The Best Way To Compare Car Engines - BMEP
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- čas přidán 14. 04. 2020
- 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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*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!
Remind me why there is no correction factor for boosted/ at altitude engines? get total apples to apples comparison
high regards From Bulgaria, great content every time,you are my engine mentor
Many thanks Jason. you explained it better than my high school teacher, I finally understood that after 40 years.
@@rat_king- Unless you know the volumetric efficiency for each, there's no way to know how much air each is taking in. An engine with 15 PSI of boost has double the air of naturally aspirated engine, but if that naturally aspirated engine is operating at 120% volumetric efficiency, the engine with 15 PSI of boost actually only has 66% more air, not 100% more.
Neat.
Jason is a BMEP.
Big Math Equation Person
@@Mexxx65 ikr..
342.
Elementary school level of math and physics. I mean I love it but it's as simple as it gets!
@@Mexxx65 its a good comment. Big math did occur.
GFNoivern Its called Engineer, Greetings colleague Jason , Electrical and Mechanical engineer here👊
Jason lowkey flexing that his brand new miata is as cool as the LFA
9:20 he couldn't contain his smile
"It's basically an LFA"
- me at the next cars & coffee
@@EngineeringExplained Is this the new "My s2000 is basically a Ferarri"? Now i see why you bought it.
@@Mexxx65 to be honest though. It actually is mine and has been for a while. When I am finished with college and have a real job, that is the car I am buying.
@@Mexxx65 Gotta shove them facts boy!
Fun fact: The Cosworth DFV has a BMEP of 13.9. Quite impressive for an engine made back in 1967.
Ah yes, the Universal race engine of the 70s
"...they'll walk away from you." - You said that with conviction. You must have experience!
Doesn't even phase him.
I like it.
Me: "is this going to be a normal video?"
Video starts with Jason in front of a wall of math
Me: "ahh, just like I remember."
I feel you.
Shitty how much physics have to work for your *brrrap*
The physics interests me MORE than the brap
" A WALL OF MATH " LMFAO.
@@NoWr2Run WALL OF DEATH🤣
GAY AF
"...IT BREAKS THE SCALE (that I made up)..."
I almost spat my coffee when he said that lol
That's just CRAZY!
@@EngineeringExplained I chuckled because it's just so... you!
Bruizey It really is very characteristic of Jason, particularly the delivery!
At 120% of natural air pressure you’re looking at nearly 3 lbs of boost with an intake, this is very impressive!
"it breaks the scale -- that i made up" sums up my life
You meant to say it sums up your eating habits?
The Rolls-Royce engine is most likely optimized for smooth power delivery (flat torque curve) and quiet operation.
Yeah! That sounds logical! Given the fact that you are driven in a Rolls not driving it.
Exactly. It’s meant for effortless and unnoticeable acceleration. It’s not meant to be super powerful like a 458. It’s meant to waft down the road without bothering its passengers
good job, you watched the part of the video where he explained exactly that.
Great that's all I came here to see debunked. Thx
Turbochargers are pretty effective as an additional muffler. Keeps engine noise down when combined with a good exhaust system.
"only compare similar vehicles!"
> compares the mitsubishi mirage with the ferrari 458
haha very cool video
😅
I actually used a Toyota Echo for pulling a tree once 😅 it worked
@@m.morininvestor9920 prithee allow me to bethink about thy actions...
its not smart to pull a tree with a car... also "tree" could mean anything.
Use
Use d
If I was back in high school with him as my teacher making these equations relevant to my interests then I would of been an A+ student
That's your fault that you didn't find the beauty in math/physics, not your teachers lol. You were, at least then, just Naive. Anything you could imagine, can be explained by math/physics/chemistry. Nothing has been created by accident. It's a beautiful thing when you start to realize how things work isn't it!
@@j.m.7907 Teachers rarely do anything to incentivize such discovery with math though. Math is extraordinarily dry for most without some practical applications to tie it to.
You're right about what you said. But the biggest issue is actually our education system. If they want most if not all children to succeed in school, then they need to be teaching us in ways that will cater to our interests and strengths. You can't have an education system where only some people will succeed and others won't, that's a flawed system. Unfortunately, that is the reality and it's sad that we pay taxes to a flawed education system.
JOEY M You’d be an awful teacher with that attitude. Literally every science educator out there would disagree with you.
Joel West I took a physics 101 type class and the professor made it fun by showing practical applications that everyone could relate to. Way better than any science class I had in high school. I actually looked forward to that class.
Ha, I haven’t seen BMEP calculations since my ICE course in Mech Engineering 🤓🤓. Wünderbar
15:30 "Let's say this is a 2.0L engine we're modifying". Gee, I wonder why? ;)
I am too lazy to do it and maybe I lack some of the variables but I would really like to know the BMEP of the m133 2l 4zyl Engine in my A45 with 381Hp would have. And more so the new m139 with 2l in the current A45 at 420HP..
Someone: hey my Ferrari V8 is amazing
Jason: (takes out a whiteboard)
nice. I'd sit and listen.
Actually, the V8 458 IS amazing.. It's the V12 that isn't (as much)
@@davidstepan8490 The Ferrari V12 is one of the most amazing engines out there right now. Who wants to live in a world where every car is a small turbo 4 cyl with 2000ccm or even worse: only electric cars.
Be glad for the variety.
@@nik7bkh965 who would want to live in a world with no air microparticle pollution
@@MaxxerG I know right, I'll keep my freedom to get lung cancer and other respiratory problems, and brain damaged kids thank you very much
I would really be interested in a video about BMEP calculations for rotary engines. I know they dont have many "similar engines" to compare with, but it interests me nontheless. Great video as always :)
I found a formula sometime ago that used the maximum torque the engine made in lb/ft, multiplied by 2473 then divided by the cubic capacity. e.g. 425(lbs/ft) x 2473 / 5665(c.c.) = 185psi [~200psi being about the upper limit for N/A engines]
Excellent
The constant 2473, will come about as the result of multiplying an assumed rpm(that of an average rpm for peak torque?)
by the necessary unit conversion constants.
Thus the formula will estimate on the high side for engines that make peak torque at lower than the assumed rpm. And estimate lower thsn true BMEPs for engines that make peak torque at higher than average RPM.
To be fair to Rolls, they want that engine to be as quiet as possible, and to last at least 10 years without needing an overhaul, while the Ferrari is likely to not make the distance, and in general will not be a daily use car like the Rolls. Thus run the engine in a lower stress region, but have the turbo small to maker it accelerate fast off the mark, giving the impression desired of "effortless power", the exact opposite of the Ferrari, which is meant to be heard.
the engine is also designed to have a very flat power curve over the rev range, to make it feel smoother
You're absolutely right. 👌
@@tommihommi1 Also true. 👌
Great point on reliability. The topfuel dragster engine can only go 1/4 mile between rebuilds to achieve its number.
@Nabil Sabli "Thats how impressive rolls engine is in terms of refinement" You mean "BMW engine", right? :)
8:58 "... extraordinarily expensive and super fast." LOL I love how you are working the geeky sense of humor into the videos. Thanks for another great video.
The joy of learning how it all works. I love "Engineering" when it is "Explained". Thanks Jason for a great video as usual.
I'm going to be so cool at parties. Too bad we're in quarantine and my dogs don't understand anything other than if they sit long enough they get peanut butter.
Jacob Wagner what the hell does this comment have to do with this video? Go like farming elsewhere
My BMEP is bigger than yours
I bet they get the peanutbutter. 😉😉😉😉
The kitty gets the milkshake and the bunny gets the pan...cake!
@D.O.A. 🤣
"Spreadsheets Heck Yeah!"
take my thumbs up EE :p
This is one of your best physics lessons in my view. I’m an earth science teacher who enjoys watching other great teachers teach. I’ve also enjoyed working on, maintaining and analyzing engines, airplanes, cars and motorcycles since I was a child, the offspring of an engineering wizard. So I like the topics you discuss. You have a great teaching style. I hope you keep this kind of thing up for years to come. We need more teachers like you who can inspire as well as enlighten!
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.
Basically:
BMEP (bars) * 8 = Torque from 1 liter displacemant [4 stroke engine]
BMEP (bars) * 16 = Torque from 1 liter displacemant [2 stroke engine]
for US:
BMEP (psi) * 0.544 / 61 = Torque from 1 cu inch displacemant [4 stroke engine]
POWER:
Torque (NM) * RPM * 0.104 / 735 = Power (PS)
Torque (lb-ft) * RPM * 0.142 / 745 = Power (HP)
Thank you.
Was wondering. Thank you so much
Jason basically speaking gibberish the entire time:
Me: Yes, I completely understand
lmao, I don't even have to watch the video to figure out that I'm not gonna understand anything. But I watch it anyways cause it makes me feel like I know about cars.
As my professor used to say "IT'S ALL ABOUT THE UNITS"
Problem is I understand, I really do, but chugging down all those informations in 16 minutes is hard so I forget everything a the end. His whiteboards are between 1 and 2 hours of physics class
if this is gibberish to you, you might need to go back to highschool
ME RIGHT NOW
Engineering Explained... is really the perfect name for this channel. I've learned so MUCH cool stuff on here! Thanks Jason for continuing to come up with fantastic video content, and making it INTERESTING. Stay safe amigo!
I’m glad there’s another smart person out there thinking in engineering terms. Years ago, when I talked like this in my engine building class I got that “deer in the headlight” look from the instructor. Thanks for a great video. Now onto compression ratio, quench area and L/D intake valve calculations. Yes!
Can you make an online university just for car stuff like this. Right now with isolation and everything. I would be the first student. Great vid as always ! Up the Mazda with the 12.6 !!
Here you go! czcams.com/users/engineeringexplained
Bosch Automotive Handbook. You're welcome
@@EngineeringExplained Speaking of the Mazda, I'm surprised you didn't find the BMEP of the 2019 and later models. The tuning has been quite significantly revamped, or so I've heard. The power figures match that statement, too, with a pretty significant increase for such a small displacement. And yeah, I know the 2016 is the model you own, but come on, that thing basically copy pasta'd the Mazda 3 engine.
Edit: just searched it up, and yeah, the 2019 model saw an increase in almost 30hp which is like 20%, insane!
@@EngineeringExplained iiiii see what you did there!
@@olegkolesnikov7155 It's 12.9
"But think of how much more interesting people will find you at parties when you say words like 'Brake Mean Effective Pressure' instead of 'torque'... they'll walk away from you"
You mean "Keep their social distance".
Also... how are you having parties?
Most people will likely walk away when you say 'torque' anyways 😉
It is nice to watch a CZcams video that does not bore me with incompetence. Thank you for all the work you put into developing your videos.
Love the way you break it all down in you videos, informative to say the least. Keep it going! 👍🏻
If my math teacher in highschool used cars as a way to teach equations, I would have passed every class with an A+.
@B
(Estimated Seeds per watermelon * 10) -(estimated seeds per watermelon * 4) ≈ number of seeds
@B
I can't figure it out.
Is there a way to write an expression for that?
Ahh the old trick question, where knowing math is irrelevant but being good at English is.
My answer 0 I only eat seedless water 🍉
And that's why I did get straight A's in math - not because the teacher used automotive as the example, but I turned every example into an automotive, railroad, or machinery example!! Geometry and math were fun and I could understand the formulas in detail!!
He's literally the only person on CZcams who is capable of proving an MX-5 is just as good as an LFA.
yeah because an mx5 does 0-60 in 3.6s huh. LOL
Just as good in one specific metric that nobody ever heard of and means little in the real world, yeah :-D
Proving? i think you mean pretending
Its pretty much self evident, but the maths help ;-)
@@soundseeker63 when you say 'no one's ever heard of' you mean apart from all those mechanical engineers who use this daily?
Best...by far... content on the show!
To who can understand...altough it was laid down in a very comprehensive layout
Praise the excellent good work.
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.
Love cars, hate math - Jason is like my paradox emulsifier
Think of it like this, who do you want to teach you math, an old college teacher that doesn't care about real world scenarios, or this guy, comparing everything to car engines? This guy wins hands down. But then again, I don't hate math that much.
Karam J: Amen - if I’d had a teacher like him back in the day, maybe I wouldn’t hate math. (Of course that would had been before he was born) - I’m thankful for guys like him.
Big Mo - Paradox emulsifier? Now that's a great term! I'm going to use it at parties! That, and BMEP. Cheers!
@@BiggMo Nothing is stopping you from rediscovering the wonders of maths now.
I think these videos are very useful, especially for us mech engineering and automotive students, but you make it easy to understand even for other people. Keep doing this good work
This was seriously one the most fascinating videos you’ve done to date. Freakin’ awesome.
6:40- They'll walk away from you
9:35- It breaks the scale, that I made up 😂😂 😂😂 Jason funny AF
Perfect timing ! Just today I was looking for this info because found out bmep are always there on every engine spec sheet. Now I know, thank you !
Thanks for taking me back 20 years to my IC Engines class!
I think some people refuse to believe that for a daily driven car, top end power isn't as important as how the power builds up and how the car handles. Too many people think that they drive at redline 100% of the time and forget about things like torque and power to weight ratio.
yours videos are always great, but man this is just amazing!!
Oooooh, more tools for my social distancing toolbox
Great video! Two things come to mind:
1. The power stroke does not end at bottom dead center, it ends when the exhaust valve opens. This typically happens at 120-125 degrees after the piston reaches top dead center, so for the 55-60 degrees remaining after the valve opens, the cylinder pressure is effectively zero. I guess that BMEP means the average pressure over the 180 degrees from top to bottom, despite there being no pressure for those 55-60 degrees?
2. Two engines with the same BMEP, the same displacement, and the same RPM can have quite different mid range torque and thus power. If one of them has a very long connecting rod and the other a short connecting rod, the long rod engine's piston will "dwell" for a longer period near the top of the cylinder while combustion is taking place, thus developing far more pressure than the short rod engine, and it will have way more power in the middle of the RPM band. Why? Draw this out on a piece of paper and you will see why. Draw a crankshaft throw and a connecting rod/piston that is long and another one that has the same stroke but a rod half as long. Imaginarily move the long rod's crankshaft 15 degrees or so and see how far down the piston moves. Now, do the same thing with the short rod drawing- You will see with the short rod the piston moves FAR MORE than with the long rod. Since the exhaust valve opens typically while the mixture is still burning, the dwell period of the long rod design allows more of the charge to be burned before this happens which produces the same BMEP but with more actual torque and power for the long rod design.
Jason, you ought to do a video about this effect. Volkswagen used very long rods in the VR6 engine just for this reason.
Ha! Smokey Yunik said "stuff in the longest damn rod you can"!
Agreed - rod/stroke ratio is pretty dang cool, and I'm sure there is a lot more I could learn about it.
Sorry, item #2 is not true. By definition, if two engines have the same BMEP , same displacement, and the same RPM, then they will produce exactly the same power. This is by definition and is not subjected to any variation in other engine parameters.
Now, WRT long connecting rod, you will have higher dwell time at TDC, and you will have higher heat loss to the engine's combustion chamber at lower rpm, when there is already plenty of time for the fuel to combust, higher propensity for detonation that you may have to reduce compression ratio, thus reducing top-end power and torque...so low-end torque will suffer, in exchange for may be higher top-end power when there will be more time for combustion at top-end RPM, but, you must reduce compression ratio, which will affect top-end power. Furthermore, longer connecting rod will make your engine more bulky, heavier, and higher reciprocating mass due to the higher weight of the con rod, which will require beefier bearings and pins...that may affect top-end RPM...engineering is the art of making compromises.
@@kennethalbert4653 That's not right. Prostrock will run a shorter rod than optimum so they can use a lower deck height and straighten the inlet port to the manifold. Basically you are relying in atm pressure to fill the cyl so it has priority, ie, a higher magnitude of importance, than small effects like rod length. In 2007 a 500cu Prostock was making about 1500hp@10,750, so at 3hp/cu NA they must be doing something right. lol.
BMEP is an average, ie, more initial and less latter evens out.
Port velocity has more of an effect in making torque then rod length. With a 2-valve engine we make max TQ when inlet port is designed to run at port velocity of 500-550ft/sec. NA engines are limited to a airspeed of 0.6mach(700ft/sec) before they go into sonic choke and stop producing power. If you want to see the influence of ports look at the LS1. It has a cam with an operation range of 3500rpm, but the engine will rev to double that because the port hits 700ft/sec at 7500rpm. The myth that a long stroke engine makes more torque because of the stroke is wrong. It makes more TQ down low because it has a small bore that only fits small valves and small ports, and this means the port hits it's velocity limit at a low rpm.
Thanks for your videos.
A great balance of information and interest.
That was really interesting, thanks for the video! The beginning reminded me of a physics class with the rearranging of the equations, it was great! Your videos are very informative and thorough, also I like the occasional editing and humor sprinkled in!
LOL this just boils down to you trying to cost justify putting a supercharger on the new Miata :p
Hi, Jason. You forgot to mention your BMEP of your previous sport(ier) car. The F20c from the HONDA S2000 has a BMEP=13.1. And that's on a 20+ year old design!
Take that, Miata!
Too bad it weighs an extra 500 lbs..
My Miata develops usable torque over the driving and racing range. I can start smoothly in third gear and race with the standard gearbox
Thanks for making videos. 👍Nobody else gets into the nitty gritty of gear head stuff like you do!!! Excellent work too, btw.
Can I get the spreadsheet you used to calculate every car's BMEP? Asking for a friend.
@Sub Scriptions huh
Send out the spreadsheet so we can calc our BMEP!! Great video!
It's torque/displacement with a unit conversion to make it a pressure unit. You can write a long looking equation to convert to work then to the pressure it would take for that volume per rotation which might seem easy in metric because it's a very base 10 system. However metric also make distinctions between force, mass, and weight and newton's take earths acceleration of gravity into account and the rotational nature of torque measurement means a pi is involved. Imperial units aren't any better as the unit for torque and work are sometimes expressed the same way and there are coefficients on practically every unit conversion. To avoid making errors I'll just write down some conversion factors below. Maybe that doesn't break it down but for comparison purposes between engines you can get an idea. Normally aspirated engines can be compared easily and it says a lot about how well they are tuned. Boosted engines have a bigger challenge with heat management and might also make a different decision about the engines ve vs the boost used and other things. You can make dozens of comparisons between the same 2 engines normalizing for different factors but how you weight them in your mind as important is somewhat arbitrary.
For nm/l to bar it should be nm torque/litter displacement * 0.12566 = bar bmep
Bar to kpa is bar * 100 = kpa to express it in kpa
Lb-ft/In³ (foot pound per cubic inch) to psi bmep is lb-ft torque ÷ cubic inches * 148 = psi
Psi to bar is psi * 0.0689
Love the videos, Jason. The math is way above me, but I like to pretend I understand everything you’re saying 😂. It makes me feel smarter
One of the reasons i like his videos, he actually explains the math pretty well, so that anyone could do it pretty much.
@@merlinevseichik9479 that's the definition of a good teacher!
you took the words right out of my mouth that's also why I watch BigCliveDotCom lol
This might be my favorite EE video! Great work!
Amazing, as usual. One of your best explanations.
please include motorcycle engines in your videos, they have impressive power for their displacement (200 HP per Liter is not uncommon for street legal bikes). For example the 2019 Suzuki GSX-R1000R has a BMEP of 14.83
my 1998 r1 have BMPE of 13.8230076758
My 97 Honda cbr 600 f3 with 66 nm has 13,85 and my 84 gpz 900 r with 85 nm has 11,65. Engine efficiency and design improved a lot between 1984 and 1997! In motorcycles you also see the same engines being tuned for torque in road and touring versions and hp in race versions.
My 2015 bmw f800gt BMEP=13.5, and can get around 60mpg. Well done BMW.
I was wondering about bikes, thanks
Tuning your car up to double the horsepower it can make naturally
That's why he named the spreadsheet Heck Yeah!!!
👍👍👍👍👍☺
I'm student in internal combustion engine your videos are great to learn my class in another languages TY
wow that chart is actually very cool for seeing what upgrades might do - awesome video
This was a really good video chocked full of interesting information and presented very understandably. Just one question, though: For distance you used the stroke, or the distance the piston travels in one half a revolution during the power stroke. For the time, you used the revolutions per second divided by 2 since the power comes only every other revolution. But, that’s the entire revolution, and the power stroke is only half a revolution, so shouldn’t you divide by 2 again, or rev/sec/4, to get the actual time the piston takes to travel the power stroke? (And for a 2-stroke engine, you would divide by 2. ) That would make MEP = 8 * Torque * RPS / Vd, or twice what was presented.
No.
That actually makes sense. Should be divided by 4 for a 4 stroke and by 2 for a 2 stroke.
I was playing this video in full screen and my siblings thought this was an algebra lecture........
Wow dude, everything single video you release is an eye opener.
So I saw the notification for this video while procrastinating on my Physics homework. Somehow you explained my physics homework better than my teacher could, and made it enjoyable too. Your videos are awesome, keep up the great content!!
Well done! I learned a lot! Now please explain diesel engine NVH apart from high pressure inside the combustion chamber. How some diesel engines are quieter than others.... AND high BHEP on low displacment engine does it have reliablity issues in the long run with that too much stress?
it's the rate at which pressure increases in the diesel that's the noisemaker, some alleviate that with 1 or 2 pre injections. Also a plastic sump to dampen noise coming out the bottom helps
Turbocharger converts part of the noise into the turbine rotation, which used to pressurize air intake (ofcourse, exhaust pressure and heat are converted too). Modern common rail injector squirts preinjection before main injection events to dampen vibration by harmonics. Also some engines actually have intake throttle, like my Chevy Captiva. While it mainly functions to maximize exhaust gas recirculation (EGR) system, it has side effect of noise reduction. Also modern heat resistant foam that is used under the engine cover and the engine hood also absorbs noise. Balance shaft is used as well to reduce vibration and therefore noise.
Ah haha... "more interesting at parties " ... like my future wife's reaction when I said "g-force." 😆
Awesome video dude! Looking forward for more videos like this in the future!
Brilliant video. Never has physics/mechanics/mathematics been so much fun and easy to understand! :)
There was me about to go “Woooahh my little Skoda is about 15 on that scale”... before I remembered it’s both Turbocharged and Supercharged 🤣
Love those twin charge engines! How is it going?
a twin charged Skoda? WTF.
*3.5 seconds of Google Fu later*
As yes, the wonderful VW 1.4 TSI.
Andy Fisher 2.3 seconds 0-gulag
Skoda felicia fun 1999= 10.6 bar
My 2001 Renault Clio 1.4 8v is only a 10.1 on the scale :(
Too bad this engine doesn't have a large aftermarket, or at least that I know of.
"Spreadsheets Heck Yeah!"
Made me laugh 😂
Respect to you Jason, you take the craziest concepts and explain them really well. I think maybe it’s a gift. I had a philosophy professor in college who had the same gift. Others could talk The Who semester and it made no sense. Not here. This video was SO interesting. I hope you consider applying to other types of engines. Cool.
I did this calculation on a 82 normally aspirated 2.8L Diesel Datsun 810 Maxima and compared it to my 09 BMW 335I 3.0L twin turbo. The difference was amazing. I thought that the 80hp old diesel engine was bulletproof because of the nature of being a diesel. But it had such a low BMEP that the engine was never under much stress.
Wondering where an S2000 would land, but I don’t wanna convert units lmao.
F20C: 13.1 bar, F22C1: 12.8 bar. Slight variation depending exactly which torque rating (used 153 and 162 lb-ft).
The s2000 would land in the puddle of oil the thing leaks and burns every 1k miles it runs. S2ks are great cars don't get me wrong but they are a bit heavy compared to the competition and they make power way to high in the rev range for a car that is daily driven on a regular basis. For a track car i'd buy an s2k in a heartbeat. For a daily driver i'll take a mx-5 rf so when the top isn't down I can keep the elements off of me and don't get the soft top buffeting like all the other soft top cars I've owned in the past and also when I take it easy commuting I get close to around 40mpg(38mpg was my highest and that was cruising down the highway at around 80mph).
Couldn't be bothered to work out the BMEP, but 76.5 lb/ft per liter puts it at somewhere between the Lexus LFA (73.7 lb/ft) and the Ferrari 812 (81.5 lb/ft). Not bad for an engine that was designed over 20 years ago!
@@soundseeker63 The Jag XK6 engine from the 1940's had over 70 lb/ft per litre.
Did the test for my 2014 Aprilia Tuono and it scores...
13.97! Higher than a Ferrari!
My Mercedes has nearly 20 so way better than you ;)
Very informative video, thank you!
Consistent PHD level content! Keep up the great work!
Wow, my 2003 V6 Mustang came out with 10.1. Although who knows maybe that isn't too bad for the time. Also Go Wolfpack!
Well my 1999 e36 323i makes 12.5🙈
Don't get me wrong I also like Mustangs :)
it's terrible, murican engines always sucked at volumetric efficiency
@@einstein1984 Pretty much. But they excelled in sheer volume!
That's because you got the V6!
Yeah, I've been noticing for years now that when it comes to motorcycles, despite wild variations of HP/litre between different models; there isn't that much variation in terms of torque/litre, with most of them being somewhere around 9-11 kgf.m/litre (keep in mind that virtually all bikes are naturally aspirated, AFAIK the only factory non-naturally aspirated motorcycle nowadays is the supercharged Kawasaki H2/H2R).
Jason, have you ever thought of comparing engines in the form of some integration of the power curve? Of course this would require some consideration; for instance if it were integrated in terms of rpm, you would probably have to choose an arbitrary range of rpm (say the top 3000rpm with greatest power), and this would not be ideal if you were to compare between engines with significant variations of the rev limit... So I
guess it could be in terms of a certain proportion of the rev range, for instance the top 50% of the rev limit (for a 6000rpm redline, this would mean the range of 3000 rpm with greatest power). I believe something like this would give you a more significant value to compare the ability to accelerate than simply peak power.
"Non-aspirated"? Never heard it called that before, doesn't really make sense to me either. Naturally aspirated or forced, the engine is supplied with air so would therefore be aspirated.
Still playing kill zone?
Thanks for the metric units regarding torque!
Awesome, very clearly explained.
10:55 So you're saying some naturally aspirated engine make boost?
Yes, a cylinder can fill more than "100%" if the air charge has momentum or a higher than atmospheric pressure wave forcing the charge in. This is why intake and exhaust runners are tuned.
RPS of the wheels is RPS of the engine divided by final drive ratio. Is that cancelled out by engine torque increasing by the same ratio at the wheels?
If you're referring to the power transferred from engine to wheel, then ideally no.
The power is just transmitted in a different way, from high RPS and low torque, to lower RPS and a much higher torque. The drive ratios just take the power supplied and make it easier to use in the real world, as engines like to rev much higher than wheels generally spin.
Brilliant explanation. Thank you
Very interesting as ever, thank you for all your videos.
After applying your formula I see that in my old BMW E46 325ci modified for track days (2494 displacement, 245 NM) the BMEP was at 12.34 stock and is at 13.30 after a chip tuning (264 NM)... not much, but I think that asking for more to a twenty year old, battle scarred engine would mean asking for trouble :)
P.S.: RR "low" BMEP for a turbo-powered engine means it is built to last (quite the opposite regardng the Ferrari engine). Also, increasing BMEP while maintaining the same engine original components (pistons, rods, cranckshafts) will ALWAYS result in shorter engine life simply because the original materials were not designed/manufactured to stand the additional stress.
This is the cost aspect of what he was saying, you are going to have to start moving to exotic materials and finer tolerances to get there.
Somehow feel like this needs a mentioning of a Honda K20 somewhere ;)
K20 makes about 100Nm/ liter if I'm not mistaken, with the Mugen FD2 Type-R being the most impressive at 110Nm/ liter and it maintained that number until peak power.
The BMEP thing just translates to Nm/liter, and the maximum potential for N/A motors is about 120Nm/ liter and 105-110Nm/ liter at peak power.
as a person who studied both advanced mathematics and graduated from an automotive college I appreciate the effort you came up with equation to calculate BMAP. Also why a Rolls Royce V12 Twin Turbo has a less effective BMAP is simply because it was never meant to be a race engine and was based on an old design meant more for comfort and low end torque.
However the 458 engine is a work of art. No surprise it won several award for best performance engine, highest HP per liter and also one of the highest revving engines on the market at the time. All of it being beaten by the Aston Valkyrie, but even so the 458 is still a mass produced sports car with all the warranties and probably doesn't need be rebuild every 50/100ks like most hypercars. Shows how much NA engines has evolved over time.
Well done Gerson. Looks like you can impact knowledge in simple terms
It would be interesting to see the value of some motorbike engine. Just for comparison.
Lucio Switch naturally aspirated:
BMW HP4 race: 15.1bar
Aprilia RSV4: 14.7bar
Kawasaki ZX10R: 14.5bar
CBR 1000rr: 14.3bar
BMW S1000rr: 14.2bar
Yamaha R1: 14.2bar
Ducati Panigale v4: 14.1bar
Supercharged:
Kawasaki H2R: 20.8bar (Boost: 1.4bar gauge) equivalent NA: 8.7bar
@@dernachtmannkommt Lets not forget the Brutale 1000rr 14.6 its a lot more comfortable to ride than superbikes ;) well until you going over 180 then you really miss having a fairing.
Usually lower but much higher rpms
Thanks@@dernachtmannkommt, so up towards the top end of the scale. But able to rev much higher than even high performance larger capacity car engines
@@AanjE I think you will miss the fairing way before 180 mph more like 100 mph
I don't think rolls is embarrassed about their engines...
Maybe they should be, but perhaps rich folk are impressed by throwing displacement or boost at engines instead of good engineering. As long as they sell big comfy cars I guess.
@@CompTechs for the rich folks,, bigger=better, more expensive etc..
@@CompTechs There's plenty of great engineering in that engine.
You can make an engine with massive BMEP by simply lowering the hell out of compression ratio, fitting a massive turbo and intercooler and cranking up the boost until just before it blows up. Doesn't make it a particularly impressive feat of engineering.
When the metric you're using to measure the quality of an engine gives you results that say an MX-5 is as good as an LFA that's a pretty big giveaway that that metric by itself isn't particularly useful or relevant.
@@CompTechs damn, people like you know nothing about cars... Rolls royce couldn't care less about a performance Stat such as BMEP, since their cars have a completely different purpose.
The engine needs to be silent, robust and definetely not high performing (good acceleration is not important in such car). The rolls royce is perfect in that case so stop mixing up stuff you know nothing about.
It's like saying "F1 cars are slow because they have low torque". You guys Completely missed the point.
I love these videos, helps me massively with my degree!
Great vid!!!! Excellent detail on bmep.
As a mechanical engineer, this is Porn🤤
Switched my major right from M.E. right before thermodynamics class... however this is still porn 💀💀💀🔥🔥🔥
My mom thought this was on zoom in a math class
Thank you, very informative, as always!
Super cool vídeo man. 👌🏼👌🏼💪🏽
I'm sceptic about all of this, in a constructive way, its nonsense.
how do you cancel out the RPS at step 9? the crankshaft and the wheels do not spin at the same ratio, at least you must've explained the particular case of using the 1:1 gear ratio of the gearbox.
Then you are making another big mistake, that is to take the torque at the crankshaft, because in step 7 you cancelled out the radius, and if you assume they are the same, you are using the torque at the wheels. Otherwise you'll be taking the crank radius equal to the wheel radius.
Cool video anyway, keep it up
Power is made by the engine not anything else. The rest (gearbox, clutches, axles etc) is just transmitting the power.
Hi. Torque is measured at the crankshaft. Rps does not count because is the speed of the crankshaft. Transmission does not count in this calculation.
It breaks the scale . ...That I made up 😂
Just love this videos!! Thank you!!
Once again brilliant lesson in Engineering! I liked the drag car engine, I have often wondered how they get so much grunt. Thank you