Diesel engines produce more torque mainly due to the fuel and compression ratio being typically over 20:1. Also, when you increase the stroke of the engine while keeping the bore the same, the capacity goes up and that increases torque. Hence why companies sell stroker kits for engines. Naturally aspirated F1 cars (V8/V10) produce significantly less torque (around 350nm) than many high performance cars. It makes power (over 700hp) but low torque relatively speaking. However, it doesn't need much torque to move the car due to the low kerb weight and that it exclusively runs at high RPM being a race engine.
2:35 u were slightly wrong here. Piston didn't take more or less time to travel BDC to TDC, they did in a exact same time in either cases only the piston speed is vary. At similar rpm long stroke engine would have much higher piston speed than short stroke, which limits the rpm to go higher. 2. Short stroke engines does suffer from more heat losses due to More surface area is exposed in very beginning of combustion, when piston is at TDC. This is where piston experience highest peak force due to peak pressure. 3. Long stroke engine produces more torque at lower rpm bcoz high piston speed n small valves results in high velocity incoming charge, forming a strong swirl (a turbulent motion) which leads to faster burning. It's very important to minimise heat losses as it reduce the ignition timing. Less heat loss= high peak pressure= high peak torque.
If I m not wrong ,I would like to say that a long connecting rod would result in great efficiency than short because of little angle produced at piston pin. As the push from piston gets split into two components sin and cos . Rest u understand
Really great video, I am designing 70 HP diesel engine for my project and wanted to read some stuff about bore/stroke on wiki to get introduced to the topic. This gave me much more info in such a less time. Thank you man.
Iam happy to be a subscriber to this channel since it started 3 years ago with very few and grew to be one of the great channels explaining automobiles 😀
this video explained a lot of stuff that other people missed,but i also feel that you gave over-squared engines a little to much dirt,i believe both are equal when i comes to reliability,its just usually oversquareds are used in applications were they destroy themself's to do there intended purpose while undersquared engines are used in applications were reliability is targeted or the engine is safe zoned so it cant do such thing.i believe in the end its just preference.
Unfair to Engineering Explained. You're pitting two different excellent teachers against each other. Simply take what you can from each and leave the rest.
In engines that have a cast iron block, wouldn't the undersquare design result in less heat loss, since a smaller proportion of the surface area of the combustion chamber is in contact with the more thermally conductive aluminium surfaces of the piston and cylinder head?
This video actually caused me to go and calculate everything for myself, as I have been told before the exact opposite, that longer stroke has less surface area. Funny enough, this video was correct, the one with the bigger stroke has slightly less surface area in the cylinder. Then I looked into big cylinder vs more cylinders (i.e. trucks vs sports cars) and found that with a truck's long stroke (but decent size bore too) giving around 1 liter per cylinder vs a slightly over-square engine with 0.5 liters per cylinder, the truck had around ~90% of the surface area as the sports car. Kind of fascinating and weird at the same time.
My bad, I actually forgot one part of the equation. I calculated the surface area of the cylinder walls, but forgot the top and bottom (assuming they were flat circles). This time I re-calculated and the results were actually pretty close... But the longer stroke engine actually had a slight bit less surface area (I'm talking not even 1% difference here). For this example I used the OM606 engine which has a bore:stroke of 87:84 and the M57 which has a bore:stroke of 84:90.
My Name Is Hello One important factor that he is ignoring when it came to surface area heat loss (5:27) is that the hottest part of the combustion happens at the top during combustion. The cylinder head (combustion chamber, thus more of a factor in big bore oversquare engines) is exposed to this entire high pressure/temperature charge. As the piston moves down the charge decreases in pressure and temperature dramatically. Only a sliver of the cylinder wall sees this high temp/pressure charge volume. The statement about an undersquare engine having more heat loss just because it has more surface area (due to the math involved in lengthening a cylinder) is very misleading and in most cases false.
Yeah but 9.0l stroker out of 8.4l viper does produce more tq since piston stroke is longer idk I learn about this stuff in school and come here where you say that engines with longer stroke produce the same tq as the ones with shorter stroke
How does cylinder centre distance / bore spacing impact the ability of an engine's ability to grow in terms of further increases in bore and stroke? For example could a 4-cylinder 895cc engine with a 72mm bore x 55m stroke and a 93mm cylinder centre distance have a greater potential of growing larger compared to say the Suzuki G with its 84mm bore spacing at 1.6-litres or a 4-cylinder version of the BMW M20 6-cylinder with a bore spacing of 91mm?
4:40 sports car accelerates 0-60 "that fast" because they have more 'Torque'?? The most stupidest answer I have ever heard.. It is the power of the engine that matters, Not torque!. It is the "Torque seen at the Wheel" that determines the acceleration of vehicle, Not torque seen at the Crank shaft!!! Wheel torque highly depends upon "Gear Ratio" of transmission and very little on engine torque. Do more research before fooling innocent people. And yes, longer piston stroke allows greater expansion of burnt gas, producing more "Torque". 4:05 Your imprudent assumption of constant pressure exerted on piston head throughout the stroke length is completely BS!.
Can u tell me about my engine, I have a 2022 Suzuki GSX-S750. I think it has a 4 cylinder Big Bore Short Stroke, over square. The only new update to this bike is Suzuki shortened the final gear ratio while adding more top-end power so u can hit same top speed. $8550 and will do 0-60 in 3.5 but top speed is 144 MPH. I’m at the 🇺🇸🐉Tail of the Dragon🐉🇺🇸 318 turns in 11.6 miles no side roads, 10 years flawless victory.
Yep. Makes sense why Toyota's last forever. Inherently balanced strait 6, undersquared, plus geared cam, and components. I'm not surprised they switched to engines that grenade after a few 100k
Great video 👍. But u didnt conclude why do long stroke engines in general have more torque . And how is the pressure same in both the cases( i always assumed the force to be same 😁)
@@UntangleClub PLEASE DO ANSWER. i m confused that--- "if same displacement under and over square have same torque"! 1) So under square engines are used in heavy vehicles because it gives greater amount of torque in lesser rpm? 2) and over square engines get torque later the rpm? 3) so that we have to get to a certain high rpm in oversquare engines to achieve higher torque?
@@kartikwondo6690 if u want power u need to sacrifice torque..but torque can be compensated by gear ratios..when talking about cars its not all about the engine there are also other components like the transmission and differencial
I want to know sir. During running the engine. The piston speed in cylinder constant or increasing the speed when the speed of the piston in cylinder are increas or constant
Actually y royal enfield produces higher torque. All coz of that long stroke ryt.??? But then you said even a less stroke engines can also produce the same torque, then y does other sports bike doesn't produce as much torque on a lesser rpm like royal enfields does.??
@@ninemilliondollars Yes, you are right. I also have a Honda Blackbird 98. It is crazy compared Harley. I enjoy ridding them both. they are so different.
Nice vid.Under square engine does produce more tourqe as more leverage on crank vs square our over square why do over square acceleration faster because rpm vs square or under square engine.over square has more piston area which puts more load and wear into main bearings vs square our under square engine.Over square get rid off heat better due to larger bore where under square have friction power loss compared to square over square engine. Peace
I think the force will always be multiplied with the distance on this principle only the torque wrench works in the same manner we can expect the torque to be more in undersaquare engines compared to overquare engines
It's true that as length of stroke increases the leverage increases giving more torque multiplication but there's one thing which can't be missed either. As you said about torque wrench, let's take that example. The torque applied by same torque wrench differs if it is operated by an adult or child, the only reason is, both apply different amount of forces. Similarly when considering for Same displacement, as you increase stroke area of piston crown decreases, so the pressure of combustion get's less area to act decreasing the resultant force pushing the piston. Hence torque applied is same as torque applied by adult using great force but with short wrench is equal to that of a kid using less force but with way long wrench. Hope it answered your question.😄
Hey please help me with this Over square go to a higher rpm And these type of engines are in F1 cars They use petrol as fuel While trucks use under square engines they use diesel as fuel Diesel requires higher pressure for ignition while petrol is uncontrollable at high pressure so they use spark plugs Trucks need torque more than horse power so they have undersquare engines . I think the bore and stroke ratio is mostly related to type of fuel used Diesel has higher energy than petrol but diesel engines need to be better sealed I would conclude that Petrol over square engines will produce more power and diesel under square engines will produce more torque
@@pranjalsharma479 first is you will have to change your parts like piston, valves, cam and crankshaft to lighter ones like forged alumnium kind so that it won't rupture under high rpm Then upon your need choose the supercharger or turbocharger volume
Well, all this makes sense, however, You can also use "heavier" flywheels or crankshafts to "increase" torque". Remember, heavy flywheels store energy, so once moving, it takes less energy, or horsepower to keep rotating. Torque is the twisting force that does the work. Horsepower just keeps the flywheels turning.... More horsepower is made at the expense of burning more fuel, but not necessarily produce more torque...
I am gonna add something here, comparing a diesel engine to a gasoline engine is like comparing a sledge hammer to a tack hammer! The different fuels with the Joules input to the actual joules output no matter the displacement higher joules win. More Air, more Joules + More power! I used joules for the European scientific community. But I am going to explain what Horse power is! RPM x TORQUE / 5252. Torque moves mountains, rpm moves less of the mountain at a faster rate= but the mountain is moved in the same time with the same energy.
thank you for your video but i think there is something wrong about torque T=F*R F: it's force from internal combustion while we have the same type of fuel and the same displacement so we can say that over-square engine and under-square engine have same force so the torque is diffrent please your answer it's very important
Power is dependent upon fuel type, efficiency, and and amount of fuel burnt. If fuel type is same efficiency is same, displacement and rpm is same then the generated power will be same. Power is ultimately torque and rpm. If rpm is same so will torque be different ?
torque will be diffrent because of radius we don't lose force from under-square engine for example the force of 2l fuel will stay the same in any shape :P=f/A piston. how the A piston can give us more force with relation and with same amount of fuel please can you show me some graphs how torque is the some for both engine
Good content, good animations. But this indian accent is annoying the hell out of me. Why not focus on proper pronunciation so the content is suitable for normal English speaking audience.
Diesel engines produce more torque mainly due to the fuel and compression ratio being typically over 20:1. Also, when you increase the stroke of the engine while keeping the bore the same, the capacity goes up and that increases torque. Hence why companies sell stroker kits for engines. Naturally aspirated F1 cars (V8/V10) produce significantly less torque (around 350nm) than many high performance cars. It makes power (over 700hp) but low torque relatively speaking. However, it doesn't need much torque to move the car due to the low kerb weight and that it exclusively runs at high RPM being a race engine.
This man should be a professor he just taught me all this shit in a tongue I can actually understand 😂
What’s your first language? Just curious.
2:35 u were slightly wrong here. Piston didn't take more or less time to travel BDC to TDC, they did in a exact same time in either cases only the piston speed is vary. At similar rpm long stroke engine would have much higher piston speed than short stroke, which limits the rpm to go higher.
2. Short stroke engines does suffer from more heat losses due to More surface area is exposed in very beginning of combustion, when piston is at TDC. This is where piston experience highest peak force due to peak pressure.
3. Long stroke engine produces more torque at lower rpm bcoz high piston speed n small valves results in high velocity incoming charge, forming a strong swirl (a turbulent motion) which leads to faster burning. It's very important to minimise heat losses as it reduce the ignition timing. Less heat loss= high peak pressure= high peak torque.
Each inch matters. Nailed it.
If I m not wrong ,I would like to say that a long connecting rod would result in great efficiency than short because of little angle produced at piston pin. As the push from piston gets split into two components sin and cos . Rest u understand
Very thorough explanation on pros and cons of various ways to size an engine!
Really great video, I am designing 70 HP diesel engine for my project and wanted to read some stuff about bore/stroke on wiki to get introduced to the topic. This gave me much more info in such a less time. Thank you man.
Iam happy to be a subscriber to this channel since it started 3 years ago with very few and grew to be one of the great channels explaining automobiles 😀
Thank you for supporting and being part of Untangle Club Family.
This is one of the best/simplest explanations for stoke and bore. Great video!
You forgot to mention piston speed (and its limits) as a factor : over squared engines can run higher rpm's with equal or even lower piston speeds
Equal piston speed? Does that mean the over squared and undersquared piston reach tdc and bdc at the same time? Than both have equal rpm
Or equal piston speed as they move for m/s?
@@thegipset5327 yes at similar RPM ,in both cases piston reached TDC or BDC at exact same time.
This video is for entertainment purposes not educational....
@@thegipset5327At same RPM under square piston will move faster to cover larger distance.
this video explained a lot of stuff that other people missed,but i also feel that you gave over-squared engines a little to much dirt,i believe both are equal when i comes to reliability,its just usually oversquareds are used in applications were they destroy themself's to do there intended purpose while undersquared engines are used in applications were reliability is targeted or the engine is safe zoned so it cant do such thing.i believe in the end its just preference.
In long stroke engines you either put 3 spark plugs, or change piston geometry. Like Mazda did in their engines
You explained this much better than Engineering Explained. Plus, your voice isn't annoying!
Unfair to Engineering Explained. You're pitting two different excellent teachers against each other. Simply take what you can from each and leave the rest.
In engines that have a cast iron block, wouldn't the undersquare design result in less heat loss, since a smaller proportion of the surface area of the combustion chamber is in contact with the more thermally conductive aluminium surfaces of the piston and cylinder head?
thank you so much. currently learning on engines and this definitely helps me a lot. thanks once again! subbed!
adam arlei sane here lol
Thank you 👍🙏 so much
Highly informative educative video
Thank you again
This video actually caused me to go and calculate everything for myself, as I have been told before the exact opposite, that longer stroke has less surface area. Funny enough, this video was correct, the one with the bigger stroke has slightly less surface area in the cylinder. Then I looked into big cylinder vs more cylinders (i.e. trucks vs sports cars) and found that with a truck's long stroke (but decent size bore too) giving around 1 liter per cylinder vs a slightly over-square engine with 0.5 liters per cylinder, the truck had around ~90% of the surface area as the sports car. Kind of fascinating and weird at the same time.
My bad, I actually forgot one part of the equation. I calculated the surface area of the cylinder walls, but forgot the top and bottom (assuming they were flat circles). This time I re-calculated and the results were actually pretty close... But the longer stroke engine actually had a slight bit less surface area (I'm talking not even 1% difference here). For this example I used the OM606 engine which has a bore:stroke of 87:84 and the M57 which has a bore:stroke of 84:90.
My Name Is Hello One important factor that he is ignoring when it came to surface area heat loss (5:27) is that the hottest part of the combustion happens at the top during combustion. The cylinder head (combustion chamber, thus more of a factor in big bore oversquare engines) is exposed to this entire high pressure/temperature charge. As the piston moves down the charge decreases in pressure and temperature dramatically. Only a sliver of the cylinder wall sees this high temp/pressure charge volume. The statement about an undersquare engine having more heat loss just because it has more surface area (due to the math involved in lengthening a cylinder) is very misleading and in most cases false.
@@amorag59 True
Wow I thought I knew everything already, this is so in-depth awesome
There is a lot missing here
Hey, nice video with lots of useful information.
Wow got more than i bargained for thanks!
Great explanation, I understood many things from this 10 mins video.
Superb... Superb.... superb 👌👌👌👌
very very good explanation. Thank you so much !
Very good lucid explainations and informative graphics. No nonsense just pure gyaan👌
Yeah but 9.0l stroker out of 8.4l viper does produce more tq since piston stroke is longer idk I learn about this stuff in school and come here where you say that engines with longer stroke produce the same tq as the ones with shorter stroke
Yes. But then it's not the same volume anymore is it?
How does cylinder centre distance / bore spacing impact the ability of an engine's ability to grow in terms of further increases in bore and stroke? For example could a 4-cylinder 895cc engine with a 72mm bore x 55m stroke and a 93mm cylinder centre distance have a greater potential of growing larger compared to say the Suzuki G with its 84mm bore spacing at 1.6-litres or a 4-cylinder version of the BMW M20 6-cylinder with a bore spacing of 91mm?
Does petrol engine comes in under squar engine..??
Only you are saying original truth.thanks
4:40 sports car accelerates 0-60 "that fast" because they have more 'Torque'?? The most stupidest answer I have ever heard.. It is the power of the engine that matters, Not torque!. It is the "Torque seen at the Wheel" that determines the acceleration of vehicle, Not torque seen at the Crank shaft!!! Wheel torque highly depends upon "Gear Ratio" of transmission and very little on engine torque. Do more research before fooling innocent people. And yes, longer piston stroke allows greater expansion of burnt gas, producing more "Torque". 4:05 Your imprudent assumption of constant pressure exerted on piston head throughout the stroke length is completely BS!.
Very well made video
Can u tell me about my engine, I have a 2022 Suzuki GSX-S750. I think it has a 4 cylinder Big Bore Short Stroke, over square. The only new update to this bike is Suzuki shortened the final gear ratio while adding more top-end power so u can hit same top speed. $8550 and will do 0-60 in 3.5 but top speed is 144 MPH. I’m at the 🇺🇸🐉Tail of the Dragon🐉🇺🇸 318 turns in 11.6 miles no side roads, 10 years flawless victory.
Can I conclude that whether performance vs reliability in general?
Please make more videos love your explanations!
So basicly over squares produces more power but under squares are more reliable and cheaper?
Yep. Makes sense why Toyota's last forever. Inherently balanced strait 6, undersquared, plus geared cam, and components. I'm not surprised they switched to engines that grenade after a few 100k
Its worth ten minutes in gold.
You are a genius...
Great effort brother..
Wowww excellent video.. Please make such video, nice channel
These are fantastic videos. Keep them coming!
the research is true!
Great video 👍.
But u didnt conclude why do long stroke engines in general have more torque .
And how is the pressure same in both the cases( i always assumed the force to be same 😁)
Gran Turismo 2 brought me here :)
Excellent vid mate - thank you!
beautifully explained
Thanks for the thorough explanation. Looking forward to more videos!
More to come!
what about square engines. nobod y discsses those
Good explanation! Keep it up!
Informative video, good work.
Excellent presentation.
I just subscribed!
Great video
This guy explains in a 10 minutes video better than my lecturers in the whole semester
Thumbs up to this
Cool video but voice is unclear and fast for me. But I made Like and subscribed. Thank you 😊
awesome video. thanks
Interms of top end race which type of engine is prepare for that kind of race
Over squares
@@UntangleClub PLEASE DO ANSWER.
i m confused that---
"if same displacement under and over square have same torque"!
1) So under square engines are used in heavy vehicles because it gives greater amount of torque in lesser rpm?
2) and over square engines get torque later the rpm?
3) so that we have to get to a certain high rpm in oversquare engines to achieve higher torque?
@@kartikwondo6690 if u want power u need to sacrifice torque..but torque can be compensated by gear ratios..when talking about cars its not all about the engine there are also other components like the transmission and differencial
@@gee_elgaming21 so this means my bike torque can be altered by changing sprockets
@@kartikwondo6690 yes but ull reduce power/top speed
Very informative 👍👍👍👍
Very well explained and also you nailed the myth regarding torque. 👍
i dont know what you are saying but i support it
superb bro...
yes but diesel engines have bigger compression ratio....
Perfect👍
I want to know sir. During running the engine. The piston speed in cylinder constant or increasing the speed when the speed of the piston in cylinder are increas or constant
Great informative video, I learnt a lot! Thanks!!
Workfull video
Well DONE!!!!!
Nice explanation bro
Good English good job
Super explanation
Hence, thanks a lot man
How about the lpg if it in oversquare engine? Can it be powerful than ususal?
Actually y royal enfield produces higher torque. All coz of that long stroke ryt.??? But then you said even a less stroke engines can also produce the same torque, then y does other sports bike doesn't produce as much torque on a lesser rpm like royal enfields does.??
Well, my Harley Davidson Sport Glide sure has more power at 3000 RPM than a Suzuki Hayabusa at 3000 RPM :-)
True, but depending on gear ratios, the Suzuki might rev to it's equivalent power rpm faster than the Harley will get there.
@@ninemilliondollars Yes, you are right. I also have a Honda Blackbird 98. It is crazy compared Harley. I enjoy ridding them both. they are so different.
Thanks bro
What is W.D...?
Work done
The car get 0 to 60 produces high bhp when only rpm accilerates😂😂
Long stroke = elephant
Over bore = cheetah
Nice vid.Under square engine does produce more tourqe as more leverage on crank vs square our over square why do over square acceleration faster because rpm vs square or under square engine.over square has more piston area which puts more load and wear into main bearings vs square our under square engine.Over square get rid off heat better due to larger bore where under square have friction power loss compared to square over square engine. Peace
Excellent.
Thank you.
great job - I learned a lot.
I think the force will always be multiplied with the distance on this principle only the torque wrench works in the same manner we can expect the torque to be more in undersaquare engines compared to overquare engines
It's true that as length of stroke increases the leverage increases giving more torque multiplication but there's one thing which can't be missed either. As you said about torque wrench, let's take that example. The torque applied by same torque wrench differs if it is operated by an adult or child, the only reason is, both apply different amount of forces. Similarly when considering for Same displacement, as you increase stroke area of piston crown decreases, so the pressure of combustion get's less area to act decreasing the resultant force pushing the piston. Hence torque applied is same as torque applied by adult using great force but with short wrench is equal to that of a kid using less force but with way long wrench.
Hope it answered your question.😄
Hey please help me with this
Over square go to a higher rpm
And these type of engines are in F1 cars
They use petrol as fuel
While trucks use under square engines they use diesel as fuel
Diesel requires higher pressure for ignition while petrol is uncontrollable at high pressure so they use spark plugs
Trucks need torque more than horse power so they have undersquare engines .
I think the bore and stroke ratio is mostly related to type of fuel used
Diesel has higher energy than petrol but diesel engines need to be better sealed
I would conclude that
Petrol over square engines will produce more power and diesel under square engines will produce more torque
@@pranjalsharma479 first is you will have to change your parts like piston, valves, cam and crankshaft to lighter ones like forged alumnium kind so that it won't rupture under high rpm
Then upon your need choose the supercharger or turbocharger volume
@@kuldeepgowda9508 for what
Depends on engine rpm,The torque is equal.Just different approaches
Interesting video.
What did he say?
Slow speed engine is always supercharged or turbo charged as it take more force to start
Respect
undersquare is efficient
Thanks 😊
Well, all this makes sense, however,
You can also use "heavier" flywheels or crankshafts to "increase" torque". Remember, heavy flywheels store energy, so once moving, it takes less energy, or horsepower to keep rotating. Torque is the twisting force that does the work. Horsepower just keeps the flywheels turning.... More horsepower is made at the expense of burning more fuel, but not necessarily produce more torque...
👌👍
I am gonna add something here, comparing a diesel engine to a gasoline engine is like comparing a sledge hammer to a tack hammer! The different fuels with the Joules input to the actual joules output no matter the displacement higher joules win. More Air, more Joules + More power! I used joules for the European scientific community. But I am going to explain what Horse power is! RPM x TORQUE / 5252. Torque moves mountains, rpm moves less of the mountain at a faster rate= but the mountain is moved in the same time with the same energy.
thank you for your video
but i think there is something wrong about torque
T=F*R
F: it's force from internal combustion while we have the same type of fuel and the same displacement so we
can say that over-square engine and under-square engine have same force so the torque is diffrent
please your answer it's very important
Power is dependent upon fuel type, efficiency, and and amount of fuel burnt. If fuel type is same efficiency is same, displacement and rpm is same then the generated power will be same.
Power is ultimately torque and rpm. If rpm is same so will torque be different ?
torque will be diffrent because of radius
we don't lose force from under-square engine for example the force of 2l fuel will stay the same in any shape :P=f/A piston. how the A piston can give us more force with relation and with same amount of fuel
please can you show me some graphs how torque is the some for both engine
does these engines have the same pressure
In the title it is "its" not "it's", gosh!
But undersquare engine produce more torque on lower rpm and proven on dyno..
😘
an indian
Good content, good animations. But this indian accent is annoying the hell out of me. Why not focus on proper pronunciation so the content is suitable for normal English speaking audience.
Engine बोर स्ट्रोक हिंदी में
I know why she left me ...😂😂😂😂
Im sorry but his accent is a little too strong 😂
Hehe haha