minutes, maybe this gets solved but my mercedes c220d has a bmep of 25.1 bar: (4*π*400nm)/(2liters*100)

  • 3xoticG4m3r


    2 måneder siden

    Ok he explained it, i should have thought about turbochargers :)

  • Humdan A
    Humdan A3 måneder siden

    This is beautiful

  • Antnee
    Antnee3 måneder siden

    "Spreadsheets Heck Yeah!" Made me laugh 😂

  • drewe burgess
    drewe burgess3 måneder siden

    It would be interesting to do a video of this using modern sports or super bikes, it's not unusual to see a 1000cc bike producing nearly 200hp.

  • G M
    G M3 måneder siden

    Er, wow.

  • G r a h a m
    G r a h a m3 måneder siden

    Flat plane crank is in all the top scoring engines. Ever wonder why a Ferrari V8 sounds different from a Chevy V8? It's all in the crank. To bad no one makes a flat plane crank for a sbc 305 sure wake up a few old dinosaurs.

  • best of the best
    best of the best3 måneder siden

    For me the Best engines Are the ones that get More hp per liter

  • Dávid Červeň
    Dávid Červeň3 måneder siden

    I calculated a MEP of a Dodge Viper ACR ... does it really have a MEP of 9,5bar ??

  • alex luke
    alex luke3 måneder siden

    It would be interesting to see the T.50 engine breaking that scale

  • atzeti
    atzeti3 måneder siden

    You are showing 14,2 bar for the Mustang GT. That is not correct I think. The GT has 529 Nm and 5038 ccm what makes 13,19 bar. The Shelby GT 350 has 582 Nm and 5163 ccm what makes 14,17 bar.

  • atzeti


    3 måneder siden

    Could the Otto Particle Filter, which is on the Mustang in Europe, the reason for the difference?

  • atzeti


    3 måneder siden

    Just found out the US numbers are 420 lb.-ft. which equals 569 Nm. That would make 14,19 bar. The EU number ist just 529 Nm. How is there such a big difference???

  • Malcolm X
    Malcolm X3 måneder siden

    Published compression ratios are based on swept volume to combustion chamber volume at TDC. This does not take valve timing into consideration. Engines with extreme valve duration and overlap need high static CRs to compensate for that.

  • Bill newlands
    Bill newlands3 måneder siden

    Once again brilliant lesson in Engineering! I liked the drag car engine, I have often wondered how they get so much grunt. Thank you

  • Nick
    Nick3 måneder siden

    "The lowest I could find, 2020 Mitsubishi Mirage" Is there anything the Mirage doesn't suck at??

  • dana cook
    dana cook3 måneder siden

    when I was in school studying aircraft engines we always did a horsepower per specific fuel consumption to compare engines. I think that would be interesting to do here.

  • Guillaume Joop
    Guillaume Joop3 måneder siden

    Just confirming what I already thought about the ideal engine for a project car : N/A, large displacement, low compression ratio, short stroke, strong block, preferably a flat-4 for that sweet balance. Sound like a subbie to me, does any of them fit in a na miata ?

  • Benz Ouyang
    Benz Ouyang3 måneder siden

    I know your video has a tongue-in-cheek component, but still…The Toyota XW50 Prius' 2ZR-FXE engine has a BMEP of 9.9 (Boo!). Yet, it has a thermal efficiency of about 40% (Yay!), thus proving that BMEP is merely just another measure of an engine, and not a particularly interesting one for most real-world use cases.

  • calgrizz52
    calgrizz524 måneder siden

    You make me like math again!

  • Michał Bocian
    Michał Bocian4 måneder siden

    2.0 TSI, 380NM, 300HP, BMEP: 23.8

  • Fabian
    Fabian4 måneder siden

    what about the 2.0 liter amg engine in the new A45 amg and cla45??

  • zach prieur
    zach prieur4 måneder siden

    Im curious, how much this chart of engines bmep would get rearranged if the same equation was done but with average torque and not peak values

  • JRE
    JRE4 måneder siden

    Take into account reliability more pressure = more stress

  • ieong nathan
    ieong nathan4 måneder siden

    Should have compared the bmw engine in Mclaren F1

  • Lance Lee
    Lance Lee4 måneder siden

    As an old Mech E major, this is my ASMR.

  • Wayne Cruz
    Wayne Cruz4 måneder siden

    When I was a kid I thought rpm was the tires

  • Kuromurasaki Zero
    Kuromurasaki Zero4 måneder siden

    (4*pi*Nm)/(L*100) ... Renesis rotary engine - 216Nm, 1308cc; 20.8 BMEP? edit: changed pie to pi; must be hungry :)

  • Michael Free
    Michael Free4 måneder siden

    Hrmm. Top fuel BMEP of 166 bar, because I'm a backwards American let's call that roughly 2400 PSI. Since a fueler has a nominal 4.1875" bore, that means those head studs are holding down a force of 33,053 pounds, average, during firing events. Well, that explains the explosions when things go wrong.....

  • Christian Loper
    Christian Loper4 måneder siden

    My 2007 Civic's BMEP is 8.38 lol.

  • xwaltranx
    xwaltranx4 måneder siden

    Minimum fps is not important give us the 99 percentile frame times oh this is not pc content oops

  • Albert Santoso
    Albert Santoso4 måneder siden

    This could've turned many car guys/girls into math in HS and colleges. :)

  • qwkutiub
    qwkutiub4 måneder siden

    10:18 But wait, don't long stroke (long crankshaft throw) engines usually make more torque? If I have understood it correctly, the crankshaft throw is the r the goes away in eq. 8, so BMEP doesn't take it into account. If a longer throw helps an engine make more torque, then that should be reflected in its BMEP… :S

  • Mike Furlong
    Mike Furlong4 måneder siden

    I think we'd all love a follow-on video of a discussion of how various design elements affect BMEP. You mentioned CR and VE (but only in regard to tuned runner lengths). Perhaps you could discuss in more detail some of the features that allow the better engines to achieve higher BMEP, and which factors are "baked in" when the head / block is cast, and which can be affected by aftermarket tuning?

  • RS2Russ
    RS2Russ5 måneder siden

    Surely this implies diesel engines are the best engines? If that isn't a flaw in your methodology, I don't know what is!

  • said alamry
    said alamry5 måneder siden

    Am i crazy or is the p1 according to his formula a 29 bar bmep??

  • Pedro Domingues
    Pedro Domingues5 måneder siden

    Come back to this with Gordon Murray T50

  • Joe Dasilva
    Joe Dasilva5 måneder siden 3.0L v6 at 204 hp has a 17.0 BMEP?

  • Be Bestest
    Be Bestest5 måneder siden

    Big Maths

  • Andy Sen
    Andy Sen5 måneder siden

    Wow...I am shocked ~ I gotta go lie down. Amazing analysis ~ I will never look at engines the same way again! Please help on how the 2021 Mustang Mach 1 5.0 would compare to the Dodge Challenger 392 & Chevy Camaro 2SS 6.2, naturally aspirated engines, as I’m torn between the 3 in buying a new car. Your help would be much appreciated, Sir.🙏🏽

  • Shock Diamond
    Shock Diamond5 måneder siden

    366,895 views and I'm the only one who noticed _the toy car you used on your forearm is the The Fast and the Furious Mitsubishi Eclipse_ ?

  • haj mamad
    haj mamad5 måneder siden

    mazda quadrotor :29.33 bar

  • Fez A
    Fez A5 måneder siden

    Brilliant explanation. Thank you

  • Robert B
    Robert B5 måneder siden

    I usually watch your videos when they are available. I just saw this video on my list. Great video, very informative. I have a modified push rod 5 litre fox Mustang that makes the same amount of tq as the new Gt. It's nice to know I have roughly the same efficiency as the new engine. Keep up the great content.

  • Apurv Jadhav
    Apurv Jadhav5 måneder siden

    I think time covered by piston to travel stroke should be taken as RPS/4. As piston travel 1/2 the revolution (180° out of 360°) for power stroke.

  • Joe schmo
    Joe schmo5 måneder siden

    my 1978 olds, 4.3l

  • Mehak jot Dhillon
    Mehak jot Dhillon5 måneder siden

    Make a video on how to increase BMEP without adding turbo..Waiting for your reply.

  • Alastair Stedman
    Alastair Stedman5 måneder siden

    Does calculation. Works out his Honda Jazz 1.5VTEC has a BEMP of about 12 bar. Not bad.

  • Derek Someda
    Derek Someda5 måneder siden

    rx7-8 2 stroke can double hp@ tq per MEP or boost level brilliant

  • 2605155
    26051555 måneder siden

    So what I learned from that is: Some speed shop needs to hop up a Rolls Royce. Let Alpina have a go at it.

  • Elias Håkansson
    Elias Håkansson5 måneder siden

    In theory Koenigsegg should be able to optimize the volumetric efficiency in the Gemera by optimizing the manifold airflow with Freevalve?

  • Justin Bigelow
    Justin Bigelow5 måneder siden

    I have to say first how much I enjoy your videos. Your ability to use equations to describe your point is impressive. I was fascinated as well when I learned that engineers were able to get over 100% efficiency out of a naturally aspirated engine. One thing I noticed you neglected to mention in that is how important valve timing, overlap, and size play a roll in both air velocity and pressure. They use the exhaust valves scavenging effect to draw fresh air in like a vacuum during the overlap to maintain air speed. Also why the ratio of the intake valve to exhaust valve size can be so critical. Again hats off to you for super fun content. Thank you.

  • Dustin Hollenkamp
    Dustin Hollenkamp5 måneder siden

    Could you use a pump of some kind to increase air pressure in the cylinder?

  • Muhammed Anees C.A
    Muhammed Anees C.A5 måneder siden

    ഒന്നും മനസ്സിലായില്ല... എന്നാലും ഫുൾ കണ്ടു....

  • slowboat
    slowboat5 måneder siden

    wish you wouldn't simplify things so much, I might loose my job LOL In relation to turbo charged diesel SUV vehicles: how do aftermarket tuners get 50 or 100% more torque and power from an engine and (claim to) have better fuel economy? if this was a viable tune why would the manufacturer sell a gutless inefficient engine when the first thing everybody looks at is economy, torque and hp?

  • Bevin Alexander
    Bevin Alexander5 måneder siden

    My mom thought this was on zoom in a math class

  • agt155
    agt1555 måneder siden

    The Caterham R500evo had a N/A Rover K series engine (2.0l, 190lb/ft) giving a BMEP of 16.2 bar.

  • clint h
    clint h5 måneder siden

    So a Alfa Romeo 4c makes like 147.5 worth of torque per litre 😳 what!!??

  • eriknephron gfr
    eriknephron gfr5 måneder siden

    John Cadogan

  • Matt H
    Matt H5 måneder siden

    Cliff notes: More displacement and high compression ratio produces more torque. Duh

  • Justin Partlow
    Justin Partlow5 måneder siden

    Need some motorcycle representation. MotoGP engine vs the F1.

  • Space Wave
    Space Wave5 måneder siden

    So the Civic R is 21.4? That can't be right.

  • Eric Mueser
    Eric Mueser5 måneder siden

    So we divided the Koenigsegg by it's amount of boost, but we don't divide the 458's engine by it's intake manifold tuned pressure. So I'm not sure the Ferrari's 15.1 is fair, since it's still forcing more air into the cylinders than just 1 atmosphere.

  • Romo VA
    Romo VA5 måneder siden

    The BMEP isn't very good for LSX, General Motors engines..... but the engine are small, powerful and somewhat efficient. I guess it is just one way of many to compare the engines.

  • Pnner1
    Pnner16 måneder siden

    Didn't watch but only non-wimp-things that matter are either displacement, power, revs, torque or boost.

  • Andrew Acton
    Andrew Acton6 måneder siden

    Thank you for the two stroke shout out

  • F165
    F1656 måneder siden

    This guy is good with a white board. I can’t believe he doesn’t know why those engines are making so torque. The reason those engines are making so much torque is because they have very high lift and duration cams.

  • F165
    F1656 måneder siden

    I didn’t know the Mustang GT had more torque per cuin than the 812. I knew it had more torque per cuin than the Corvette.

  • Ed Cew
    Ed Cew6 måneder siden

    It would also seem that exhaust valve timing could be a factor -- open the valve too soon and lose some pressure at the bottom of the stroke, granted, where the crank angles make piston pressure less effective. But you also don't want to expend torque pushing the exhaust gases out. Similarly for a tuned exhaust helping get the gas out of the cylinder.

  • Dan Cusin
    Dan Cusin6 måneder siden

    Love your videos keep it up

    JOSE DOMINGUEZ6 måneder siden

    You are outstanding 👍👍👍👍

  • Andy Harman
    Andy Harman6 måneder siden

    The highest naturally aspirated BMEP I have heard of is 240 psi (16.3 bar) on a 16:1 compression, methanol fueled sprint car engine.

  • Camillo Andrés Hurtado Acero
    Camillo Andrés Hurtado Acero6 måneder siden

    For curiosity, how can RR ENGINES, get pick torque at 1500RPM aprox. and been called Embarrassing?

  • ReedKoch 41
    ReedKoch 416 måneder siden

    Jason must have paid attention in algebra 👀👀 very video takes me a few days to understand 🥺

  • Jas B.
    Jas B.6 måneder siden

    Yes, and now for the diesel engines???

  • Jax Chan
    Jax Chan6 måneder siden

    My 2019 Volvo S60 is 34.9 Bar way better than all the vehicles that you listed

  • Linus Fondin
    Linus Fondin6 måneder siden

    I might have done something wrong, but according to my calculations a Lotus Elise cup 250 (my dream car) has a BMEP of 17,5. It has naturally aspirated engine.

  • Linus Fondin

    Linus Fondin

    6 måneder siden

    Pi•4(250Nm)/1,798L•100=17,4727066384 Or what I did on my phones calculator: Pi•4(250Nm)/1,798L = 1 747,270663843 1 747,270663843/100 =17, 47....Bar

  • Leecifer Voorhees
    Leecifer Voorhees6 måneder siden

    It would be interesting to know how the bmep relates to the gross volume of the engines you discussed in power to weight ratio.

  • Leslie Tolman
    Leslie Tolman6 måneder siden

    Oh boy. I've got soooooooo much to learn lol. On another note tho, ready to get married yet, Jason??? I'm only half joking.... I could listen to you talk all day.