also with a 4 valve setup the valves are smaller and lighter causing less valve float at highter rpm,allowing for higher rpms than a 2 valve setup

@EngineeringExplained

8 жыл бұрын

Yes indeed.

@XxRoflcoppterxX

8 жыл бұрын

+ChinnuWoW No. The 4 valve setup will allow for a higher redline as stated above.

@alexK661

8 жыл бұрын

+Mario S. red line is also highly dependent on piston travel, more so that valve weight

@XxRoflcoppterxX

8 жыл бұрын

alexK661 this is all theoretical stuff. Theoretically 4 valves can rev higher.

@XxRoflcoppterxX

8 жыл бұрын

ChinnuWoW well hemi has its advantages, but I would not say it's better. A major disadvantage is that a hemi cannot have 4 valves per cylinder

I learned more on this channel about engines than in school.

@erkdoc5

8 жыл бұрын

+CertifiedKilos If you didn't learn anything in school, you either didn't pay attention or you chose a shitty arts major. Of course you don't learn everything there, you would never leave if that was the case. You just learn specifics and basics which you need for a certain career, with some general education stuff that's required.

@chek1n

8 жыл бұрын

+CertifiedKilos You didn't challenge yourself with Honors and AP classes. Taking minimal education is one's choice and experience.

@AdvancedGT

4 жыл бұрын

@@erkdoc5 Well in europe we don't learn anything really about engines. The only thing they teach is the suck, squeeze, bang and blow opeation of a 4 stroke engine. But they didn't teach us anything else. Differences between diesel and petrol for example, they don't teach that. I think that's a pretty fundamental stuff everyone should know. Otherwise their mechanic will charge them for spark plug replacement ....in a diesel car.

@kg_1720

4 жыл бұрын

Lmao true true

@P0k3D0nd3M4cG

4 жыл бұрын

@@erkdoc5 tf are you talking about? If I learned 0 things about engines in HS because i either didn't take auto shop, it wasn't offered, or it didn't fit in my schedule then even if learned *1* thing from this channel, i learned more about an engine than in school.

When VTEC kicks in you get more than 7mm of lift yo.

@chaiyy9252

8 жыл бұрын

+IIGrayfoxII hahahax

@MrMagic1220

8 жыл бұрын

Actually 6.9mm of lift but close enough

@MrBusunglueck

8 жыл бұрын

+IIGrayfoxII when bmw valvetronic kicks in you get 9,9mm of lift.

@tiagoneves8072

8 жыл бұрын

+MrBusunglueck when my valve kicks in, some girls get 17 cm of lift

@MrBusunglueck

8 жыл бұрын

Tiago Neves a gril with 17 cm of lift? thats more than the average guy. shoutout to whatever transvestite youre dating.

I dont understand what he said, but I heard he said pie, so Im gonna go out and get me some pie

@blackericdenice

6 жыл бұрын

doodskie999 Are you Eric Cartman?

@rer-cilantro4008

6 жыл бұрын

why do we share thoughts about the posible interpretation of eric cartman being in this comment section

@SevenFootPelican

5 жыл бұрын

PI ! PI !

@mystictrails9994

5 жыл бұрын

One for me please...

@rizqyaqil3019

5 жыл бұрын

3.14 22/7

These kinds of videos, i.e. drawing as you go to illustrate your point , are tremendously helpful. I hope to see more of these digitally drawn videos.

From expirience, I noticed that usually 8v engines have more torque in low revs, but are not very eager to rev compared to 16v.

@danielt.9611

2 жыл бұрын

8v is fun in cities.

@DanielRevay

2 жыл бұрын

@@danielt.9611 lol true, can confirm

The saying is true, you do learn something new every day! Thanks for this Jason!

Clear, concise, informative, and no filler bullshiet. Great vid, thanks

Another advantage for 4 valve is an optimum spark plug placement, being in the middle it has the shortest flame front distance to fill chamber and having more control of timing.

4 valves and 2 valves, no 3. half-life 3 confirmed.

@krabz_oem

8 жыл бұрын

+W scott Volvo, please.

@XxGreYSh0TxX

8 жыл бұрын

3 valve Modular 4.6

@SldgeHammr

8 жыл бұрын

+XxGreYSh0TxX RIP my sparkplugs

@XxGreYSh0TxX

8 жыл бұрын

+SldgeHammr That issue was fixed long before the 3v.

@SldgeHammr

8 жыл бұрын

XxGreYSh0TxX I was referring to how stock plugs break into two to three pieces in the 3v 5.4 4.6 motors

Great video, appreciate you taking the time to put this together.

Fairly straightforward. More valves, assuming an equal piston width, means more airflow and more efficient combustion. It's cool that you mentioned the practical advantages of two-valve engines as well.

One of the reasons I love classics is the simplicity. 2 valves per cylinder, carburetor, OHV configuration etc. My 6,4 liter V8 engine is super simple, there is actually only one camshaft in the middle because OHV. Working on the engine is so much easier than even a modern straight 4.

@josebarbosagarcia550

Жыл бұрын

Ew

@lmf868

4 ай бұрын

you get less efficiency and power but for something you need to just work an cheap to maintain, 2v setup is always a good thing.

@staresce

2 ай бұрын

How old is your 2 valve vehicle?

The 2 valve setup doesn't mean it has to be an OHV engine. Plenty of engines out there with 2 valves that are OHC. At least in Europe. I prefer the 2 valve per cylinder setup. It has better driving characteristics for city driving in traffic, also easier to drive in low RPMs (~1800-2300rpm) in cold conditions to warm up the engine. To name a few. A lot of 4 valves per cylinder engines are optimized for high revs (>4000rpm) which I don't find practical or comfortable to drive in every day use. Although it can be fun on track days. Bottom line is 2 valves per cylinder is not a bad thing. It's just different and I prefer it over 4 valves per cylinder.

@zOiNhUh

5 жыл бұрын

Not to mention some Diesel engines which either retained a 2-valve layout or turned to it for emissions compliance.

@TheUchihasparky

5 жыл бұрын

Having 2 valves per cylinder may improve low end performance a tad but it's like the 1 con of DOHC, but the difference is HARDLY noticeable. I upgraded from a sohc car to DOHC of similar engine displacement and I'd say your right but it's almost undetectable. I highly advise you rethink your opinion before you make your next car purchase, as higher rpm performance is really night and day difference when I switched, and it's not like there is much fuel economy difference between the 2 cam configuration.

@raycroal

4 жыл бұрын

i hear you bro, i dont like being above 2500rpm and only once in a while do i prod it over 4000rpm

The last comment was made 4years ago and today, I've come to know the fact of airflow. Thanks for this awesome illustration.

I really like this new animation style it is way easier to understand, thank you and keep up the good work.

The animation is great. I think this opens a new world to EE. Keep working!!! Following you since 2012!

@EngineeringExplained

8 жыл бұрын

+Rodrigo Cunillé Thanks for sticking around for so long!

This new style of animation is fantastic. Far better than the whiteboard because of how much more you can do with it.

@EngineeringExplained

8 жыл бұрын

+Dylan McElveen Don't be hating on my white board! ;)

@KiwiPowerNZ

6 жыл бұрын

Some of us like the whiteboard! Getting schooled isn't the same without a whiteboard!

I love this set up of the video, also to note, it was short and to the point! Awesome :D

Great, easy to understand explanation and graphics. Answers a question I've had for a long time but never looked into it till today. I came to the right place. Thanks

valve per cylinder / effectiveness 2 = 50% 3 = 64% 4 = 68% 5 = 68% 6 = 66% 7 = 64% 8 = 62%

@user-uz9sr4jj7f

8 жыл бұрын

Well, its information from Wikipedia. I thing everythin depends of that, how the engine is made (bore, stroke, valve timing, valve opening, compression...). With every one more valve, they become smaller and faster, which mean the effectivenes of the engine is in bigger rpm, but if the engine work in high rpm become more unreliable. So thats why 4/5 valves per cyl. are the optimum for normal cars.

@713racing

7 жыл бұрын

you should teach them how curtain area fits into those answers but good job... I personally have a 3 valve SOHC mustang with a 85mm turbo... Ive been wanting to switch to a DOHC 4v setup forever, but have been trying to justify to myself just how much of a gain i will get for the money I spend! I TOTALLY acknowledge that the 4v mustang heads are better then the 3v heads, but to what degree??? add in that its a forced induction engine, and the percentage of difference becomes not so big... seeing your calculations makes me think that my money MIGHT be better spent preparing my 3v setup to run at the higher boost levels needed to equal power using the 4v heads.. IF your saying that going to a 4v head will gain me 4% edge, it makes me wonder if 4% is worth the $4000 for some gt supercar heads, or whether i should just crank up the boost another 2-3 psi to get the same effect???

@713racing

7 жыл бұрын

id like to know how this chart pans out when size of valves, and the curtain area of the cylinder head/intake valves are added in????

@badass9961

7 жыл бұрын

I would stick with your 3 valve heads especially if you have a turbo. The gain from going to 4 valve heads wouldnt be huge for the price it would cost to do it.Ive seen little 2 valve 4.6's with turbos laying down 8-900 at the tire.

@alexanderkasady6839

6 жыл бұрын

Craig Baker- Never mind this guy's lousy explanation- here's the short version: Two valves of the same combined diameter as one valve will have 33% more curtain area. Example: Two 1-inch valves have the same over-all width as a single 2-inch diameter valve, but with 33% more curtain area can inhale 33% more intake charge. A bigger bang will result. Also, with a centrally-located spark plug you'll have equal flame travel distance and time. Better, more thorough combustion. Third: 2 smaller valves in place of one big one can be placed at a closer included angle to the the other pair of valves, the exhaust valves. This lowers the combustion chamber height, lessening heat loss through absorption to the cylinder head. Heat loss is energy loss, and the less of it, the more efficiently your engine converts gasoline into heat energy that spins the crank and the driving wheels. Four: The lower combustion chamber height also allows for a lower piston crown. A flat-topped piston absorbs less heat than a pop-up piston. In a 2-valve head, the larger you make the valves the farther apart you have to lean them, increasing the included angle, and therefore also raising the combustion chamber roof. By raising the roof you create a larger combustion chamber and thus lower compression, so to offset this you have to raise the top of the piston crown. Result: more surface area through which heat is absorbed and a long flame travel path, requiring more ignition advance, which in turn leads to more pre-igniton, which, in turn, requires higher-octane fuels, i.e., 'racing fuel'. Go to a 4-valve per chamber set-up and you reverse all that- greater extraction of heat energy from a liquid fuel, more horsepower, better fuel economy, and a cleaner exhaust, and God knows, we have to keep EPA happy. Then of course you have two light-weight valves in place of one heavy one and you can use lighter, lower-pressure valve springs and reduce camshaft friction, resulting in less pumping losses. It also allows for a higher rev limit, if that's what you want, but with a street engine you need low-RPM torque to (A.) pull you away from the stoplight, (B.) pull your boat, and (C.) spin all of those ancillary drive items- a/c compressor, power steering pump, alternator while doing A & B. Racing engines with their higher-revving engines don't need to do all that, and the 4-valve per cylinder lay-out allows you to tune it for torque as easily as you can tune it for horsepower. Got that?

You know what they say: “more valves, more problems” Actually no one ever said that..

@fettaheker

3 жыл бұрын

lmao

@JayRussellDuramax

2 жыл бұрын

Many, many people say that... That's the reason why the US aftermarket is dominated by 2-valve, cam-in-block engines: They're simple, compact, light, reliable, and make power just as good - if not better - than anything with 4-valves and overhead cams.

@MaybeKian

2 жыл бұрын

@@JayRussellDuramax I hope this is a joke-😂

@JayRussellDuramax

2 жыл бұрын

@@MaybeKian Why? What do you have to say otherwise?

@platinumbrick6

Жыл бұрын

@@JayRussellDuramax because you’re wrong 🤣 4 valves compared to 2 is better in every way besides cost (efficiency, top end power,less valve float) but keep on talking about what you don’t know about

Liking the new format. Should do more similar to this one.

Great video and a nice new style with the animation!

question: why dont we make both valves semi circles and make use of more space?

@jo3sk1

8 жыл бұрын

Very difficult to manufacture

@miagi1337

8 жыл бұрын

+Anas Malas semi circles? Not sure what you mean but don't forget in the end, the valves also need to seal the cylinder. If they don't seal the cylinder well, all the torque goes out on top :P

@AMalas

8 жыл бұрын

a.k.a. miagi almost like a D shape with rounded edges...

@Chuzo1946

8 жыл бұрын

good question, I'm not sold on the manufacturing difficulty.

@Chuzo1946

8 жыл бұрын

+RedLandGaming thank you sir

It should also be noted that the fact that the valves are smaller means that they are lighter. With lighter valves, valve float is less of an issue. This means the engine can achieve higher rpm without worrying about the valves staying open for too long.

One of the best "OHC Vs DOHC" so far!

love the animation! miss your face in there though! keep up the good work!

This video reminds me why I wasn't a math major in college.

@Chuzo1946

8 жыл бұрын

bro that's like 8th grade math.

@guest98049

8 жыл бұрын

+Chuzo1946 8th grade??!! I did this in 5th grade #asianproblems

@lazydadsgarage

8 жыл бұрын

lol what math?

@heinrichklogbaum9072

7 жыл бұрын

that is so simple what is wrong with your brain?

@heinrichklogbaum9072

7 жыл бұрын

I had that stuff in 5th grade too.

OKAY I GET IT. 4 VALVES ARE BETTER THAN 2.

@1MotoXRacer1

8 жыл бұрын

+datstocklyfe Yeah well some idiots think otherwise, lol. Someone tried arguing to me about how Honda's V6 SOHC with 2 valves per cylinder was somehow better than if it was DOHC with 4 per cyl.

@1MotoXRacer1

8 жыл бұрын

+Экспертное Подразделение Диванных Войск! That first remark is hypocritical, lol. But DOHC = more power + more efficiency. Your argument = one shoe is more reliable than two because then you don't have to replace two shoes if just your one wears out. That's a little silly. There's a reason why 90% of engines made today are DOHC. SOHC is making a comeback in some situations like hybrids only because of weight and size, which the efficiency is balanced out due to the less weight AND electric motors assisting it. I wouldn't say SOHC is more reliable either since it's more simple. It all depends on the engine itself, and infinite other factors.

@alexanderkasady6839

6 жыл бұрын

Nope. Wrong again. SOHC is NOT better, as it blocks the location of the spark plug in the center of the combustion chamber roof, essential for even flame travel. The only time SOHC design allows that is as in my Mini Cooper, where the intake cam is located over the intake valves, like in a DOHC motor, but actuates the exhaust valves by way of pushrods and rockers. There is no exhaust camshaft. Otherwise, it's the DOHC motors and pushrod motors that allow access to the center of the combustion chamber roof for this important design feature. No difference in reliability between a SOHC motor and a DOHC motor, save for the floppity cam chain, and that's the same for both motors..

@SousukeAizen421

6 жыл бұрын

so the cam actuates the intake directly while the ex is actuated with the rocker arm ?, is it a smiliar system to honda's unicam that they use on their motorcycle ?

@Raise986

6 жыл бұрын

That's exactly how the unicam works

You read my mind, I was looking for this video yesterday!

Wow, when you do your explanations with illustrations, it becomes so much easier to understand everything, I wish you can do these types of explanations using those illustrations, and leave video recording to reviews, accelerations, and those stuff

The maths doesn't take into account a few things; Average lift specs. No valves sits at its rated max lift for more than a few ms. If you have 5mm of lift, your average open height is probably 2-3mm. Flow below .5mm is basically nothing and isn't worth including Pushrod peak figures are well below a small 2L peak figures , so valve float is never really an issue since it doesn't need to spin that fast to get the numbers. If you want HP, spin faster. Easy. Valve stem isn't taken into account. Valves aren't flat on their tops(or edges), so it's a tad more complicated than a cylinder for the maths

@Stratos1988

8 жыл бұрын

+wolfy9005 Those are nitty gritty details, all he was showing is the difference only in valve count while all other things remain the same. I don't think he's that much off with his math. Below 10% for sure.

@1300l

6 жыл бұрын

The thing is that 2 valves per cylinder has a more homogenous air flow on the cycle, making it easier for the piston to move. None is better it's just different design and there for different results. 4 valves is much better to extract the last drop of HP on the top end RPM, where 2 valves is better to have a more smooth engine on all RPM (even on top end). So for a city car, 2 valves can be indeed better (specially since the engines aren't design to only be driven on the redline at each gear shift). But for a track car, 2 valves is just unifiable.

I used to have a motorcycle with 5 valves (3 intake, 2 exhaust). I think they left that design because of the increased complexity of the motor though

Now this is spectacular. No bs at all, pure math! Good job!

This is a boring video. I love it. Learned so much in a pretty short video that would barely qualify as a PowerPoint presentation. This is 5 years old but it was just suggested to me and I’m glad it was.

@EngineeringExplained

3 жыл бұрын

Happy to hear it, thanks for watching Jeremy!

please do DOHC VS SOHC

@EngineeringExplained

8 жыл бұрын

kzread.info/dash/bejne/Y3uO1rWhhNLYn8Y.html

@Akshayysk

8 жыл бұрын

Engineering Explained thank you sir !!😊😁

@NazoVidere

6 жыл бұрын

DOHC = Timing belt won’t ruin your engine SOHC = Ruin you valves/head if the belt breaks There’s an easy run down.

I love it when you work with metric. I don't know imperial!

Many thanks. Finally you have proper graphs.

Clear and straight to the point. Thanks

I get the advantages of the 4 valve head, and I see how this could be applied in a static scenario as such in the video. However there are far too many other varibles that go into making a good flowing head. You have to look at valve inclined angle, the duration and lobe separation of the cam, the actual shape of the compression chamber makes a huge difference, and not to mention the port design. These all take part in making a good flowing head. Yes increasing valve numbers will increase the "useful" area, however as mentioned above, there are many other factors that contribute to making a better flowing head. Look at LS and the Hemi, those engines have proven to be some of the most powerful engines built. And they're doing it on 2 valves.

What does the math look like for 5 valve vs 4 valve? I remember that being hot for like a week. Also any idea why valves are circular? Seems like it would make more sense to make the valves irregular shapes to maximize their area/perimeter.

@SubliminalFilmandPhotography

8 жыл бұрын

The valves are circular because they need to seal properly. The seat is a different angle than the face of the valve, so when they meet it guarantees a seal every time, which is much harder to make and repair if it was say a half circle, or a square. Also, the tools used for machining when rebuilding an old engine allow for your hand to twist to get an even cut rather than trying to do it to multiple sides where the measurements of the valve may be uneven

@future62

8 жыл бұрын

Subliminal Film Interesting. I just figured that with manufacturing and machining having become as sophisticated as they are making a non circular sealing surface should be no problem. I also feel like new engines don't need to be rebuilt much (i.e. I don't think valve adjustments are part of regular car maintenance anymore), so concerns like remachining valves for a seal are a bit arcane. A lot of cars are made in high enough numbers that it's often cheaper to just replace something like an engine or cylinder head than to rebuild it. I mean for my Civic for example I can pick up a warrantied long block for like $500. Cant beat that

@callanklimts

8 жыл бұрын

+future62 curious about the significance of a 5 valve as well. Fried of mine has a ferrari 360 CS.. it sounds absolutely beautiful with the 5 valves... but is it all sound or actually beneficial?

@russell6167

8 жыл бұрын

+future62 Valve adjustment is still very much a part of scheduled maintenance. The math for 5 valve would look the same as the math for 4 valve, but you'd have 3x inlet valves instead of 2, but with smaller diameter... still they'd flow more but the complexity can outweigh the benefit.

@future62

8 жыл бұрын

Russell Hawkins I don't think I have ever owned a car that had scheduled valve maintenance. Even my motorcycle only needs an *inspection* (not even an adjustment) every 26K miles. And it revs to 11K....

Very clean video! I like the new approach! Thanks for the great explanation

GREAT EXPLANATION!!! CONGRATS!! THANKS FOR SHARING THIS KNOWLEDGE!!

One Doubt. Which one gets more fuel effiency? 2 Valve or 4 Valve?

@MEGASTRIX

5 жыл бұрын

I think 2 valves by the simple logic of less fuel going in and out. JUST GUESSING.

@TheUchihasparky

5 жыл бұрын

Depends on if the car is port injected or direct injected. Port injected 2 valve better then port injected 4 valve, but direct injected 2 valve worse then direct injected 4 valve. The reason being port injected cars have fuel come through the intake valve, so in Port inject setup u get less gas and air coming in on 2 valve setup vs 4. But in direct injection fuel amount is much more precise and having 4 valve would give better fuel economy because the computer has more control over a/f mix and the simple efficiency advantage of 4 valves getting optimal air in quicker would give the 4 valve car the edge over the 2 valve car.

what about 5v? My dads C5 A6 has a 2.4 V6 with 5V per cylinder. Still doesnt make much power.

@1MotoXRacer1

8 жыл бұрын

+Joe Barbaro over complication, and unequal exhaust and intake ports actually take power away. The 5V per cyl. was just a selling point because in 'Merica bigger is better and more is better.

@renetucker8703

8 жыл бұрын

+Violetta Not necessarily. Toyota manufactured the 4AGE engine in both 4 and 5 valves per cylinder configuration, which means that the 4 cylinders had a total of 16 and 20 valves respectively. Stock power output is significantly greater with the 20 valve configuration at 160HP, while the 16 valve produced 128HP. Albeit, the 20V engine is slightly more modern, featuring variable valve timing, but I'm sure the number of valves also played a role in the greater power output.

@darenzy

8 жыл бұрын

+Violetta Not necessarily, 5V technology was introduced on "UrQuattro" model, Audi continued to improve 5V. And in 1999 released "8L" S3 in Europe, with 1.8l 20v engine producing 224hp. Not a miracle, but that engine is capable of 450-480hp on stock internals. Also in 2002 a4 and a6 offered n/a 3.0l V6 30V that was very smooth and somewhat more efficient.

@1MotoXRacer1

8 жыл бұрын

+Darko Darenzy +Rene Tucker Was talking about that engine in particular hense the 'merica comment. Any modern variation of an engine will of course produce more power than an older variation. That's just common sense.

@keesie75

8 жыл бұрын

+Darko Darenzy No 5V's on the UrQuattro. First 2, later 4.

i always thought that the airflow is proportional to the circular opening but circumferential wall area makes much more sense now. it is where the most restriction happens so it determines the flow

So whenever someone is talking about lift with regards to an engine are they always talking about the intake and exhaust valve lift? Thanks for your help! My favorite channel by far!

The most powerful production V8 is a OHV.

@JimmyBreedlove

5 жыл бұрын

Sir Brellin 2019 Mustang GT 5.0 = 460HP DOHC // 2019 Camaro/Corvette 6.2 = 455HP OHV.................

@MiyukiSadako

5 жыл бұрын

@@JimmyBreedlove dodge demon 840hp OHV top fuel Chrysler hemi OHV also pushrod 11,000hp

@MiyukiSadako

5 жыл бұрын

@@JimmyBreedlove Hennessey venom ls7 pushrod OHV 1200hp

@JimmyBreedlove

5 жыл бұрын

MiyukiSadako The Demon and Venom are both supercharged to make those numbers lol... And 11,000hp top fuel dragster...? We were talking about production cars, you were already reaching with the Venom. I’ll throw in the 2018 BULLET Mustang at this point, 480HP N/A out of a 5.0, while you need a giant 6.4L 392 OHV to make 485 LOL, and the Charger variant of the 392 weighs 700 pounds more than the 5.0... Yikes. Pushrod cars should be light seeing as how a 6.4L is about the same physical size as 5.0 with less internal parts, right?

@bachtiarfarid9751

4 жыл бұрын

@@MiyukiSadako koeniggsegg v8 camless engine 4 valve per cylinder, produce 1350hp

why do valves have to be circular?

@Daiephir

8 жыл бұрын

+Lachlan1662 Because valves spin on themselves due to (IIRC) harmonic frequencies. So having anything else than a circle would make the valve not close and create problems.

@thecosmy1

8 жыл бұрын

+Lachlan1662 was asking the exact same question

@EngineeringExplained

8 жыл бұрын

I guess they don't, it's just an efficient shape. You don't want sharp edges as it would create a hot spot, but something rounded would work. Circles offer more area than other shapes though, based on the perimeter (circumference). Strong, efficient, even shape.

@thestug93

8 жыл бұрын

+Daiephir Couldn't one use a valve guide that would prevent a non-circular valve from spinning. I'm assuming this isn't typically done through, because non-circular valves would be hard to manufacture cheaply. I mean you can't really crank out hundreds of valves with goofy shapes on a lathe in short order.

@kamilb8232

8 жыл бұрын

+Engineering Explained It really seem like a two wide oval shaped valves would be the most efficient in this case, at least in theory. I'm curious why that's not applied.

THANK YOU! FINALLY AN ANSWER TO SOMETHING I NEVER ASKED OUTLOUD!

Thank you so much! I may not be able to explain like you if anyone ask me why DOHC is better because I'm very bad at math but It's not really hard to see that in DOHC there's more area to intake and exhaust! And I just learned what means *lift* of valves ^^ great video 👍

What about 5 valves like in my Audi?

@tobmaster1985

8 жыл бұрын

yes, a video about the 5valve DOHC engines (1.8T 20V, V6 30V, etc) from Audi would be great

@luislaurencio

8 жыл бұрын

+Kanice 3 small valve intake , 2 big valves exhaust

@MrNicholg

8 жыл бұрын

+Kanice same principal, but starts to diminish in returns due to weight.

@EngineeringExplained

8 жыл бұрын

You have the tools! Now you can math out a 5 valve. :)

@miagi1337

8 жыл бұрын

+Kanice 5 Valves give the optimum air flow. But it shares a problem with the 2 valve system. Where to put the spark plug and injector. Actually compared to the 2 valve system, a 5 valve intake leaves pretty much no space for spark plug and injector. And the positions of both can make an important impact on the combustion, regarding torque, efficiency and emissions! Btw in engine development, the small bits of material between the valve opening marked green, are quite and important point. That bit of material has to withstand high mechanical and thermal stress and may never break or fail. Having more material there is also an important advantage of a 4 valve intake.

why are rotary engines not very popular?

@EngineeringExplained

8 жыл бұрын

I'll have an answer for ya very soon! (In video form).

@gideonsimiyu2668

8 жыл бұрын

Thanks that's very considerate of you.

@EngineeringExplained

8 жыл бұрын

Gideon Simiyu Haha well I had a 13B in a few weeks ago, and made a video on the topic. :)

@gideonsimiyu2668

8 жыл бұрын

+Engineering Explained I have no idea what a 13B is, but I have a general knowledge of how rotary engines work.

@louiegonzales2574

8 жыл бұрын

Leak

great video illustration, thanks mate...

The 12 valve cummins was weaker than the 24 valve. Thank you video cleared up a lot.

So then why does like Chevy still use 2 valves per cylinder?

@bahamatodd

8 жыл бұрын

+RyanRC2 The engine only has one cam shaft. It is a simpler design with less parts that can be packaged in a smaller overall package. The US also doesn't have displacement and CO2 emissions taxes so they are free to use more displacement to make up for it.

@bahamatodd

8 жыл бұрын

+Petar Bogdanov They use the OHV design to reduce cost, size and weight. To make up for the deficiency in the 2V design they need larger displacement to make enough power. The larger displacement is a result of the OHV design, not the other way around.

@gigagdragoon2345

8 жыл бұрын

Chevy uses 2 pushrod 2 valve per cylinder v8s with a single camshaft that drive all of the valves. The advantage is that they can make their power requirements, for example 450 hp @6000 rpm with an engine that weighs less, makes more torque, has less moving parts, doesn't have to rev as high to make the horsepower, is physically smaller and has a lower center of gravity than a naturally aspirated dohc v8 engine that makes 450 hp @ > 8000 rpm. So ideally you can accelerate faster, corner better, brake harder and later. This chart shows you that the pushrod v8 has a better power to weight ratio than the production dohc v8s. imgur.com/kUyUXSC

@bahamatodd

8 жыл бұрын

+Petar Bogdanov You make the engine as large or small as you need to. Horsepower is calculated from rpm and torque. Want more power? Increase either of the two. If you have restrictions on displacement and emissions, you're forced to lower displacement and higher rpms (or forced induction) which requires a better breathing more complex DOHC design. No restrictions? A higher displacement, simpler OHV design is much more economical.

@250lmferrari

8 жыл бұрын

+RyanRC2 don't listen to Todd yes it's cheaper and simpler but compare it to the competition. if you look at for example the Audi R8 vs the c7 corvette they make similar power, both v8's the Audi a 5.2L DOHC motor the corvette 6.2L OHV but the covette get better fuel economy not only by the EPA but also in independent authentication

More mechanical parts = more problems

@jamestupper5599

7 жыл бұрын

MRios1128 More power = more fun

@dudeshark2471

6 жыл бұрын

That’s not true at all

@MrCrackbear

6 жыл бұрын

then why not ride a bike?

@mohammedsalimahmed5230

6 жыл бұрын

Dude Shark generally speaking it's actually quite logical to think like that. So what you're saying is more mechanical parts = more reliable? More mechanical parts means more *potential* problems. Either way I just want more HP.

@dudeshark2471

6 жыл бұрын

Salim Ahmed I mean technically yes less parts means less POSSIBLE problems but that’s only under extreme circumstance and design is what matters. Because if you think about it, the rotary engine is less parts that any conventional engine and is known for it’s unreliability

If you could do a video explaining why two valves make more power and torque at low revs than four due to gas speed I'd be grateful. Explaining how valve seat curtain area as above is great for high revs but the other side of the story is well worth telling also. great vid though and thanks for doing it.

Your videos are absolutely great. Keep it up

For the life of me, I fail to understand how or why this topic is still being debated. Well, unless you're from North America where, with few exceptions, 2 valves operated by pushrods are still the norm. I expect people will reply saying that a big block Chevy (or similar) can make 800 hp easily and yes it can, if you use a big cam, outrageous ports, very high compression, etc. all for overcoming its inherent badly designed heads. This applies to almost all North American engines, even the Chrysler Hemi. Even North American motorcycles (with few exceptions like the H-D V-Rod) are stuck in the early 20th century and struggle to make 0.75 hp per ci when a DOHC, 4 valve engine can easily make 2.5 hp per ci in a state of tune that makes it very rideable on the street. Then, people (Americans) will say that those little Japanese buzz-boxes don't make near the power of an American V-8. That's because they're little. American V-8s (and V-twin bikes) make the power they do purely because of their size, nothing else. Now, before the hate mail starts, let me say that I have a Ford with a 460 in it, which I love but I see it for what it is - a motor that puts out only half the power it should and puts out what it does only because it's so big. I'm also building a hot rod with a 383 Clevor and CHI 3V heads. I also see that for what it is - a medium sized V-8 with aftermarket heads that are as good as a pushrod operated, 2-valve head can be. I dig Fords and was overjoyed when they finally let go of their 2-valve, pushrod engines. That said, at almost the same physical size as the old 427 SOHC, the Coyote is far too big physically for its capacity. I've seen comparisons between it and a Chevy LS on Engine Masters and the Chevy makes more power, as would a Dodge Hellcat but they always say the Ford puts out way more power per ci. If power was the objective, Ford could've beaten all others if only they'd made it the same capacity as the others. If getting respectable power from less cubes was the objective, they've done pretty well but I wonder if that was their objective. In closing, if anyone wants to argue a case for 2-valve engines (operated by anything other than DOHC) then they should also argue a case for valves over transistors in electronics, pistons over turbines in aircraft, steam over diesel in railroads, etc. Oh, and imperial measurements over metric.

@amineboukraa

7 жыл бұрын

God damn right!

@charliebomps6564

7 жыл бұрын

OHV engines have many advantages over DOHC engines including compact design,less moving parts,higer torque,lower weight,simpler design(though still complex),lower center of gravity,and much cheaper to hop up.Anyone who makes a case for why we should use DOHC engines over OHV should also make the case for why we should use steam over gasoline engines,why we should use coal to power trains,why we should use tube televisions,why we should use arrows instead of guns,etc.

@charliebomps6564

7 жыл бұрын

David Rayner Making the engine bay larger to fit a larger but equally powered engine is ricer logic.If you make the engine bay larger then you would also use a larger OHV engine and you would still make more power than DOHC.On DOHC you also tend to gain primary and secondary chain tensioners and cam followers.OHV produces higher torque because if it is the same physical dimensions as a DOHC engine it will have more cubes/liters.An aluminum OHV engine will still weigh far less than an aluminum DOHC engine.Complexity is bad because it increases the amount of things that can go bad.A lower center of gravity is extremely important in cars because it will give much better handling and is exactly why sports cars use OHV engines.That was a extremely poor argument made by you on increasing engine power because if I have an OHV engine with 1 camshaft and less complexity it will always cost less to make hp than a DOHC with multiple camshafts that you have to deal with .I stated those arguments you should make because the OHV engine was invented after the OHC engine and you are the one who want's to use the older technology.

@davidrayner9832

7 жыл бұрын

Before I start, this may be lengthy and I had this debate on another post and someone complained that I should've used paragraphs. I did, but when I hit "reply" it made it all one paragraph and I don't know why. If it does that now, please try to read it all anyway.Ricer logic? I gather that means Japanese. When an OHV engine makes say, 1hp/ci and a DOHC of the same capacity and in the same state of tune makes almost twice that, yes the DOHC engine is physically larger but how are they equally powered when one is making way more power than the other? Of course an OHV engine will weigh less than a DOHC engine if they're both made of aluminium but since most American V-8s are cast iron then weight is obviously not a concern. If a company now makes a cast iron OHV engine and they want to make a DOHC engine but its weight is a worry, then they can make it out of aluminium. Problem solved. If the OHV engine and the DOHC engine were the same physical size but the OHV engine has more cubes because they can fit into the available space not taken up by those huge DOHC heads, then one is making its output by virtue of its capacity (like my 460 Ford does) while the other makes its output by virtue of greater efficiency from less cubes. Both are good ways of making power but what I'm saying is that if you want to make more power, there are ways of doing it besides simply making the engine's capacity bigger. More cubes isn't always the only answer. You may have gathered that I'm into bikes just as much as cars. Using my example of the Sportster v the Suzuki TLR, what capacity would the H-D have to have and how physically large would it be to make the power of the TLR but in the same state of tune it is now? Answer; so large it wouldn't fit in the bike and both of us together couldn't kick-start it. As for complexity, I own a pushrod engined van right now and it runs like a Swiss clock but so did the 4-valve SOHC cars I've owned as do the three 2-valve SOHC bikes I have and the 4-valve DOHC bikes I used to have. They were all as reliable as each other. I even owned a bike with only one cylinder but with 4 radially-disposed valves which needed 8 rocker arms to actuate. Guess what, it never missed a beat. I agree a low centre of gravity is important in cars, especially sports cars but Ferrari, Lamborghini, Maserati, Mercedes Benz, BMW, and Jaguar (with their complex V-12s), would not dream of making a 2-valve pushrod engine to get a lower C of G. Notice there ware no ricers in that lot. BTW, which (true) sports cars use OHV engines? Oh, the Dodge Viper and the Chevy Corvette. Both great cars and I won't hold their engines against them. I'd love to own either one. Actually both but I'm not made of money. I'd rather a Lamborghini Diablo though and if I ever got to drive one, I doubt I'd find it unstable because of its engine.As for the cost of increasing the output of the pushrod v the DOHC, of course the DOHC will cost more but why would you want to when it makes more power than the OHV engine ever will in a street-able state of tune? Did you miss the part about the Sportster v the Suzuki TLR? If you spent a certain amount on the H-D and then the same, no, more on the TLR because it's more complex, the TLR would be a missile. There are pros and cons to every design and DOHC has its cons but the output they give is worth it, it most cases. Pushrod engines have their advantages but to get the output of a DOHC engine of the same size, the pushrod engine will be in a state of tune which makes it no longer usable on the street unless you like to impress people with the fact that it won't idle, overheats in traffic, and won't run well under 5,000 rpm. In a race car, that's fine but I have no wish to drive something like that on the street. Ah, then why am I using a Clevor in my rod, you ask? Because it must be 1970s period correct. For the same reason, I'm using a beam front axle on a transverse leaf spring when IFS is far better. I'm sacrificing superior technology in favour of looks purely because it's a '70s era rod. As for the OHC engine pre-dating the pushrod engine, that may well be but even if the pushrod engine is newer chronologically, it's still a backward step in engine evolution. The point of this video was to illustrate that a 4-valve engine can move way more air than a 2-valve engine (with no mention of how many cams or where they are located so we'll go with the most obvious but then again, the 2-valver could be a Jaguar inline 6 which is a DOHC 2-valve) and he says to make the 2-valver move as much air as the 4-valver, it must have its valves open further (or for longer, or both). There's your big cam, your lumpy idle, and it just goes on and on from there. This video didn't tell me anything I didn't already know. It wasn't meant to convince me, it was meant to convince you so rather than debate the topic with me, why don't you debate it with the person who made the video? Tell him that the disadvantages of a 4-valve (and presumably DOHC) engine don't come close to making up for the extra power they give. Let's see what he says.

@bcubed72

7 жыл бұрын

1) 2 valve is cheaper, so you can afford a bigger engine. The 4-valve DOHC wins the "HP per cc" race, while the OHV wins the "HP per dollar" race, which is the important one. 2) 2 valve is better at low-to-mid RPMs, where the typical motorist spends 90+% of their time. Actually, many "4 valve" designs deliberately DROP a pair of intakes (on the "slow" cam) to keep intake VELOCITY up, which improves midrange. (EE didn't really get into that, which disappointed me.) 3) Maintenance is less on a 2 valve engine, vs 4-valve, and (particularly) on OHV vs OHC. If you OWN the vehicle (vs merely race it), that's important. 4) Torque! Torque is more important than HP to a non-racing grocery-getter, because you spend far more time around the torque peak, than you do around the RPM peak. 4 valve engines lose midrange (as specified above), unless you add some sort of VTEC system (which is the best of both worlds, but ups purchase cost and maintenance.)

An additional advantage that 2 intake valves offer over a single is more turbulent air flow in the cylinder. This is essential for fuel mixing and increasing the burn speed/efficiency.

i like this a lot and add my humble name to the subs list ! One question, why isnt everyone using this 4 valve config, and what are the advantages apart from the one shown? or maybe there's another video showing this already :)

Thanks your description are complete!

Great video. Thanks for sharing 👍

Subscribed. You are the best 👍🏻

Damn this really showed me more than I learned in class, the video:true explanation of the difference. Class: there are some engines with dual valve, 4 valve, and some 5 valve engines but mainly 4 and 2 valve

easy to understand , ty bro.

4 valves, this is an awesome way of bringing the teaching. I like the marker board but this is the best

Really like the powerpointesque presentation.

new format is awesome

Thank you so much

Something else that wasn't touched on is at low lifts you get more air velocity which promotes low end torque. You can open a DOHC valve less to achieve the same flow but you'll have increased velocity at the same airflow. Having to open the valve more on the 2 valve to achieve the same airflow kills velocity and thus torque.

Awesome explanation. Thanks!

I know it will depend on the stroke ratio, but at what rpm would you start to see much of a difference between the maximum sized 2-valve and 4-valve configurations? I would guess about 3500 rpm. Is there a general formula for flow-work across poppet valves? I expect the flow could be fairly turbulent (swirly) and difficult to analyze.

wow love the breakdown

Very interesting video Enriching - tests and opinions

love this new method ;) seems to work better with more complicated lessons

Excellent explanation!

The thing about a OHV setup though, is that you can place the engine much lower due to less area being taken up compared to the bulky cam setup on a DOHC engine. Not that it makes a huge difference in performance, but it is somewhat beneficial.

Holy Crap this is the stuff I use in school add that with my love of cars and this video gets a thumbs up from me.

Very good explanations! Great experiences. Thank you for Sharing!

great video cheers

You left out one of the other great advantages - weight . Smaller, lighter valves start and stop easier and allow lighter springs and higher revving.

@EngineeringExplained

8 жыл бұрын

+scanspeak00 Yep, light valves help prevent valve float thus making it easier to reach higher RPM.

@danielwarren6845

8 жыл бұрын

+Engineering Explained so how long till we see 6 or 8 valves. Or has that been done already.

@joscythe556

8 жыл бұрын

+Daniel Warren There are are engines with 5 valves per cylinder to my knowledge

@scanspeak00

8 жыл бұрын

Joel Sägesser Yes some Ferraris have that.

Mine Opel corsa B had 8 valve and mono injection. And many mechanics told me that 16 valve version of same corsa much more troubler than mine. A simle prevails!

thanks alot really helped with my project

Good video. I suppose you might have a tad more issue with inertia to balance from the OHV piston rods if there was greater valve lift, too.

As always i enjoy and learn from your posts. Would you consider educating some on how OVER-SIZED wheels affect braking and rolling inertia on brake system and bearing etc.

Jason, you're the GOTO guy because you explain auto mechanical engineering better than most. That said, my question (however ignorant since I'm only learning), is not exactly related to this topic. I've had a few performance upgrades to my car which is a DOHC I-4 GDI engine. Although I've not yet experienced any backfire, I'm concerned that I might when I run it up to 7,000 Rpm. QUESTION: Should I consider advancing the timing a couple of degrees toward Tap Dead Center when I change the spark plugs?

1 spelling mistake between greater intake/exaust percentages all in all great as always

Really nice explanation.

WoW , awesome Vid , Thanks Very Much ;]

This video is good, but I really enjoy the explanations on the board better. ...I always hated when my professors gave classes with powerpoint, and this reminds me of that.

what a great short video!

Well done white-boarding here. good job!

Thank you Jason. Got it.

Very good and well explained video!

All of your info is spot on, but the use of the term"area" for the actual "volume" rendered when the 30mm valves are at full lift, unnecessarily confusing given that area is coincidentally the term used to describe the two dimensional "pie x diameter". Just thought I would mention this since others are probably thinking it.

@EngineeringExplained

8 жыл бұрын

Pi*D is the circumference, thus just one dimension. Or am I still missing something?

3rd! Once again bro your very smart. You break everything down and tell it how it is.

my inner math geek is tingling great video