Why 21,000 RPM F1 Engines Are Impossible

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With an engine revving at 20,000 RPM this piston has a mass of 2.5 tonnes. It accelerates from 0-60 miles per hour in 0.003 of a second. And it pulls 10,000 G.
And this is what 20,000 RPM sounds like - it’s Mark Webber driving a 2006 Williams with a Cosworth CA2006 and it’s the highest revving F1 engine ever.
It’s been almost 20 years since this engine was released, so why haven’t F1 engines - or any engines for that matter - gone above this magical 20,000 rpm?
Well, it’s more difficult than you might think, so today I’m going to explain why it’s almost impossible to engines to rev over 21,000 RPM.
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#F1Engine #Piston #Revs

[@bythelee]

NONE of the thermal or stress issues are a deal breaker. Having worked in F1, analysing stresses in pistons and conrods and crankshafts and valves, I'm quite sure everything could easily run much faster - 30,000rpm would be no problem, particularly if exotic materials are allowed (like aluminium - beryllium). Turbochargers in humble road cars can hit 100k rpm while red hot... The killer factor is time. Higher RPM means less time per cycle, but the physics of fuel combustion are "fixed", in that flame fronts take finite time to propagate. The flame-shooting injection is a great idea - an advance on Alfa Romeo's "Twinspark" idea that used two spark plugs to start two flame fronts in the combustion chamber. The second problem is keeping everything synchronised. While the components can be designed to survive the loads and stresses, keeping the valve timing synchronised with the piston motion is harder than it might seem. (Quite apart from the problem of "when to start combustion" to get an optimal power output from the cylinder (fire too early, combustion works against you. Fire too late, most of the power goes out the exhaust. Ignition advance is a huge field all to itself. But I digress.) Because, nothing is rigid, and everything is flexible. And twistable. V12s and V16s have much longer crankshafts and camshafts, and will twist along their length, resulting in some very serious timing errors in the cylinders remote from where the shafts are linked together. Various efforts to deal with this include using link gears at both ends of the engine, or putting them in the middle. Which brings their own problems with "forced" positional control, that can induce their own breaking loads. This can all be engineered around, not least via novel valve technologies. But to even be aware that everything is flexible, and avoid the typical "rigid body" thinking that seemed to afflict everyone else working in the field, is a challenge in itself. For those that doubt if I know what I'm talking about, take a closer look at the bending crankshaft animation at 8:03. That is NOT showing "stress" (so, we don't even have to debate whether it is Maximum Principle Stress, or Von Mises stress, or some value of fatigue alternating stress - ALL of which MIGHT be the one dominating "failure".) It is showing a colour contour map of DISPLACEMENT. Because, the entire "red" part of the crank does NOT have similar stress - that would be concentrated at the fillet between crank web and big end... certainly not distributed equally over the whole section. Worse than that, the deformation is created by moving the centre main bearing while holding the mains at each end - a totally false load case that simply never happens in reality. At least, not to the extent it is shown here. Some movement is possible because these bearings are oil film (journal) bearings, and the oil film thickness allows a small amount of movement. But this animation is not intended to show that, since displacement at the centre WOULD cause movement in the end bearings too - the crankshaft stiffness forces that. One of the reasons I gave up doing what I did, was the disparaging remarks about being "the pretty pictures department" by folk that did not bother to look at my track record of "ZERO in-service failure" of any part I ever worked on. Sigh. But sadly, even 20 years later in 2024, it seems not only has nothing changed, but the "pretty picture" is not even a valid picture at all, but something created purely to look pretty. Sigh. TMI but for those still interested, "zero in-service failure" means inifinite life while in use in the engine. NOT "unbreakable parts" (you just have to subject them to loads they never see in service, to get them to break). This included redesigning finger followers that broke in 10 minutes, and conrods that snapped in an hour. All of these became "infinite life" parts that could last forever, just by fettling design details. And, making them lighter for better performance at the same time. For me, durability usually meant removing redundant material, and sometimes redistributing material, to better disperse loads (and hence stresses) throughout the structure. I never had to fix anything by adding any material to it. Which is contrary to intuition, and is the "go-to" response of about 99% of others doing this kind of work. "Beef up the weak bit" is NOT a good thing to hear. Just like the crankshaft that drew envy because it NEVER broke, not only lasting an entire race season, but also having the smallest main bearings of any crankshaft on the racetrack. (and smaller mains meant less parasitic torque was drained from the power output, giving more BHP at the flywheel...) But smaller bearings mean a huge increase in stress concentration, making it much more difficult to endure the loads any crankshaft has to survive. Anybody else that even tried to match our bearing size, never finished one race. When you get a handle on engineering, and materials, and stresses and strains, and loads, and resonance, and vibration, and heat transfer and temperatures, and... then designing engine parts for conditions thought impossible, becomes quite possible. There certainly are limits. Yield strengths of materials, for one. And when you factor in that the strength depends on temperature, too... But rather than get sidetracked further on "strain rate sensivity" and why F1 pistons survive stresses more than four times higher than their yield strength at operational temperature, just know that we are still quite far from reaching those boundaries with designs at 20k rpm. I mean, 99% of the piston is not even close to failure. It is the 1% detail problem where stresses concentrate that start the cracks that lead to failure. Same with that crankshaft. The challenge is fettling the details WHERE THEY MATTER. Sorry for the essay. Thanks for reading.

[@estebannegrete7662]

Thanks for the writing. Fellow mechanical engineer here... one that knows why adding material to the most stressed point of a part doesn't work ;)

[@tomvoorhis7541]

Thanks for the essay. I appreciate the insight.

[@David_Crayford]

Thank you for your insight. It appears we not only have to deal with stress on engines - but also the stress on engineers!

[@katchF22]

Mass doesn't change with velocity, the piston doesn't magically become 2.5 tons. If you're talking engineering you absolutely have to be precise with your terms, man

[@justaperson3119]

Technically, mass does change with speed, but not by much

[@christophersilver1902]

It's still sorta accurate, tons is a weight which is a force not a mass.

[@Parc_Ferme]

Are you asking too much, they use Imperial to talk about a sport that is metric standard.

[@bowez9]

Short ton, long tonne or metric ton?

[@mdb4879]

He's not explaining things for engineers to understand. He's explaining things for the layman to understand. No need to be pedantic.

[@TheNecromancer6666]

The main reasons are actually the speed of the flamewall starts to be too slow, the combination of high compression and ultrashort stroke reaches mechanical limits, and the extremely narrow gap between head and piston at TDC prevents a clean burn. The mechanical load is a problem that is solvable.

[@Colby_0-3_IRL_and_title_fights]

Yep deflagration is too slow of a combustion method at this point. Detonation could help if an internal combustion engine could make it work like a pulse detonation or rotating detonation engine in aerospace.

[@qasimmir7117]

Yes, absolutely correct. There is a thermodynamic limit to how fast the fuel mixture can burn and expand.

[@brynfisher8019]

Honda did 22500 in the 60s with the rc116. Try again

[@TheNecromancer6666]

@@brynfisher8019 Read what I wrote again. And then you can answer for yourself why the RC116 might have just worked. While the 300cc cylinder of an F1 V8 or V10 would not.

[@chitlitlah]

@@brynfisher8019 Formula 1 engines are much larger than 50 cc. Try again.

[@Turnipstalk]

Minor points: No the mass of the piston is not 2.5 tonnes, it hardly changes at all until near lightspeed. The force on the small end and the big end is about 25kN maximum. It's a lot but these bearings are of materials that can take it. The temperature of the engine is nowhere near 2500C! That is the maximum temperature of the burning gases - above that the products of combustion start to dissociate back to oxygen, hydrogen and carbon and that sets a limit. And it's the same for all engines. One of the main limits on piston speed is maintaining lubrication of the cylinder wall as the rings run over it. Note it's piston speed not rpm. And the real limitation is flame propagation speed. It's not good going fast if the fuel is still burning when the valve opens. So 20000 rpm is meaningless of itself. What matters is piston speed and combustion chamber size (small chambers allow all the fuel to burn faster). Maximum piston speed is pretty constant across engines and in fact it's roughly the same in a marine engine with a 2.5 metre stroke and a car engine running at moderate speed. Small engines can exceed 20000rpm, big ones cannot get near it. For F1, the cylinders tend to stay in roughly the same size ballpark. But in the 1960s the Honda RC166 with its 6 cylinder 250cc engine was achieving 18000 rpm with a 31mm stroke, and if it was built today with modern materials and all the benefits of CAD, FEA and better machining, an engine with the same dimensions could go way beyond 20000 rpm. It would need a lot of computer control to make it usable, though.

[@Mr6Sinner]

Reinforcing my past decision to unsub from this channel...

[@kaustavkapur5532]

he never said that the piston's mass is 2.5 tonnes. He says its weight

[@Mr6Sinner]

@@kaustavkapur5532 it says mass in the description

[@Turnipstalk]

@@kaustavkapur5532 Equally incorrect.

[@lenmetallica]

The fact that this video is still live after all the inaccuracies and wrong information speaks louder than the mistakes themselves.

[@Prelude610]

The video never actually answered the question. It pointed out the difficulties of running at 20,000 rpm, but did not actually tell us why it could not go higher.

[@procatprocat9647]

That's because it isn't a real limit. - You could make the pistons smaller to reduce their mass. - Materials science is constantly developing. - So are design analysis techniques.

[@rednezz]

Velocity and size of charge of the air fuel mixture can also limit how high the rpm can go. I had always heard they couldn’t go beyond 20k rpm because they couldn’t get the air fuel mixture in the chamber any faster. I had heard at 20k rpm they couldn’t over come the pressure wave the intake generated to go beyond that limit.

[@brynfisher8019]

​@@rednezzHonda did 22500 in the 60s with the rc116

[@rednezz]

@@brynfisher8019 Yes, for sure. I was just stating the 20k limit for the formula one engines was not due to G forces but more due to intake limitations. I am sure without any rules that put boundaries on the engine, intake and exhaust design those F1 V10’s would surpass 20k rpm.

[@Evanijoe]

The answer is still regulations. You still have things like budget, fuel flow limit, reliability, etc.

[@dalyxia]

Short answer: mechanical stress

[@AndrewTSq]

but we had 2 strokes rev higher?

[@kmanrox]

Thank you

[@Raziel1984]

short simple answer: to much "brrrrrrrrt" engine goes "boooom"

[@mandrakejake]

@@AndrewTSq a common misconception. 2 strokes sound faster but typically rev less. Honda's RC116 50cc 4-stroke (from 1966!) can rev to 21.5kRPM.

[@mrmedium7984]

@@AndrewTSq 2 strokes traveled half the distance before combustion

[@benjaminshropshire2900]

An interesting side note: it's not uncommon for the massive diesel engines on cargo ships to be 2-cycle, but that's at least in part because they run slow enough to be able to effectively replace the exhaust with fresh air via blowers (which they have the room for) and that also allows them to not run oil mixed with the fuel (which might not be as big a deal given the fuel they run isn't that much different in weight than motor oil).

[@reetspetit]

Also means you can run them in reverse easily so can dispense with a gearbox. I digress....

[@filipruml]

In weight? What does that mean?

[@reetspetit]

@@filipruml think they're referring to the viscosity of the oil. They used to run "better"/lighter grade for manouvering for better stop/start/response and then something almost akin to tar for once at sea and full speed.

[@lucasandri5462]

They're also very efficient

[@benjaminshropshire2900]

​ @filipruml e.g. "30 weight" oil is a common motor oil. It mostly refers to viscosity.

[@dirtygarageguy]

Is this a challenge on how to get as many details wrong as possible in 13 minutes?

[@davidg3944]

Ooh, -burn-...

[@mitchellsteindler]

You made it out to seem that there was a reason that specifically 20,000 rpm is the limit.

[@Lobo-tommy10]

Right? Like a sound barrier.

[@deadprivacy]

All of things in the video create that barrier. Taken to the limits across the board , its the rev speed where you cant get any higher. Driving something at speed with a reciprocating mass tops out around there. You can goi a little faster with a rotary engine but heat soak becomes a big issue and your limited ti around 20000 for anything resembling reliability.

[@mitchellsteindler]

@@deadprivacy no they dont

[@dr.hugog.hackenbush9443]

The only problem is that they DID 20K rpm... It CAN be done. Honda had a roadrace bike that would rev to 22K rom in the '60s.

[@Noise-Bomb]

yes, as stated in the video but never 21000 RPM

[@AndrewTSq]

@@Noise-Bomb but if it went to 22k rpm, I am sure it must have been doing 21 on the way up...

[@SimonBauer7]

thing is the bike pistons are smaller and lighter, so higher rpm is possible.

[@hugo.thefrenchie]

@@AndrewTSq a bike engine went to 22K, NOT an F1 engine as was specified

[@bobbobert9379]

​@@AndrewTSq nope, according to this video there's a discontinuity in the graph at 21000 and no where else

[@syntropy3020]

Frame front velocity of the fuel is what determines rpm limit. Different fuels have different flame front velocities, and thus different rpm limits for the same engine.

[@pauldonnelly7949]

No mention of the Honda air cooled, conventional valve springs, sixes of their racing bikes in the 60's, that routinely reved to 23k rpm? Relevant as they won at least 2 world championships and remained reliable. Also no mention of the, again Honda, CVICC system of the 70's? Strange because it is exactly the system you describe as new in 2015...

[@Paul58069]

it was actually the CVCC system :), but I was thinking the same !

[@MrAdopado]

That only works because of the smaller size/capacity. There are lots of engines that can rev way more than 20k ... they are in model aeroplanes. This is because they are very small. By the time you get up to the sizes needed for an F1 engine you are reaching the limits.

[@jasonsmith4902]

@@MrAdopado This destroys the argument about thermodynamic limits of combustion they were having above doesn't it?

[@MrAdopado]

@@jasonsmith4902 There is a limit of combustion ... the speed of the flame front is fixed so though it has time to zip across a small combustion chamber it doesn't have time to completely fill a large combustion chamber so only a partial burn is achieved and efficiency is lost. That's why it's possible in small engines but not in engines of the size needed for Formula One.

[@gbreslin6635]

Yes, Japanese bike engines have always been far ahead of car engines. Car manufacturers have always gone for image, no matter what the image.

[@TheHypnotstCollector]

F1 engines were touching 22,000rpm in c.2006. Saw it on TV. The tach touched 22K from time to time,

[@JTTTTT850]

Same idk why the media acts like it never happened.

[@geniferteal4178]

​@JTTTTT850 thanks. I was wondering this.

[@chuckschillingvideos]

Was that under acceleration or because of downshifts? I don't remember seeing 22k engines at the time.

[@TheHypnotstCollector]

@@chuckschillingvideos They were Reving and Shifting. Vrooom. Find some F1 races from the time, the sound alone is therapeutic....

[@chuckschillingvideos]

@@TheHypnotstCollector Oh, I know all too well what F1 once sounded like and what they abandoned. I was just never a tach watcher back in the day. Don't know what you've got till its gone, right?

[@TheSnivilous]

15 seconds in and you're killing me. Mass isn't changing, force is changing. There's no extra "stuff" just because it's accelerating so quickly.

[@Colby_0-3_IRL_and_title_fights]

The faster Usain Bolt runs, the more obese he becomes

[@jasonsmith4902]

He was referring to inertial load on the connecting rod, effective weight of the piston when changing directions. He is most surely reading a script which was poorly written to exclude this detail.

[@thekinginyellow1744]

0:10 Mass of... Beg pardon? You need to look up the definition of mass. I'll give you a hint, acceleration doesn't change it.

[@MrAdopado]

You are right of course ... but in a speedy presentation intended for mere mortals you often get these detail errors. If he had used some wording similar to "a force equivalent to pulling and pushing x tons" perhaps we could live with it ... we are not all familiar with talking Newtons!

[@thekinginyellow1744]

@@MrAdopado Because it matters. By not using correct terms, you propagate incorrect ones.

[@spacecadet35]

To quote von Braun "I have become very careful about using the word 'Impossible'."

[@Impeller_GR]

6:25 Massive blunder here, con-rod length does not influence stroke and therefore the bore/stroke ratio and engine „squareness“, only the crank can influence stroke. Rod length to stroke ratio is a whole other matter.

[@y_fam_goeglyd]

When you explained the actions of the four stroke I was taken back many years, to when I started work at a Ford engine plant (I was 17. God that was so long ago!). My dad explained it using the "suck, squeeze, bang, blow" saying. It really helped me visualise it. And as you went from one part to the next, I was hearing those words in my mind just before you used the more technical ones 😂 Fascinating stuff!

[@pjlangford1959]

My little Honda CBR250RR will rev to 21,000, it's stopped making power at 19,000 but I've seen it as high as 23,000 on the track. And that's 1990 technology and it's still going strong.

[@olafzijnbuis]

At 10:13 A complete 4-stroke cycle takes 2*60/20000 = 0.006 s You forgot that a full 4-stroke cycle takes 2 revolutions of the crankshaft. Still a very short time...

[@georgedreisch2662]

How about a episode on F-1 pre-chamber ignition? Possibly, Micah McMahan as a resource?

[@bl4ckscor3]

3:55 ah yes, rice.

[@kalebbruwer]

Yeah, doesn't really work when rotary ICE engines also abbreviate to rice...

[@JohnJohn-zh4ov]

A couple of things that I noticed in the video. Engine friction wasn't mentioned but is a key reason for not increasing engine speed further. The NA F1 engines used port-fuel injection, direct injection came along in 2014. Current F1 engines do not use TJI as described in the video, they use a passive pre-chamber as only one injector per cylinder is allowed. The stoichiometric air-fuel ratio of gasoline isn't 14.7:1, it depends the formulation of the particular fuel.

[@dirtygarageguy]

"The stoichiometric air-fuel ratio of gasoline isn't 14.7:1" - Generally speaking is it.

[@JohnJohn-zh4ov]

@@dirtygarageguy generally speaking it's not, which is why most people would use lambda or equivalence ratio to describe the chemistry of the air-fuel mixture, as it's formulation agnostic.

[@therealchayd]

Internal combustion piston engines are just insane, I mean 20,000 rpm means each piston is changing direction 666.6 times *EVERY SECOND* (at BDC and TDC, i.e. twice per rotation). Pretty mind-boggling.

[@henriklmao]

That's pretty satanic, I'm not going above 19.990 then 😂

[@therealchayd]

@@henriklmao Yeah, I really should've rounded up 🤣

[@bryce1916]

I find it kind of funny that they just created prechamber ignition for F1 even though this is ancient diesel technology where early Cat diesel engines used precups or Pre-combustion chambers that would start the burn before entering the cylinder .

[@MrHaggyy]

Well, mechanical constraints do not limit you to 20k RPM, if going above that RPM is your only goal. What limits your RPM is time. It takes time to exchange gasses, build a flammable mixture, ignite the mixture, and then you want time for the mixture to push the cylinder down. A longer power stroke will extract more energy inside the engine and send less energy down the exhaust. So it's a design balance between energy sent to the turbo/MGU-H and energy kept inside the engine. Air exchange can happen close to the speed of sound, which is close to 350m/s at ambient and close to 700m/s at exhaust temperature. Reaction time is a view µsec. The speed of the flame of 0.5-3.5 m/sec is the limiting factor. So you don't want to rev higher because it would reduce the amount of energy you get at your crankshaft at a certain point, and you want to rev even lower to avoid heat and save on mass you would otherwise need for cooling. PreChamberIgnition (PCI) was also designed to save a lot of weight. With it, you only need a flammable mixture inside the prechamber. That flame can travel through mixtures that would be too rich or too lean to ignite. In an engine, the mixture is way too lean. So you get much more air to a slightly lower temperature and pressure. An engine that runs rich to stay cool at high rpm would burn 2-4x as much fuel. Which does not work with the current fuel limit and would still be irrelevant if you could use as much fuel as you would like. It would only be interesting if the cars would be significantly (200kg

[@NLBassist]

A great vid! And it's not only about the final answer, but about all we learn in between.

[@grantfuller2016]

The more power strokes you can squeeze into a minute,( rpm ) the more power you make -But - the volumetric efficiency gets worse as you try to speed things up ( that whole getting the air and fuel into the cylinder and mixed , thing ) . There’s a point at which at which the gains by higher rpm get overtaken by the loss in volumetric efficiency . Had a tutor who said “ at 20,000 rpm pistons don’t go up and down - they just vibrate “ 😂

[@OptiVR]

Because they don't want or need to. Everything about F1 is rules and limitations, if they had to rev to 21000, they'd figure it out. ( and we'd probably see some new rotary designs because pistons are horrifically inefficient when scaled with speed, because the reciprocating load scales with revs )

[@c-ro311]

Problem is that rotaries, due to low compression ratios, massive conbustion chambers, are terribly inefficient, which is the opposite direction the FIA wants for F1

[@TheOfficialOriginalChad]

Exactly. Physics wouldn’t apply if the rules required them not to. We would have faster than light travel now too if the FIA made it a rule.

[@chuckschillingvideos]

@@c-ro311That's precisely the problem. The clowns dictating the technical parameters are, in the depths of their evil black hearts, accountants and politicians.

[@wiegraf9009]

Real galaxy brain take here

[@c-ro311]

@@chuckschillingvideos nah they aren't clowns: almost any numbskull can make a 1000 hp engine, making them efficient at the same time is what advances technology

[@Raziel1984]

so much cool things i learn from your videos :D

[@alecmillea4539]

Just commenting to support the channel and video. Keep up the great work Scott. I really hope you keep getting good viewer numbers. I’m concerned you took a major hit from the algorithm after the overdrive debacle.

[@JulianZwemer]

super informative video!

[@jools77]

Sadly, many facts presented here are incorrect

[@yazgaroth]

Very interesting! Thanks!

[@JeffSyam]

Thanks for making this video. Many times people blaming MGU for less screaming on current PU, whereas it's actually it's rev/minutes, as current PU rarely reach 13000 rpm.

[@justcarcrazy]

Ironic how the pre-chamber that was the bain of the diesel engine has now found its way into the spark-ignition engine...

[@StelaPop]

fantastic video thank you for making it🎉

[@danielc4361]

Very effective explanation about engines in general especially 2 vs 4 stroke

[@jools77]

Except he was explaining a petrol (gas) 2-stroke, and showed a schematic of a diesel 2-stroke 🤦🏻😂

[@marckart66]

I remember back when I was kart racing. I started off with 100cc karts but I never raced them. While racing with TKM and Rotax engines, I always had older 100cc engines laying about. I remember my Vortex VR / CW rotary valved engine. That engine would SCREAM. Highest I ever had it was 23,000rpm. Although I never raced it. Occasionally I'd stick on a larger rear sprocket on the colder dry days and let it sing. You really seen the temp go up. If I managed 5 laps in a row achieving 22k rpm, water temp would easily go over 70c and you'd struggle getting 20k. It was all about managing the carb and temp. Leaner engine, more power, more temp. On the really hot days I kept it rich but it was still achieving 18k to 20k. Really loved those days... I miss the smell and noise.

[@shotamakarashvili3714]

You talked about increasing RPM and therefore increasing power leading to faster laps. So it's logical to conlude that power makes the car faster... I believe it's something that needs to be explained in videos more often to people.

[@Ronilac]

Piston, in F1 engine, is changing it's mass... you can ask for Nobel Prize in physics

[@ChrisNett42]

I used to have a nitro RC car with a tiny aluminum single cylinder engine that did 29,000 RPM. That thing was awesome!!! HPI has a 3.0cc 2 stroke engine that will max out at 32,000 RPM!!!

[@jt3d867]

I remember when 11,200 rpm was the theoretical maximum limit of a 4 stroke reciprocal engines, that was in the early in 1970 s.

[@fathertimegaming17]

I've seen this video on every car and engineering channel on KZbin already but welcome to the party.

[@geemy9675]

peak cylinder pressure in a race engine 1500psi. probably even more win a race engine, so with 80mm bore that's over 15000kgf pushing on the piston

[@mcsniper77]

Two stroke engines are much more complex in theory as there are several things happening at the same time. Two strokes actually left rev lower. If you want to make the same power with a four stroke is a 2 stroke you have to spin it twice as fast.

[@caprinicus8268]

I rarely post comments like this but... At 8:18 - Aluminum has a better strength to weight ratio than steel, but is more vulnerable to fatigue, not less. Strength and weight are completely unrelated to fatigue in general. You actually picked the two most extreme examples to be wrong about - in that some steels will literally never fail due to fatigue as long as they aren't overloaded, but with aluminum any repeated load will eventually cause a fatigue failure no matter how small. Some ferrous titanium alloys can behave more like steel - but it's because they're ferrous, not because they're titanium.

[@odysyr]

A lot of talk in the comments about "mass" vs "weight" but not a lot about how that "0.003s" figure in the opening line of the video is for a full rotation of the crank and not the acceleration of the piston. That's a shame because the actual 0-60 time of the piston is even more impressive than 0.003s!

[@mrm7]

Thank you for fixing the voiceover sound. Both room treatment and the microphone

[@jools77]

The 2-stroke diesel which appears at 5.15 is fundamentally different to a 2-stroke petrol engine. Moreover, in the context of efficiency they are opposite ends of the scale: 2-stroke diesels are THE most efficient internal combustion engines ever built. @Driver61 you may also wish to licence the Phil M Karting clip at 4.42 instead of treating it as a free resource

[@olafzijnbuis]

At 06:29 The length of the conrod has nothing to do with the stroke. The stroke is determined by the offset of the taps on the crankshaft only.

[@ellipticalsoul]

It's mind boggling to me that they can even work at such high revs. Engineers who design and make these are insanely talented.

[@xrand0mx]

My first bike was a 1987 Yamaha FZR250R. It had a 19k recline and while not particularly fast, it was absolutely glorious. F1 sounds at reasonable speeds. I miss the simplicity of youth.

[@devilsoffspring5519]

Nothing says you can't ride a 'screamer' motorbike when you're old too, just try not to croak on it!

[@dadoVRC]

Two strokes don't naturally rev higher. It's the opposite. For a given displacement, a two stroke needs to have a longer stroke, since it has to open ports. 4 strokes didn't, since they breath from the valves. Since the main limitation for rpm is the mean piston speed, and since for a given speed the longer the stroke, the higher the piston speed, 4 strokes with large bore and short strokes can rev higher.

[@muttley00]

That what I was thinking. The 500cc GP bikes didn't go much past 13000 rpm, if that.

[@dadoVRC]

@@muttley00 it's a well known thing, but some people think that since the smaller mass produced 2 strokes revs higher than bigger 4 strokes they can rev higher.

[@jstogdill]

ICE are fundamentally air pumps that you squirt fuel into. For a given displacement higher rpm means more air flow and more capacity to burn fuel. They are limited by mechanical loads and flame speed. At very high rpm both of those factors come into play even for very oversquare engines. Two strokes move something approaching twice as much “effective air” for a given rpm. Turbo and superchargers pressurize the input air and effectively increase displacement for a given rpm.

[@qasimmir7117]

Yes, flame speed exactly. He didn’t talk too much about that. The thermodynamic limit of the expanding gas.

[@chuckschillingvideos]

There is no magical RPM ceiling. It's always a compromise between maximum RPM/HP, reliability, fuel and oil chemistry, cost, necessary fuel mileage and materials technology. All of these factors have to be weighed against each other in light of whatever technical rules the engine is subject to.

[@eastofmars6413]

Wow. Never imagined valves cycling 167 times per second! That blew my mind. Crazy the whole motor doesn’t explode every time they turn it on.

[@fra93ilgrande]

To think those engines idled at 4000 rpm 😂

[@WarlordEnthusiast]

The fact we can even make a 20k RPM engine is insane to me.

[@WilliamSudek]

If you get rid of valve springs,RPM is much easier. My ''street'' Ducati Panigale revs to 16500 RPM daily.)))

[@schumifan78]

Yeah, but your Pangale engine is only half the capacity of the F1 engines that were revving to 20k, and the F1 engines used pneumatic valve closure, not springs.

[@rekineke3692]

4-stroke combustion engines with a capacity above 50 cm3 per cylinder do not rotate higher than 21,000 rpm only due to the speed of flame propagation of the air-fuel mixture. The piston simply has to cover a greater distance in combustion cycles in a given unit of time than the mixture can ignite. Now everything depends on the design of the engine itself, because if the cylinder sizes are small enough, such an engine can spin up to 30,000 rpm until the piston reaches the mixture flame propagation limit again. And at no point is it related to mechanics. Because the timing can be changed to pneumatic, and the engine itself can be made of carbon, connecting rods, shaft and pistons, which will withstand short-term overloads associated with high revolutions. The mechanics of the engine itself are not the limitation, only the chemistry.

[@kwaka140]

Standard Kawasaki ZXR250, 19,000rpm redline, but happy to rev higher. The speed of flame front is so slow an engine would not work above a reasonably low rpm. However, there's something called "squish velocity". In performance 2-strokes it's critical to get it just right. I suspect it's the same in 4-strokes. The velocity of the gas in the chamber is what reduces the burn time to allow high rpm and efficiency. It makes enough difference that ignition timing can be backed off at least 5°. I'd imagine modern materials and manufacturing techniques would allow for higher rpm if allowed.

[@KellyR-qx7wn]

Commercial internal combustion engines (piston) has been available which are approaching 40k RPM. There is zero technological limitation of 21 k RPM. For an "F1 engine' the only limitation to RPM are regulations and cost.

[@answeris4217]

The equation for HP is "Torque x RPM /5252" So more RPM=More HP. You lose Torque when you have more RPM so you need to compensate somehow.

[@jameswhee]

Saw the thumbnail and got confused thinking I was at work 😂

[@mathfun1296]

I remember 37k rpm 2stroke nitromethane fueled engines in 2.5 cc displacement. Was used in control line airplanes.

[@Dammit_Jae]

Watching this is like going back to college I miss it

[@masongiles8443]

I understand it is a slow project to accomplished but I am eager to hear an update on the tunnel upside down driving video

[@extec101]

small two stroke nitro engines revs close to 45Krpm so the size and mechanical stress of the F1 engine is the limit of above 20Krpm.

[@John-jl9de]

We want 20,000 RPM engines back in F1. They sound powerful and made for some great racing. Who cares if the hybrid cars are slightly quicker, it's a show and we want the music to go with it. These modern cars sound like shit.

[@ryanakahoward5246]

I'm a minute in and I'm gna guess the sponsor today is brilliant. Edit at 3 mins in....nailed it.

[@TeunSegers]

0:12 Pretty sure the mass doesn't change because the piston is experiencing G forces. Yes, I know what he meant, but it was just wrong and this is seemingly meant to be an engineering video. Edit: I see in the other comments I wasn't the only one disappointed.

[@search4orlife]

I was looking for a track guide for Cadwell park from you but couldn't find one?

[@Curt_Sampson]

I do not understand how a piston weighing a few thousand grammes can suddenly have its mass increase to 2.5 tonnes. Is it accelerated to relativistic velocity? If so, I would imagine the engine can achieve _way_ more than a mere 20,000 RPM.

[@marguskiis7711]

there are plenty of 2-stroke engines with common lubrication system. Mixing oil with fuel is only one solution, just the simplest one.

[@BilTheGalacticHero]

Two stroke engines can't "naturally rev higher". The same mechanical and physical forces apply as in a four stoke engine. As for why F1 engines haven't revved higher since the Cosworth V8, that's pretty easy. Rules.

[@crezychameau]

RC model engine regularly run around 30.000 rpm, and some even higher, i've seen up to 45k being suggested. Granted they run on nitromethane, which burns fast, but the mechanical aspect is still here. Just a little info to temper the "absolut limit" idea that seems to be played here

[@bogeycrow1968]

You stated with 2 strokers combine intake and exhaust in a single stroke and compression and power in a single stroke. It’s actually exhaust/compression then power/intake.

[@Alexrtt92]

Frentzen said on twitter he had witnessed talks about engines reaching 23k on simulators.. in early 2000s

[@gbone7581]

Piston speed is a limiting factor that is why MotoGP has a maximum bore size to limit maximum rpm.

[@SimonWallwork]

I used to have a Rossi 21 (that's 3.5cc) that turned 28,000 rpm. Maybe more even- it was hard to measure.

[@pabloquijadasalazar7507]

6:15 Missed opportunity to have them called “squat, square, and slim.” Edit: Or “squat, square, and squished;” if you like the “sq-“ alliteration.

[@EnzoMtero]

Driving style video on kimi raikkonen please

[@IgnitionP]

6:26 Note that the length of the connecting rod doesn't affect the cylinder stroke at all, it is the crankshaft that affects it

[@MrAdopado]

True. The crankshaft affects the minimum con rod length but not the maximum so in theory it could be longer and still have the same stroke ... but I can't think why anyone would choose a longer con rod than absolutely necessary, so in that sense the crank defines the con rod length and to that extent it boils down to the same thing.

[@IgnitionP]

@@MrAdopado you should watch the video by d4a about rod ratios. A longer con rod is actually better

[@MistaWeeGee]

TGI sounds like an advancement of stratified charge which Ricardo was experimenting with in the 30s or perhaps even earlier

[@willohm5439]

At work, I'm designing something to spin at 15-20kRPM with an oil bath and it's got tons of issues - and it's not even reciprocating! I can't imagine designing an engine to go that fast

[@sirflyalot1]

I'm sorry to say your statement on fatigue in aluminium is not correct. It is just as susceptible to fatigue as steel. Even worse, aluminium does not have a fatigue limit like i.e. steel. The only reason that's not a problem in F1 is because the engine isn't expected to last very long anyway.

[@bertholdbouman3007]

BMW had an F1 engine that was just 500 rpm shy of that, it delivered 20.500 rpm.

[@maxbullinger9788]

The highest rpm ever measured in a V8 was achieved by Mercedes in the V8 at 20.232 rpm. However, this was only achieved on the test bench. The engine was never used in a race.

[@gravel-eu8sj]

couldn't mechanical stress be alleviated by running a rotary engine, just a thought and I know "Rules" but rotary engines have the potential to be smaller, lighter, rev higher and potentially more reliable and fuel efficient because of the lack of moving parts.

[@cjgordon22]

I once heard the reason they can't go over 20k is because the air moving into the cylinder was going to travel faster then the speed of sound and that would make it unstable. But that could be way off

[@richardbryant7505]

F1 engines have to run commercially available pump fuels ie what we buy at the petrol station, if teams were allowed to formulate specific fuels 21,000 rpm is easily achievable the limiting factor was the explosion happening to slow

[@petrolheadJJ]

TLDR, short stroke with long rods brings down peak acceleration of pistons. And pneumatic springs. And short service life.

[@EnzoMtero]

Driving style video on kimi please

[@fabandyou]

Would it be it be possible to premix and inject the complete quantity of fuel and air instead of having an injector and an air inlet valve? This would ensure perfect mixing of air/fuel when it’s injected, and reduce the need for one valve?

[@micsunday14]

Nothing beats the sound of a V10 at 19-20k rpm but honestly there are easier ways to make 950ps.

[@buildingracingvideos4714]

Back when they were running those ridiculous RPMs, they used injection similar to throttle body injection. Fuel and air had plenty of time to mix

[@DirtMcGert29054]

Keep in mind 14.7-1 is in mass not volume , so 14.7 pound of air to one pound of fuel

[@DChrls]

They could build supercharged 2 strokes with DI, a cyl. head with exhaust valves/camshaft and have an engine that would make great power and not burn oil or have raw fuel exit each exh. stroke.

[@nagyandras8857]

Hell no. Many 250 ccm engines in bikes had a stock street 20k redline. And whit a few mods was happy even at 24k rpm.

[@zeberto1986]

Im sure that some of the v10s and v8s hit 21-22k rpm. Im also sure that the v6s could be rev'd to over 20k but that ruins the life span of the engines and would also burn through 100kg of fuel before the race finished.