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How Do Some Engines Rev To 9,000 RPM?
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- čas přidán 23. 01. 2018
- Why can some engine rev high and other cannot?
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The Honda S2000, the Mazda RX-8, the Ferrari 458, the Porsche GT3. What all of these cars have in common is that in stock form they'll rev all the way to 9,000 RPM, if not faster. But what allows for an engine to rev to such high speeds, and why can't all engines rev this high?
This video will address five questions and subjects:
1. What is the purpose of a high revving engine?
2. How do piston speeds relate to engine speeds?
3. How does reciprocating mass play a role in engine speeds?
4. How do cars maintain flat torque curves and proper airflow at high rpm?
5. Are there disadvantages to a low revving engine?
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I love a high revving engine. Used to own a Mitsubishi Mivec from the 90's that revved up to 9200rpm and boy, the joy you get from the pull & the sound
Which Mivec? V6?
Aleksy Kabat nah, the one and only v7 engine
Aleksy Kabat it was actually the 4g92 head paired with a 4g93 block. I've tried the 6a12 on the FTO before but somehow the torque isn't fantastic on that particular chassis
You haven't heard anything unless it was a 9000 rpm 396. Ran around with one for over a year back in '73.
Hee Sing Sia yeah, I've got now 6a13 in Galant and was thinking about upgrade to Mivec heads, but it's not really cost effective
Youre one of the reasons i chose to go the engineering route in school. Being able to know so much, explain and understand all the math behind a subject and how it works is just awesome
Very happy to hear that, thanks for watching and best of luck with your education!
Rev up your engi.... Wait.....
I dont get it.. Explain plz
scotty kilmer's intro
OK Scotty !!
Lmao
Rev up your engines..... waaaaa bababababababa
Best professor I've ever had and I didn't even have to take out a loan to get you!
Haha if it’s free it’s for me!
Studying physics at uni... Enjoy watching these videos despite never even driving a car 😝
I love how I don't have a car but I watch each one of Jason's videos because he creates such fun and educational videos.
I love that you watch them as well, thank you!
so you are aware why u dont have a car after that comment i hope?
get a bike amigo they rev to 9000rpm too!
Knowledge is good, even if it doesn't directly apply to anything you currently have or use in your life!
To add to the conversation. Usually one of the first components to fail when over revving a piston engine are the rod bolts due to the mass of the pistons/rods. Connecting rod bolts will stretch under extreme stress, thus causing bearings to unseat and spin inside the rod journal housing. I've encountered this once lol.
Ok so no script or index cards or nothin? You just walk/drive around with all this knowledge on tap? God dammit Jason! How can I give you my money? Are you still selling merch?
I do have a shop set up, but I haven’t advertised it at all: teespring.com/stores/engineeringexplained
Engineering Explained Alright cool thanks I'll check it out and order something! Great job on this one with Vtec in real-time and the animations to follow up.
Not only that but he's got it all on instant recall while driving twisty hilly roads perfectly and explains it so well. I trip on my other foot when trying to explain something while walking.
T L S lmaoo exactly! Didn't even stutter. My verbal skills become nonexistent when I'm rolling through a stop sign... That's including my inner voice.
T L S if I'm still, I cannot explain anything. I have to be doing something while talking. It's most likely my ADHD.
Watching these videos is time well spent
I really enjoy your videos. I have learned a lot and even though sometimes I have no idea what you're talking about I still leave feeling like learned something. One of the best CZcamsrs without a doubt. Thank you and please keep posting!
Christopher Hepner half the time I have no clue
Christopher Hepner agreed.
Somewhat related, I love how you’re covering both Gasoline and Electric engines on this channel. Really helps when we are seeing both in the mainstream right now.
No such thing as an electric engine. AC Motor and battery pack. More simple, more powerful and more efficient than the internal combustion engine.
Um.. Laren, things that run on battery power are DC without an inverter. Sometimes more powerful than ICE, sometimes not, deepending on some factors. Don't hybrids start their ICEs if you mash the go pedal quickly, demanding a lot of oomph at once?
With VTEC which includes 1000 magical unicorns farting at once - MOOG
*a million
and its VTEC, not V-TEC
If ya wanna get really technical it's: VVTAELC
but it just doesn't have the same ring to it.
Right xD
Yeap!
Experiencing the 9000 RPM redline of a GT3 is something magical!
...imagine a 20.000 rpm (old) f1 engine :)
GT3 upshifts at 9,000 rpm are orgasmic
Absolutely!!!
I got to ride in one but never drive sadly. The sound of the climb in rpm gave me a hard-on.
I had a Yamaha r6 that reved to 17.000 it was not quite 20k but it was close
Bro ... I have a rotary in my garage right now that makes its peak horsepower at 17,000 RPM , I was like what the heck!!!
yeah a RC OS wankel or possibly NSU powered bike but no 12a, 13b, 20b or 26b would do that rpm no matter how much you clearance rotors and bearings lol
sarcasm much. Rotary can rev up to 11,000rpm. the only car engines that can rev up to 17,000 are F1 engines and even then the engine will wear out.
Even if you werent lying.... wankel engines make their peak power about 3RPM before the apex seals give out
NANI?!!! OVER 9,000?!!!
Here in Aus there was a 13b twin turbo running methanol clocked at 16,500rpm
IMO, one of the best CZcamsrs around
D'aww, thanks!
even better than fouseytube?
I miss my '01 S2000. Traded it in for a 2010 CR-V when my wife and I decided to start a family. Some day I'll get it back. There is nothing like the screaming power when VTEC kicks in and the RPMs shoot up to 9000. A spirited drive along a windy road with the top down = pure bliss.
Takumi's Trueno was able to rev to 11,000 rpm
iTZz Kittens
Well, it doesn't rev anything since the engine got blown up.
Lauren C before it got blown
It was a special engine too
it used titanium forged pistons bro
everyone quoting initial d and im just sitting here staring at the 15k rpm redline in an rx 7
I love your videos, they take me from being ricer to racer 😂
Thanks for watching!
Engineering Explained w
@@EngineeringExplained x
"So what makes it possible?" "Well, first thing i want to talk about is geometry...." oh yeah this is Engineering Explained all right XD
Another great video! Big shout out to the Mazda RX8 Renesis engine! A dyno chart for that engine will show that peak power comes at its 9k rpm redline which implies that if Mazda designed it to rev higher, it would continue to make more power. The cool thing about the rotary is that it isnt bound by a cylinder head. The manual version of the car comes with an engine with 6 total intake ports vs 4 found in the automatic trans equipped models. The 237hp 6 port engine revs to 9000 rpm (possible partly bc of those 2 extra intake ports) while the 4 port version only revs to 7500rpm and makes 191hp.
Can you do oil additives next time? Particularly liquid moly mos2 and ceratec those popular oil additives and how they work and if they will work. Thanks!
Do a video on tire age? I want to know how tires break down over time and over use, when they get dangerous, why? Do less treaded tires mean faster wear? What about super grippy tires?(Dodge demon for example)
Great suggestion, and I will likely have a video addressing very similar topics (eventually). :)
I love the talking-while-driving. Better than the whiteboard, for this topic at least.
Can't tho k of a better way to spend my break in my lorry than watch an EE video
Always so much information. Explain extremely well and clear. I'm a diesels girl so to have that little info in at the end was golden. Keep it up Jason.
The other thing about high reving engines is that it allows you to stay longer in lower gear which means it delivers maximum torque to the wheels, thus having maximum accelaration rate.
If you're ever visiting/filming in the north of England, I'll let you drive my "poor man's RWD" (MG TF). It's nothing like your S2000, only has a farty 115HP, but it has an insanely fast throttle response which makes it fun! I don't think you have MGs over there, do you?
We do not have MGs. Thanks for the offer!
its still better than my citroen ax11 60hp catcart!
we got old mgs in missouri
We used to have MGs here. I owned a 1973 MG Midget back in the late 70s
MunroM84
I won't disagree with you there! Fun car to drive, but with an engine that has the tendency to need constant care and attention. Waiting for the "Beast from the East" to disappear so I can once again dissect the engine and fix yet another issue.
I would be very curious to hear about the different strategies that manufacturers use to allow them to get to higher RPMs. So hearing how F1 cars do it, hearing how motorcycles rev that high, both would be extremely interesting.
Engineering Explained: Explained everything or details on how a vehicle works.
ChrisFix: Show you how to repair a vehicle.
Both channel are great !
I build small 2-stroke engines for a living, (with a lot of machining experience and a coupe of engineering degrees),, so when I see a young guy today getting technical, there is usually not a lot of knowledge involved, replaced by speculation and poor tribal knowledge. You give mankind hope young man. It was a pleasure to hear a young person today, talk about something they have actual knowledge of. "The more advanced a free society is, the more the citizenry has to be able to think." (Ayn Rand). Let me guess, you did not learn this stuff in today's school system. Education today, is an individual effort. Keep doing what you are doing. :)
how do you rev to OVER 9000?!?!?!
Get a bike, or get a rotary. 9k RPM is factory... 10k+ is tuned ;) .. know what I'm Saiyan
got vtec？
get yamaha r6 or zx6r , 14800rpm , max. red line 18k rpm and zx6r can easily do 16k rpm
or get a Honda CBR250RR lol you'll be at twice 9000
There's some cars that can revs higher,if you had the money go for it, if not most bikes can
I think Honda did what they could to take after DBZ. “ITS OVER 9,0000!”
They’ve been memeing since 1999 👌🏼
Jack MeOff honda motorbikes have been revving to over 9000 way before 99
Real funny name btw👌
Motorbikes Rev high. That marketing won't work because people are used to bikes revving high, but the S2K is a high revving car, and cars still rarely hit that RPM mark (excluding electric cars)
It's over 8000 was what was said in Japanese. Still good on the a2
My 1974 Toyota Corona had a 2L 18R-GR that quite regularly saw the high side of 9K rpm. Blows your piss weak meme out of the water... Same goes for all those ricer crotch rocket wannabees too...
The thing that gets me about VTEC is how they engage that secondary rocker without just snapping that actuator constantly.
RPM is kind of important.
You can't make 300 ft lbs of torque with a 2.2L Honda @ 1000 RPM. That takes more air and fuel, either by increased CID or forced induction.
Flip side of that, my 390 makes 430 ft lbs of torque but is only 280ish HP because it starts to wheeze over 4000 RPM.
The thought that a piston in an 18,000rpm F1 engine is moving slightly slower than an S2000 BRAKES MY BRAIN. Please explain in more detail. I feel like that concept is worthy of a video of its own.
So my motorcycle revving at 16k is going around the same piston speed?
🤔
INTERESTING!
a 4 cyl 600cc-1000cc engine compared to a 4 cyl with 2000cc
Yes. Your motorcycle engine has a shorter stroke, so it covers less distance with each revolution. Imagine two athletes running at the same speed, one of them around an 1/8-mile track, and the other around a 1/4-mile track. The runner on the 1/8-mile track (AKA your motorcycle engine) will have twice the rpms, even though they're both going the same speed.
Trevor Pontifex brilliant explanation, thanks
Is that why most Honda’s produce high power but low torque?, like an EM1 civic Si 160Hp and 111Lb-Ft
All naturally aspirated high revving engines have low torque. As stated, Honda 4 cylinder motors actually have good torque figures compared to other NA 4 bangers.
times changed, USA has been innovating a lot more these past years in cars while japan has slacked off while sitting on a crown for more than a decade, 300hp may seem cool maybe 10+ years ago. This is coming from a guy who never owned a muscle car yet.
On the issue of the 2 "strategies" (higher rpm vs low-end torque engines), one advantage of the higher revving engine seems to be in fuel economy during low rev range. A lower rpm/big torque engine has lots of available power without the high revs but it comes at a cost of higher gas consumption during regular driving in that low range.
The higher revving engine, on the other hand, can do just as much work when it revs up but it will not have that "on tap" availability of power that is so wasteful in the lower rpm engine and therefore can sip fuel when not in that high rev range.
But, The Piper eventually must be paid in the higher revving engine due to the higher risk of catestrophic engine failure: Higher RPM means smaller changes in wear coefficients can do more damage more quickly or more often.
Also, the traditional sense of "powerful" includes the idea that making power is effortless. Higher revving engines just seem to work harder to impress.
At high RPMs the limiting factor is usually valve-float. The valve springs cannot close fast enough at very high RPM and cause the valves to bounce and chatter. You can partially correct for the flame propagation problem with sufficient ignition timing advance.
well valvesprings can cope with very high rpm if specced right, but they are going to steal a lot of power and be much harsher to the valveshaft
Also it's not that the valves can't shut fast enough, they wont stay shut. As in they BOUNCE off the valve seat and you lose compression.
How Do Some Engines Rev To 20,000 RPM?
Kinda illustrating this with the F1 example in the video. The stroke is around 40 mm, which keeps the piston speeds less than an S2000, even though it's revving twice as high. But for street cars (with the exception of the new Mercedes Project One), rarely is 9,000-9,500 exceeded.
There electric
Carbon Reed ha ha ah lol
^ great question
Hari5g900 possibly because of a higher reciprocating mass, but don’t quote me on that I’m not exactly qualified to answer that
Flat plane crank...
Been there, done that.
Andrew Langley is that a gt 350 in ur pic?
Yep.
The inline 4 F20/22 engine does have that... nothing seems wrong here lol
My mt09s are flat plane, they sound proper boring compared to a triumph 120° crank
This brought me great pleasure. listening to that engine. Yesterday morning I was playing around with the 2001 GS-R at around 4k rpm -- just before vtec, but still a wonderful place to be.
The LS7, to get 7,000 rpm with a 7 liter engine, they used forged titanium connecting rods, special spin cast hypereutectic aluminum pistons which are both very strong and light weight, titanium intake valves and a chrome moly forged steel crankshaft to handle the speeds and loads. Driving one is absolutely amazing. The story as to why TI con rods were used is because forged steel was too heavy and Mobil 1 wouldn't be able to handle the extra bearing loads at high RPMs. It's film strength just wasn't enough. It was way cheaper to go with TI than to breach a contract with Mobil Oil Co. The collateral effects are most desirable, however. A big block that revs up like a performance V6.
Every video that you upload - is freaking awesome !!!
Thanks!!
No VTEC but the Ford 5.2L has 8250 RPM VOODOO.... I think there is a benefit in power delivery. For a car that hits the track or long windy roads, holding a gear for longer (power band) keeps you from shifting frequently as opposed to say a 6k rpm red line.
The 5.2L is such a wonderful sounding engine!!
Harold Ortiz how about the turbine engine？
Actually a better torque curve keeps you from needing to shift as much.
Buff Barnaby and what gives you the longer tq curve? The higher RPM. The longer the powerband, the higher the RPM results in less shifting.
You can have a flat tq curve but only last 2k RPM vs a flat tq that lasts 4rpm.
I had an '02 S2k and had a few great years of fun riding on the edge all the time, But I wanted to try a different approach and got a BMW Z3 3.0. It suits me better because Im getting old and lazy and I actually get to enjoy the scenery better because it doesn't matter what gear Im in it'll thrust up any grade with massive torque. I also love that feel. A Miata I had handled really well and had great gas mileage, but I got so frustrated with the lack of power, and couldnt pass anyone. I dont need to be fast, just first.
Dude you make me appreciate my s2000 so much. Glad that you've bought one so that I can now get free education about my own car.
Fantastic video dude, love the math/physics side of all this is very interesting, must have seen my previous comment 😉
It occurred to me the other day that an engine spinning at 3600rpm is rotating the crankshaft 60 times per second, is that correct Jason?
Justified it with the following: 3600 rotations/min * (1 min / 60 s) = 60 rotations/s. That's a lot of movement in one second.
there is a few different videos of the BMW S1000RR engine cut open and spinning at 14000 RPM :-)
Also valve float will limit engine speed. OHC designs also tends to allow higher engine speed than push-rod configurations. Smaller high revving engines can compensate for their lack of torque by their ability to rev higher in order to generate more power. Also, at lower revs when power is not needed, fuel efficiency is improved. The drawbacks are lack of power at low revs; more aggressive gearing and more gears are required, and possible increase in engine wear. Although high revving engines can be more fun to drive and sound better (to some people), they are more costly to manufacture.
Fun video. I thought that you were wrong about the under/oversquare thing but then I figured I better look it up because I trust you. Sure enough, I was wrong.
For some reason I had thought they were opposite. I guess that's what come from being a mechanic, but not a car guy. I fix stuff for a living but I don't live and breathe it all the time. But I do like Jason's videos - always something to learn.
So long stroke means more torque and less rev? I drove a 4.0L i6 for a few years and always wondered how a NA petrol engine with an unimpressive compressive ratio of 10.5:1 can produce almost 400nm torque at only 2500rpm
Well, it has 4L displacement, thats how
177SCmaro umm... say i have two engines with the same displacement, setup and everything but one has a bore x stroke of 80 x 90 and the other is 90 x 80. what difference in characteristics in general can i expect from the two?
177SCmaro. Yes, the idea that stroke equals more torque is persistent and entirely ignores the reduced piston area when talking about engines of the same displacement.
177SCmaro but since engines with shorter stroke are more rev-happy than ones with loner strokes so wouldn't that increase the total friction as well?
Rod to stroke ratio ?.. you dont tell about it..
A longer rod means more dwell, meaning the piston sits at TDC and BDC longer. That's good for breathing, but it comes with a lot of downsides. Sitting there longer means it has to get there quicker, so longer rods mean higher piston speeds, which means lower max RPM. Longer rods are weaker yet heavier. The extra length alone makes them heavier, but the weakness that come from extra length requires even more mass, and flinging around more mass means even more mass, and flinging all that around at higher speeds means even more mass, so it's nowhere near a linear relationship. They make the engine taller as well. Shorter rods are better 9/10 times. I'd like to see scotch yoke engines become popular someday. That'd be the best of both worlds.
Few corrections to make;
1) The AP1 only revs to 8,800RPMs, same as Toyota's 4A-GEs with factory high-rev 8.8K ECUs (most JDM ones were less at 8-8.5K, USDM was down to 7.5K.)
2) Rotary "cranks" spin at 9,000 revs, their "rotors" actually only turn at 1/3 the speed at 3,000RPMs.
I recall a Smokey Yunick quote that was approximately, "Want an engine to make power? Spin it!" To the episode: I wonder if there is a practical piston speed maximum and why. My thought is that the limit is due to mass and resulting force and not a friction issue.
Many smaller motorcycle engines rev much higher though!
some RC model engines rev even higher. The smaller the engine, the easier it is to rev high.
2 stroke engines
2 and 4 stroke engines
Smaller engine - shorter stroke - higher rpm
Well if you wanna stack the deck merely for "i've got the highest revving engine" pissing contest, I've got a 0.9cc 2stroke RC plane engine capable of over 30K rpm on nitrous.
If you want to come back to reality, I used to own a Toyota motor from 1974 that regularly saw the high side of 9K rpm.
highly appreciate the visuals.
good job
more cats plz lol 😆
one cat a video would be fun lol
meow meow
I love how you are so objective and don't introduce opinion into the videos like so many other biased people, keep up the awesome videos!
I loved my ap1 s2k for the same reason. But surprised you had a video about high revs and didn't mention bikes. Reving from 12k to a few examples revving all the way to 20k rpm
You need that turbo in there ASAP.
Corrosion37 thought he said he’s going supercharger for linear power?
You right. i just woke up. i have a dead head
Aw man, I wouldn’t turbo or super that. Don’t like the whistling drowns out the nice engine noise.🙁
Put a centrifugal turbo, best combination of the two
it will ruin the s2000 engine. Might as well keep it stock
And I thought the 7k redline in my F-150 was high...
Mel Laknanurak there I upshift in my E46 316ti
That´s crazy high for a truck
What year? My 06 king ranch revs to 5k... my Miata has cutoff at 7200, 7400 if I got a JDM ecu...
2017 F-150 with the 3.5 N/A V6 that Ford shares with Mazda
I like how you explain all of it while driving a car.
Both of my oldest sons have owned a Honda CBR250R.
The model they had is relined at 18,000rpm.
Yes it's only a 250 4cyl from the late 80s/early 90s, but to ride it around and listen to that howl is crazy.
It's the strangest feeling rolling along with 10,000rpm on the tacho and knowing it's not even in the torque yet! 😁
AE86 from initial d had 11000 rpm
That was a special TRD group engine illegal for street use since it was designed to be used in motorsports. It must be driven hard and tortured in order to maintain its reliability-.
It was a engine from a group A rally car and detuned to make it street legal
Kedar Sawant it's still illegal though lol
Kedar Sawant. You mean streetable, its simply not going to be legal in a country like Japan.
man I miss that show
*By using science! Of course!*
yeah science!
Another benefit is that your drivetrain doesn't have to be as strong. Torque is what breaks parts, but if you're relying on high RPMs to make HP rather than low end torque, they don't have to be as heavy duty. That's why 150hp+ motorcycles that rev to 15,000 rpm can still use a chain. Of course this makes swapping an LS1 into an S2000 a pain cause everything else has to be beefed up as well, lol
Thank you. Youre the only one to clear the high rev debate up
Honda engines just sing. I once drove an Acura RSX Type-S (which was a more practical alternative to an S2000 at the time) and you could feel those 8500 RPM's in your bones. Makes you smile :-)
Fun car to drive but also practical unlike these roadsters. What stuck in my memory though wasn't the VTEC step, it was the magical sound of the engine that resonated in your chest like a loud sound system.
Dennis Kapatos You should upload some videos of your Acura. Maybe some revs?
That's why I always laugh at the whole "there's no replacement for displacement" adage. Engine speed and forced induction are good replacements. 😃
but that usually only increase topend, with displacement you get a good increase overall
and a (way) lighter car
except mercedes project one
Try towing with an engine that revs to 10k.
177SCmaro You sure can boost a bigger engine, but larger engines have more mass, both in general and as Jason explained, more reciprocating mass which means more stress on components with higher revs. F1 has put out 1000hp from a 3L NA engine. That's what rpm can do. You can't rev your small block Chevy to 18,000 rpm. Like Jason said, big engines are a legit way to make power, but not the only way.
I used to really admire the S2000's high revving engine but these days I'm more of an SUV guy. A lot of these SUVs have turbocharged and intercooled diesels that not only produce lots of torque, like Ford's 2.2L TDCi that's good for 160PS and 385Nm, but they're also found in SUVs that aren't too expensive and they get pretty good fuel economy given how big SUVs are.
How can you be this smart, knowledgeable AND charismatic?
I feel decently smart. I understand everything he says and could learn the subject if I took the time, but explaining it clearly, finding the words, I couldn’t do that.
I want to know why some engines rev FASTER than others.
Matt Man that would be the flywheel. The lighter, the less rotational mass. I’m not Mr. Engineering Explained, but that’s from what I know
Lighter parts and shorter stroke...
Ultimately it comes down to the engines power vs. the engines rotating mass (flywheel included) and on modern cars the motor controller comes in as well. I drove a fairly modern BMW 1er recently and when accelerating it was revving up way quicker than with the clutch pressed in and stepping on the gas, so I guess the motor controller was in some weird mode that didn't really let me rev it...
Then you have the wankel engine, revs faster because its easier to transform rotational movement of the rotor in rotational movement of the crankshaft than the transformation that happens in piston engines, where you hay to transform a linear movement (piston up un dow) into rotational movement in the crankshaft. The differences between piston engines are due to the flywheel size and weight (depends on the irregularity degree that you want) and the general weight of the pieces.
Because of different missions! My Mercedes diesel van needs low end torque, moderate acceleration, longevity, fuel efficiency. It acts more like a tractor. An f1 car needs quickness, high hp out of low displacement, needs to last less that one year. Road going sports cars are really in the middle; performes pretty good, but designed and built to last decades. It’s all trade in offs.
Your piston engine vs one dorito boi
A few years ago online, there was a comparison of F1 vs Nascar engines (15,000 rpm VS 9,000 rpm) piston velocities were almost identical.
Jason simplified a bit, though spouting all that he did while driving = godlike ability. You can't run high rpm piston motor without the correct bore-to-stroke, big bore for breathing and short stroke for increased engine speed (square or oversquare). You'd also need lightened materials like sodium-filled valves to reduce reciprocating masses or friction. and lubrication. Then, refined airpump basics: high intake and exhaust flow, sufficient fuel delivery, strong ignition, and good timing controls.
So.. is that car from the anime series Initial D, Takumi Fujiwaras car even possible to do 11000 rpm in real life ?
Yes, in the anime it was based on (or actually was, not sure) Formula Atlantic 4AGE 20V - it's actually able to rev up to 11k.
Other real life example is Spoon Civic Type R - It had a B16B engine heavily modified by Spoon and was able to reach 11k rpm.
That sounds amazing.
I got interested in cars not long ago, so I'm not really familiar with it all just yet.
Could you please explain to me, how this is possible?
I mean, isn't it bad when an engine revs up really high ? ( I saw some videos where the speedometer for the rpm was in the red zone a lot of time.. doesn't that damage the engine ? )
I got into cars like two, three years ago, still learning stuff.
Why it's able to rev so high is explained in the video by Jason. In short, to be able to make power with short stroke you have to make up with the rpm.
As for if it's bad for engine - yes and no. The engines are designed to work with all available rpm it can reach, high rpm increase wear - it does more work, more rotations, pretty self explanatory.
Think about walking 2 kilometers and running the same distance as fast as you can - the latter will tire you out, use more of your energy, but this energy is converted into work, so you get there faster. It could be harmful to do such a thing, but doesn't have to be.
Red zone on the tachometer is just an indicator. Some cars have red revs just before their cutoff, some exactly at the cutoff point. Some modified cars have stock tachometers while having modified engine, so it actually revs higher than stock one - red zone on the tachometer loses its meaning in this case.
Thank you very much for explaining it to me ^^
So these are just different techniques people use:
high rpm = short stroke
not so high rpm = longer stroke
In the video it was said, that high rpm is preferred by car enthusiast because of the high-revving notes, but what does it mean that you can compensate it with gear ?
It's down to this single equation: HP = torque * rpm. (check last two videos for further explanation and fun stuff :) )
Long stroke engines have more torque so they don't need high rpm.
Short stroke lacks torque so it has to compensate with high rpm
Looking at it again - short stroke engines make their power at high rpm. Short gears - close ratio transmission to be precise, compensates for it, keeping the engine in the high rpm range by reducing the drop of rpm when changing to a higher gear.
My engine only goes to 11.
I ride a bike, but it only goes to 11thousand, which is actually quite low for a sportsbike
Miklós Bremer what bike? That so low... My single cylinder can rev up to 14k
I have a Kymco Quannon. It's a 125 single cylinder.
Ohh i see... Soch 4 stroke 125cc single cylinder right? Mine is Suzuki Belangr 150 it's 150cc Doch Short stroke 4 stroke engine... Your's probably have a long stroke that's why you can't reach above rpm lol
your belangr can't be superfun at lower revs, my 600cc at same revlimit is dead under 5k.
Take a 1977 Escort panel van that redlines at 5800Rpm with standard carb and 10:1 compression ratio, redline first gear at about 60 KPH. Replace 10:1 pistons with 12:1 compression ratio pistons and replace standard single barrel with twin barrel Webber with cam to suit and it magically revs out to over 9000 RPM and gets just over 90 KPH in first gear. Did that in 1984 so was way ahead of my time.
What about deck height (engine block)? Deck height has a massive part to play in fact even bigger part that oversquare design as it reduces piston acceleration. Honda and BMW have tall deck heights on their high revving engines, however their engines are relatively square. Same with the Audi V10 which is under-square but revs very high. Increasing deck height allows Manufacturers to use existing parts inventory and preserve some torque whilst obtaining high revs. In dedicated race applications such as motorcycles, dedicated race engines or F1 cars, an ultra oversquare design with short deck height allows for a lower C of G for better handling and higher overall power to weight ratio.
Because... V-TEC!!
YO!
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Give this man a cookie 👏
You need to get out more
Thank you for finally explaining this to people! I've been waiting for a CZcamsr to introduce this rule and describe why some engines can rev high and some can't.
Now, please explain to them why smaller lighter cars can use smaller lighter engines that rev higher but pickup trucks can't.
Also explain why smaller engines have to rev higher to make more power in regards to total displacement = cylinder volume x RPM and how that effects horsepower. Basically following the rule -There's no replacement for displacement.
Keep up the great work. I find this type of interaction with you much more appealing, BTW. Less mundane than the white board.
Driving around and explaining all this useful knowledge at the same time : that amaze me. You sure know your subject.
Piston velocity is something I did not know about. What about motorcycle and their crazy redline ? Must be the same as well !
Excellent video, I understand now why a bus engine red lines at 2000rpm as it has a longer stroke, but a bike engine has a short stroke and redlined at 18000rpm.
Honda 4 bangers just sound wonderful! The sound of the 06-11? Civic si with a stock intake is magical. Honda put a lot of work into making the sound very pleasing. I supercharged my 09 si and while I gained the classic screw supercharger sound, I LOST all the wonderful intake sound. The power is fun, but the audible joy of revving out a few gears isn't nearly what it was.
Best high revving engine I've heard is a Cosworth DFV at around 11,000rpm. Awesome stuff
I feel like its hard to speak about all of that stuff while driving and without the white board in front of you and while progressing logically through the math and differences between AP1 and AP2 engines. It's a testament to how well you know the subject matter. Keep the great videos coming!
Logistics operator here.
A diesel engine has more torque at lower rpm. That means less stress for the clutch with a heavily loaded vehicle, especially uphill. A clutch on a gasoline powered engine in a heavily loaded vehicle is more likely to overheat. Besides that, such lower torque curve is more attractive in the field of logistics as it seems more efficient than the gad engine that needs higher rev for the torque to be able to drive a payload uphill. As for big trucks and semi trucks: Big engines can't endure high revs, so gas is even less of a good option there.
Bottom line for me. Diesel is only a good strategy for moving goods.
I love the sound of high revving engines, but nothing beats a big old v8 that makes up for what it lacks in high RPM capability with pure sound pressure
My Honda XBX-1000 motorcycle from 1082 does 10250 RPM. 6 Cylinders for only 1047 cc
They started selling that type in 1979.
IT just doesn;t feel right to rev it over 6000 RPM, but, of course, it was designed to do so and sounds glorious when you rev it under load.
Dual overhead cams help as the valves breath the same as two larger valves but with less weight and overall lift.
high rev ranges are possible (and meaningful) on fourstrokes because they are elastic engines. two strokes, in comparison, have a very limited rev range where they create (apply?) torque. A four-stroke can create torque over a range of rpm that covers more than an entire order of magnitude. The practical result is two-fold: one, is versatility (you don't have to scream the engine when cruising) and two, is performance: the behavior of an engine at very high rpm is much more uniform and smooth between gears and it is easier to keep it at peak power.
Thanks Jason! Absolutely love the videos like this. Spent most of the video staring at the background scenery. I can't help but feel like this video was talking to me. I own both a K20Z1 & a T444E, 8200 & 3300 RPM respectively.
I like high revving engines because it gives you more freedom to use the accelerator on technical courses. It's a common scenario, you're trying to get as much speed as you can out of your car while on a straight as you're approaching a corner, but you're running out of revs. Normally you'd change up a gear to keep accelerating, but by the time you change gears, you'd be in the braking zone. Or say you're in a lower powered car and are struggling up a steep incline. On level ground, you'd change up a gear, but if you do that here, that moment you're off of power would mean a lot of lost momentum, which the higher gear would struggle to build back up to because it's less advantageous.
You can make more power either with higher-revving or with higher displacement. The high revving engines are smaller and lighter and therefore more suitable for racing cars that tend to stay high in RPMs where is all the torque of such engines. Low revving engines have heavier pistons and have more torque in lower RPMs and therefore more suitable for trucks, busses etc. The Torque on the wheel can be of course adjusted with gearing. Which means that a slightly more powerful high revving engine would still make more torque on the wheel at high RPMS than a slightly lower-powered big cc lower revving engine, but not at low RPMS, assuming that both engines are geared to have the same top speed per gear.
I think it matters for fuel efficiency vs weight of engine, a high revving engine is usually smaller and weighs less than a low revving engine producing the same power at a cost of high fuel economy
Everyone talks about piston speed nowadays when the real force behind these limitations is derived from one of Newtons laws: F = ma. It's the piston acceleration that determines the rev range, not speed. But nice talk anyways. That S2000 is a work of art.
Japanese motorcycle manufactured 250 cc Inline 4 cylinder engines which revved up to 18,000 RPM in stock form, that's pretty awesome.
Taking the 5.2 Voodoo to 8250rpm is a treat, though I rarely have the room to do it.
That's why I love my RX8, upgraded the top end is 11 grand red-line and 12 grand kill point
My cousin had a AE86 with a 4AGE 20v Black top that red lined at 10.5k, it sounded so sweet
Correction if you don’t mind. Vtec does not change the cam profile and allows the valve to open more as you stated in the video. It changes the cam angle relative to the crankshaft angle. By retarding the angle it allows more top end torque (it basically shifts the torque curve and therefore peak torque into a higher rpm range) which translates into more power at higher rpms.
VTEC (in the S2000) does indeed alter valve lift, rather than changing cam phasing (what you’re referring to). The valve lift change is demonstrated in the animation in this video.
I apologize, I actually had to stop the video after you mentioned that part and didn’t make it to the illustration. My bad, I was under the impression that it was a strict timing change and not aware that there is a third lobe and rocker arm involved.
I realize this isn't really related, but I can either raise my redline by 1000 rpm or increase my compression ratio by 1. Yes they stress different components in different ways (both would also affect piston speeds but to a different extent), and obviously require different tunes, but what would be the relative effect of each?
My guess is that the compression ratio would improve torque and power more broadly where as the rpm limit would merely allow more power at the end of the rev range. ...Though I suppose I would have to try them both to find the exact power and torque figures in this specific application.