Multi Valve Per Cylinder: 2V, 4V, 5V, 6V & 7V

The need for more valves per cylinder was quickly found in race cars when first manufacturers found out that it can significantly boost the output of their engines. The first 4V engine basically came over a decade ago and became the standard in road cars not a long time after that. The progress did not stop there and more valves were tested for any possible further power improvements, especially by Maserati, Audi and Yamaha.
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[@robinsage1964]

Would love to see a video on the Honda oval piston engine.

[@theGabe87]

Visio made one

[@maya00795]

Honda nr750 🤩🤩🤩🤩🤩🙏🙏

[@jkim6200]

@@maya00795 nr500 gp machine actually preceded it.

[@jkim6200]

@Alfred Wedmore More than that, Honda was insistent on taking on the GP competition with 4 stroke technonology upon its return. 2 strokes had been dominant since the mid 1970s, and this quixotic quest was further complicated by the restriction on the number of cylinders (which you alluded to in your comment). Honda came to its senses and abandoned the NR for the time being and introduced its own 2t NS500, albeit as a v3 and not a v4.

[@rusack7174]

@Alfred Wedmore I didn't think so. Yes, they wanted to race more than 4 cylinders so this was their way of keeping 4 cylinders (although unconventional) but pushing through the airflow, thus more power, they were looking for. I thought a very fascinating engine thought very complex.

[@rolanddutton4723]

Brilliant video. It's impressive how far this channel has come since I first tuned in.

[@VisioRacer]

Thank you, Roland, I appreciate it very much

[@LandonClimbs]

Same. Been a follower since maybe 2016? Definitely 17

[@Errol.C-nz]

@@VisioRacer still not quite there.. valve .. area equate to port section area & port flow .. there is a measure affecting port bowl & throat flow.. valve perimeter opening area.. for the same valve "head" area.. the valve head perimeter area is measurably more as more valves are used.. giving a faster effective opening.. on top of the more smaller valves can be opened more rapidly for the same engine/cam rpm's.. piston speed is the most limiting factor for engine rpm more so than valve bounce & valve train mechanical resistances

[@Errol.C-nz]

@@VisioRacer your channel does good work, but.. conclusions & reasons for the concepts fruition are misleading.. research into Norton's 2 valve Manx 500 & discover volumetric efficiency multivalve engines can't achieve with effects on diffusing pulse wave energy of pulse tuning exhaust systems.. as with misconceptions of valve "area" .. vs port area .. without consider the valve seat curtain area at the critical choke point of ports .. the valve/port seat opening area 5 valves have over 4 .. effects of 3 inlets doesn't translate across to benefit exhaust valve flow either .. all critical key points missed.. 4-valve design does benefit from being more "tunable" from any base point variation.. but 5 valves have better ultimate potential as a design stand point.

[@KingBanter]

The sound of the Ferrari from around 3:41 is un believable !!! Great video as always VisioRacer! Cheers 🍻

[@apancher]

The banshee scream of a 355 is one of my favorites!

[@KingBanter]

@@apancher it’s unreal!!! That’s the first time I’ve heard it on board . Savage machine

[@KingBanter]

@@apancher would you say that is the sound of a stock 355 F1 or has it been modified?

[@trianifeA7x]

@@KingBanter stock they sound good, but not nearly as loud as in the video, sounded really loud and hes on the track so probably no muffler or cats.

[@KingBanter]

@@trianifeA7x yeah I’d say you’re right! I was a passenger in a 458 once and it sounded amazing , but the one in this video is on another level😻

[@JohnCompton1]

Never thought I would enjoy a channel specializing on the diversity of internal combustion engines until KZbin algorithms was kind enough to drop this gem in my feed. The topics are always interesting and very well presented.

[@VisioRacer]

That is pleasing to hear, John, thank you

[@aaronburratwood.6957]

I know the coyote engines are amazing but I’ve had two aluminum four valve 4.6 litre cars and they felt great but sounded amazing from idle to redline. Another great video, five valves was the most I’d heard of before this. 🔥

[@pvrrpghxst7867]

I had a 2v and a 3v 4.6 both Mustangs and I think the 3v sounds the best off all 3 4.6 modular engines

[@wades623]

I've only heard of 5 valve too since I have one

[@chehystpewpur4754]

@@pvrrpghxst7867 you got a ford to run long enough to hear it? lucky dude.

[@aaronburratwood.6957]

@@chehystpewpur4754 It doesn’t happen much but when it does ya better get out the way or hold on tight depending on where you’re at.

[@aaronburratwood.6957]

I had a ‘96 Cobra & an ‘03 Mach1. I miss them both but I’m building something better now.

[@M.L.R.Z.]

I've had the Audi s6 with 4.2L V8 5v, it was an absolute dream to hear the car on a cold start and to drive it

[@mikehotchkiss8975]

500k looming. Another great vid, thanks

[@VisioRacer]

Thank you, Mike!

[@Dr_Reason]

A short stroke 5 valve requires a larger dome for compression, at some point this make the combustion chamber just the collection of the 5 cylindrical valve clearance pockets and this requires huge ignition lead. Yamaha race bikes ended up with 46 degree BTDC timing and this lead to the engine losing torque. Basically they could run high compression for midrange pull or they could open up the combustion chamber and get good combustion near redline. This meant that the competition 4-valve engine either had an advantage coming off the corner or at the end of a long straight; choose your poison. That was the end of racing 5 valve motorcycles. It does work better on the street as fuel quality limits the compression ratio and that allows the lower compression to be effective in the midrange since the 4 valve cannot raise the compression any higher due to fuel quality. Fuel quality really effects engine design. PS. Talk about the 3-valve engine. I like the Ford V8 and V10 truck motors.

[@ArneChristianRosenfeldt]

F1 engines have rocker arms and radial valves. With one rocker arm in reverse direction to the camshaft ( like in VR6 ), you could have a radial-5 valve arrangement. Then reduce the dome in the head and keep the piston flat until compression is correct.

[@loganamurray64]

You actually like the 3v Tritons? Just about the most problematic engines money can buy

[@Dr_Reason]

@@loganamurray64 Not near as bad as a 4100 Cadillac.... But you are not wrong. I like the way they run, especially in a truck. Great mid range torque and decent horsepower. Too bad about the spark plugs and....

[@isaacsrandomvideos667]

No clue what you’re saying but it seems intellectual and interesting so I totally wholeheartedly agree

[@georgebarnes8163]

You can always put the combustion dome in the piston and use a flat head.

[@Eunos13RE]

I always considered your channel as real great and professional... but this, this comes to a different level honestly. Truly it's a masterpiece of a video.

[@isakjohansson7134]

Rotary valves could be an interesting topic to cover at some point. Awesome video!

[@streetter666]

Thank you! Good video!

[@VisioRacer]

Thank you too!

[@arnaldorentes5371]

I have a hunch this is the best video you've ever made. And about the evolution of your work, the advance is remarkable. Sincere congratulations!

[@VisioRacer]

Thank you, Arnaldo, very much! It means a lot to me!

[@Tom-Lahaye]

There was / is a mass produced 6 valve per cylinder engine, however it's not a car or motorcycle engine but a large diesel used in ships, locomotives and gensets. It's the Maybach MD series and its MTU siblings still built to this day. Well known amongst diesel locomotive enthusiasts are the MD650, MD655 and MD870 used in some German (V80, first ten V160 and first ten V200) and British (Warship, Hymek and Western classes) locomotives. But also used on exports to the US, Thailand and Indonesia to name a few. The engines have 2 camshafts, one for the intake valves and the other for the exhaust valves, the middle valve of the sets of 3 uses a bit shorter rocker arm than the other 2. One of the camshafts also operates the direct injection pump/atomizer units which are fitted to each cylinder. The Maybach uses no conventional diesel pump but it's the system alter advertised by Volkswagen for their "pumpdüsen" car engines, only the Maybach used this system 50 years before VW did!

[@mariozetik]

Hi Tom, these engines are not direct injected, using unit injectors like newer MB 500 truck engines or VW TDI PD engines later, but they have indirect injection through pressure chamber (unlike Ricardo comet swirl chamber, that was typical for Mercedes-Benz prechamber diesels).

[@kotelypiesely1268]

1.8T babey!!! finally!!!

[@EricMuller]

I hadn't heard of 4 valve flat heads before, that was interesting. A video on flatheads might be fun

[@michaelmurphy6869]

Another fantastic video!! Thank you VisioRacer!! Always learn something new. Cheers my friend!!

[@robertpierce1981]

3:41 damn that sounds good!!

[@dannylopezcalderon7825]

Amazing video!!!!!

[@dukiemoto8676]

Another great video👍🏼

[@shitvalancheofdivercity14-.-88]

I have the renowned 1.8T 20 valve engine in my VW Passat 4 motion with 5 speed manual transmission. My engine code AWM. It's all OE with 116k miles. I replaced the head gasket at 111k miles and got a first hand look at the 5 valve per cylinder head design as well as the variable valve timing which is ran off the back of the engine via a chain and a oil pressure controlled chain tensioner. When I bought my car I didn't know there was as big of a cult following for this engine as there is but I'm glad because it gives me peace of mind knowing how reliable it is. For those curious, the head gasket failed when the last owner didn't purge all the air out of the coolant lines after hitting something and having to refill the system and therefor the coolant couldn't reach the sensor to display the temperature, it oddly always ran a little cool because the sensor was only barely getting wet, resulting in a blown head gasket. I repaired it myself in my driveway with mostly hand tools. And no, I didn't have to have the head machined.

[@CarputingYT]

Wow, now this is a great topic! Thanks VisioRacer, for another awesome video. Keep doing what you do bud! Have a great day.

[@VisioRacer]

Thanks, mate!

[@Manoah.]

After seeing this video, I love my Audi A4 B5 1.8 20V turbo even more :)

[@valiantdiesel1332]

The professionalism and effort put into this channel has increased so much since I first subbed AGES ago, can't thank you enough for the interesting content you bring us petrolheads on such a frequent basis!

[@VisioRacer]

Morgan, to be honest I can't express how grateful I am for comments like yours. They drive me forward, thank a lot, mate!

[@andyharman3022]

VisioRacer covers it all. Here's one to consider: double-acting two-strokes.

[@mainlander6299]

Excellent video 👍

[@actuallyusingmyrealnameher5061]

3 valves were used in many cars too, two small inlet and one larger exhaust 🙂

[@chrisbort6083]

My honda vt600cd has a 3 valve setup 🙂 revs to 8000 no problem

[@TheSilviu8x]

@@chrisbort6083 mine is a two valves and goes to 11500rpm. It's not a rev limiting factor, but it's for the overall/maximum power. Two valves on small engines gives stupid high fuel economy tho...

[@TheSleepyMechanic0524]

@@TheSilviu8x I got 120 miles on a 1 gallon tank with my go cart. You're not wrong lol

[@thepurdychannel8866]

@@TheSilviu8x my tdi is 2 valve per cylinder 6 valve total

[@The-Rectifier]

Indeed toyota used them back in the days a lot, in several models

[@ScienceManiacCZ]

Great video and you're 100% right in that smaller valves mean less weight so it gets to rev higher. However it does not increase flow, it increases velocity. Technically it impedes flow because there are more obstacles between port entry and combustion chamber entry. The tiny bit of flow you loose is offset by the amount of port velocity during scavenging when both intake and exhaust valves are open making an incredibly turbulent air/fuel charge while being able to rev to the moon. I love multi valve heads, always drooled over the ohc hemi concept from the 60's

[@BigUriel]

The main variable is air passage area. The area is ultimately given by the imaginary surface of the cylinder that goes from the rim of the open valve to its seat when open. The more air flow you want the greater this variable needs to be because you can't simply force air to move faster and faster, when it reaches the speed of sound you create a choke point and it won't flow in any faster. The simplest way to do this is more valve lift (increase the height of the air passage cylinder), and that's how it always used to be done and is still done nowadays as a modification for high performance engines (that's what racing cams are), but since the 60s/70s the compression ratio of road engines increased a lot and that limits how much valve lift you can get away with before your pistons are hitting the valves. You can also only fit valves so big before your run out of cylinder head surface (without having to keep making the engine more oversquare which also has disadvantages), ergo more valves - you have more total valve perimeter with two small valves than one big one, for a given available head surface. From 3 to 4 valves there is a considerable increase in this area, from 4 to 5 a very small one, from 5 to 6 next to none and the extra valve stems in the way actually start to create a choke point of their own.

[@theGabe87]

Do a list of engines that were designed for motorcycles but ended up in cars. And vice versa

[@hank1556]

BMW K100

[@theGabe87]

@@hank1556 is that int the i3 Rex?

[@Ari-pw6nu]

Nope. MC=lightweight. Car/truck=heavyweight. MC=tight, performance tolerance. Car/truck =loose, reliable tolerance.

[@theGabe87]

@@Ari-pw6nu for example iirc the honda n600 kei cars were made with engines developed for MCs and so does some Fiats. Edit: Honda N360.

[@paulg3336]

The Peugeot diagram shows a desmodromic system with valve springs. It is common to use low tension springs in desmodromic systems to ensure the valves fully close. Ducati has always used springs in their desmodromic systems.

[@rdaw33]

Talked with a Ducati tech person at a race, was impressed with the desmodromic system. They had an actual production head to handle!!......they used a valve spring so weak that you could open the valve very easily with your hand. It was explained that the spring was only needed to aid easy starting. Normal running did not require any spring as compression would make the valves properly seal when running.

[@graemescott1436]

Iconic Mazda engines or have you done that i forget seem them all tho man keep them coming

[@waynes.2983]

Machining those oval piston engines must have been quite a task.

[@philiptownsend4026]

@@greatestevar but surely the same is true of ovals as they have two half circles. Actually the perfect anything doesn't exist but the closer to perfection anything will be superior, if worth it in the application.

[@seth094978]

@@greatestevar That is false on several levels. Circles, even overlapping ones, are typically going to be par easier to get precise. Anything with flat sides and circular features is going to be much harder, though I will admit that with modern high precision cnc machines I don't think it would be too too difficult to make the block and pistons of that engine anymore. Honing would be significantly more difficult, and I have no idea how the rings could be made.

[@carsbikes4520]

Man... u have best videos... just keep going!

[@VisioRacer]

Thank you!

[@Aaron-be2pt]

Hey Visio man, I hope you're going to school for automotive engineering or some kind of engineering because you really seem to have a love for the field. I always enjoy your videos!

[@VisioRacer]

Thank you, Aaron!

[@BuddWolf]

Thank you for the educational and entertaining video post. I always enjoy your vids young man. I remember the oval piston Honda in the early 1980’s. I read the article about it in Cycle World magazine and was amazed by the ingenuity and chutzpah by Honda to try such a rad design. Thanks again Best of luck 🍀👍🏼to you and your family

[@martinz.4802]

I love your videos🙌🏼❤️!!!

[@niklasschmitt]

That was very interessting! Thanks for the work you put in the video :)

[@VisioRacer]

I apreciate it, Niklas!

[@jonntischnabel]

Used to have a 30v Audi 2.8, what a lovely engine it was.

[@aditya-br3kg]

nice vid, thx you so much for that information

[@connieschmitt714]

I am glad you have new videos please keep them coming!

[@VisioRacer]

I started posting more story-like videos about automotive topics. Glad you enjoy them, I do a lot!

[@misters2837]

As Always your videos are quite informative..

[@maya00795]

Thank you dude 🤩🤩🤩🤩🤩 awesome 🙏🙏🤠❤️❤️❤️❤️❤️❤️❤️❤️😘😘🙏

[@tymac3306]

and yet he did it again,....a new topic..keep it up!

[@wilbur9416]

Always interesting videos, keep it up

[@masterSe7en77]

I love how informational ask your videos are and I appreciate all the hard work you put in to do so

[@VisioRacer]

I appreciate that!

[@Ragna-Rok1]

I would love to see a video of snowmobile engines!!

[@grahamnutt8958]

Excellent content as always VR. You asked for a suggestion ref: topics to explore...... I know virtually nothing about a relatively rare phenomenon that, if memory serves, was explored by Alfa Romeo..... Twin-Spark (was it the AR 33?).... A video from you covering this subject would be appreciated. Huge respect for the content 👍

[@actuallyusingmyrealnameher5061]

Two other cars using twin spark plugs, Porsche and Smart with the 450 🙂

[@grahamnutt8958]

@@actuallyusingmyrealnameher5061 TY for the reply. Hopefully gives our host something to work with and research. I was unaware of anyone other than Alfa that had looked into this. Respect 👍

[@VisioRacer]

I know a few more: there was one or more Mercedes engines and the 13B engine although that is not a piston engine, of course.

[@grahamnutt8958]

@@VisioRacer 13B.... Mazda rotary? You can have a field day with this one, pal. Respect 👊👍

[@rednecksnredlines]

@@actuallyusingmyrealnameher5061 Ford Rangers with the 2.3 Lima had twinspark setups. So do new Chrysler Hemis.

[@paulg3336]

There is a benefit to more valves that you did not mention and it is one most people don't think of. More valves gives a greater total valve circumference. This effects gas flow when the valves are partially open ,as they are during most of the cam lift rotation. If you show a graph of the increase of flow as the valves open, the engine with more valves has a steeper curve. This is equivalent to having a really aggressive cam profile ,but without the mechanical problems such a profile would create.

[@cwt5654]

Remember there is flow restriction between adjacent inlet valves but good comment...

[@Jacob-W-5570]

nice video! (although I secretly love the one valve engiens best)

[@cwt5654]

Yes... only problem is where to put the spark plug! :)

[@Jacob-W-5570]

@@cwt5654 Diesel

[@cwt5654]

@Alfred Wedmore These are 2-stroke engines - poppet valve is exhaust only. A true monovalve uses single valve for both induction and exhaust.

[@cwt5654]

@@Jacob-W-5570 Indeed.. the manufactured examples were side-valve (flat head) type but OHV version was planned. Would have been interesting!

[@cwt5654]

@Alfred Wedmore If you assume a 400cc cylinder (75*90mm) with flat head surface using piston bowl combustion chamber and mono valve flush with head face, the bowl would need to be 40cc to reach a compression ratio of 10::1. Assume valve is 45mm diameter, a 50mm diameter bowl would allow a 20mm travel before contact (according to my calculations). For a spark ignition engine this is plenty of clearance but even with compression ignition (15:1) there could be up to 13mm travel. Few engines of normal capacity exceed this amount of valve travel. With regard to restricted breathing, unidirectional valves (reed or flap type) can be fitted allowing separation of incoming and exhaust gases in the chamber preceding the monovalve - exhaust control valve could have heat issues!!

[@caty863]

I always thought the engeneers increased the number of valves only to improve breathing. It's good to know it allows higher redlines too. I selected my 200cc motorbike simply bcs it had 4valves over its competition which had only 2. I'm now proud of my choice and I will be able to explain it better to my friends when they ask me again the question: "why bother?"

[@JazzbLu]

We did love watching it! Thank you so much!

[@wernerschulte6245]

Again thumbs up ! Having pretty much knowledge about engines I get new information to think about. It is clear and easy to understand. However I never thought about advantages for lighter valves concerning maximum engine speed

[@TeslaHaxz]

Glad to see the mitsubishi 5 valve mentioned here

[@alves89]

And congrats, your videos enjoy me so much

[@TheAussief1]

I remember reading about this in a book, printed in the 30’s.

[@manuelvpr]

Great engine makers know that the 4 valve is the evolution of the 5 valve engine.

[@Bryan25105]

Woow that some proper valve settings

[@contomc]

My 2006 Audi S4 4.2L V8 has five valves per cylinder, interesting to finally hear the reason why Audi switched to four valves per cylinder in the 4.2 RS4 when the rest of the engine geometry is very similar; with the introduction of direct injection they needed more space

[@jangkar-laut]

very useful to add insight and knowledge

[@sportsmansparadice42]

3:40 The sound of that small 3.5 liter V8 Ferrari 355 never get old.

[@bingbong7316]

I had a Yamaha FZX750 back in 1987, Genesis engine tuned for more midrange. Stunning, loved that bike. Pity I almost died, really.

[@johnsmithfakename8422]

Great work. I already knew most of this because there was a time I was looking into engine valve technology. I can go down some unusual rabbit holes. There is new technology (FreeValve technology) that can cause a return of 5 valve per cylinder engines. With a camless design one of the most difficult aspects of having 5 valves is innately dealt with, the 3 intake valves do not have to be mechanically timed.

[@uwegunther1176]

Very informative especially the early years

[@josephsmith3373]

I love your videos! Very educational and you have a very pleasant voice.

[@theskig]

Greetings from a VW 1.8T 20V owner

[@alexjenner1108]

Thanks for the video. Many of those early Alfa Romeo and Bugatti shown in the early parts of the video didn't have 4 valves per cylinder. The Alfa Romeo 6C was 2-valves per cylinder and the Type 35 Bugatti appears to have been SOHC with 3-valves per cylinder. Same is also true in the 1930s, 40s and 50s with the famous Alfa Romeo 158/159 GP cars having 2-valves per cylinder at quite a large angle to each other. This was very common for DOHC racing engines of the 1950s/60s to have 2 valves per cylinder. For the 1960s Alfa Romeo DOHC engine in TZ1, TZ2 and GTA, they were twin plug, but just 2 valves per cylinder. Same with almost every air-cooled production and racing Porsche, including 908 and 917 and most likely the only exceptions were a small number of air-cooled race engines with water cooled heads. The first 3.0L Ferrari 312 F1 engines in 1966 (derived from sports car racing engines) also appeared to be using 2-valves per cylinder and 3-valve and 4-valve versions came later.

[@maxjakobsen5526]

How the hell can you continue to make so interesting videos. :-)

[@VisioRacer]

Passion drives me. Often it is the challenge to bring something new, different, interesting...

[@nick_dizzle]

Thank you for the knowledge and the great way you delivered it 🤘🏻

[@dno8025]

Excellent video as always.

[@VisioRacer]

Glad you enjoyed it!

[@Tombatin]

Loving my 1.8 20VT Golf, surprisingly torquey little engine :)

[@dennis-br6vr]

great reliable engines. the stuf around the engine not really.

[@Tombatin]

@@dennis-br6vr exactly xD

[@fabiomonteiro3896]

The PSA group (Peugeot-Citroen) , in 90's, had 12 Valves 4 cylinder, 3 valves per cylinder, the engine is 2.5 td 12v from Peugeot Boxer our Citroën Jumper.

[@vigneshwardr6102]

As always enjoyed your informative video. Great work 👍.

[@thestigseuropeancousin7941]

That 5 valve v8 sounds mental 🤤🤤🤤

[@sentinelcheese3420]

Speaking of valves, I'd love to see a video on Koenigsegg Free Valve setup. That engine could change the way we make power from the engines 😃

[@anthonygarcia5746]

@Alfred Wedmore free valve is not an expensive setup. Its actually a better and more simple. Instead of cams and springs. You get to electronically inject fuel to the engine thus removing all that junk. So less parts and more power. Less problems. I have a ford f150 and if they ever apply free valve they will definitely change the car game in terms of reliability. Cam phasers suck. Now please do more research and preach the word. Free valve is the next big thing

[@andyharman3022]

@Alfred Wedmore NO country can afford vehicle electrification.

[@Markle2k]

@@andyharman3022 Norway would like to have a quick word with you. We are not far off from the time when EVs will be cheaper to build and buy than ICE cars. Everybody in the developed world who has access to a ground floor dwelling has a filling station already installed in their walls.

[@andyharman3022]

@@Markle2k If you have a couple of days to charge your EV battery with a 110V cord. Or are you planning to buy two EV's so you have one to drive every day?

[@andyharman3022]

@Alfred Wedmore is there a lot of hydroelectric generation in Norway? Or Morth Sea gas and oil?

[@mastermachine869]

Brilliant Video.

[@outinthebackyard7579]

Thanks for doing this video it was a fun learning experience

[@VisioRacer]

Glad you enjoyed it!

[@welsh_viewer5913]

Very good video. Thank you.

[@alkiou3613]

Excellent video.

[@VisioRacer]

Thank you very much!

[@movinmetal2596]

Excellent video! Very informative 👍

[@misterbridger]

Three valves per cylinder engines are suspiciously absent from your video. Ducati used them in the ST3, giving good low-rev torque similar to the 2-valve ST2, not much less power than the 4-valve ST4 and good fuel economy.

[@youknowyouknowwho8847]

Nice vid tanks🤙👍👌

[@j.m.5995]

It's been shown that the 5valve is pretty much the best of all worlds

[@isaks3243]

I personally think that a 4v is the sweetspot. simple, cheap, reliable and efficient. but my 73 Volvo with its 2v is good enough.

[@Markle2k]

Geometrically, with a single central spark plug, 4 valves maximizes valve area to cylinder bore area ratio if you have zero valve angle. Direct injection, pent-roof and hemispherical head shapes could change this. And then you have practical considerations like valve seats of non-zero dimension, and the geometry of the valve actuation gear, and coolant passages.

[@Tom-wl9sx]

Great video as always 🙃

[@patrickporter6536]

You forgot 3-valve.

[@crd-nz_001]

Just to touch on the negative impact to airflow with more valves. While the curtain area increases with more valves which means peak flow can be reached with less lift, the overall flow through a smaller valve throat is less that a larger one. For example, the area of 3 valves with a throat diameter of 1in equals a single valve with a throat diameter of 1.733in. When we apply lift, the 3 valve needs only .25in to have the curtain area the same as its throat, where the 1.733in needs .433in. This situation is more complex due to valves having to be larger than their throat for sealing purposes, but hopefully is simplified enough to get the idea of ever decreasing valve size means the flow choke point (no more airflow available) is reached earlier than with larger ones. As smaller valves mechanically allow for higher rpm, what they don't allow is the airflow quantity. Yamahas conclusions were reducing valve throat size ultimately leads to less total airflow which directly limits horsepower. The cross over, or balance between flow and mechanical rpm, was found to be 5 valves.

[@Nudel-nc1cp]

Interesting. Yet somehow 1.8L 20v has more torque, better throttle response and better fuel efficiency than 16v of the same size. That might've been the reason some manufacturers used that design. I'm not sure.

[@andyharman3022]

And the effective difference between 5 and 4 valves ended up being ~4%, so barely worth the trouble.

[@JustPeasant]

YAMAHA used 5v for only '02 & '03 GP season. In '02, engine was still fed by carburetor. Addendum: there is not much info on GE* Evolution Series (A.K.A. GEVO) prime mover (railway & stationary engine) specs, so could you, or someone do a video on the topic? *Build by Wabtec Corp. since 25 February 2019

[@Jakek200]

Another valve configuration we can't forget is the 3 Valve, like Ford's "Totally Reliable" Triton 3V 5.4/4.6L engines. Also I think some Hondas from the 80s might've had 3 valves.

[@patrickporter6536]

I think(may be wrong) there was a Ferrari v12 F1 engine with 3 valves.

[@NitroTaki2002]

Yeah.....hate those 3V Ford V8s. And this is coming from a Ford guy lol

[@uhtred7860]

Yeah, Honda had some totally forgettable 3 valve models, CB 250/400 SuperDreams etc.

[@Xayuap]

different topic also the single valve per cyl found in engines like the R.E.P. Fan semi radial engine. That valve works in different heights to intake or exhaust in combination with ports in the sides and in the cylinder head. That engine was sick, it was like a multy bank VR7 Cyls. Double Fan

[@ПетрВладимирович-в7с]

Good one, cheers

[@Dr.Westside]

It always makes me laugh when people talk about overhead cam and multi valves being new technology . Overhead cam is only a few years newer than ohv pushrod .

[@xxxYYZxxx]

The highest possible airflow is achieved via two valves per cylinder with hemispherical heads.

[@dr.hugog.hackenbush9443]

4 valve hemispheric heads would like a word..

[@awjnck204]

bro back in the day you pull up rocking 10l 4 cyclinders, nowadays the boys are running 1.6l 4 cycliners.

[@breakfast7595]

I love the Genesis valve system in my Yamaha FZ1. Great design, awesome performance and reliability. Only problem is having to check valve clearances at 16k 🙄. Luckily it's the only big maintainence for a long time

[@monteiro5306]

An NR oval piston video would be awesome.👍

[@albanringuede8141]

Agree, coz 8 IS more than 7. Not happy with Honda choosing "oval" to describe it. To me it was a rectangle.

[@S50Sinner]

I feel like 6 and 7 valve setups could be useful in biiig bore marine engines.

[@gabrielecossettini2923]

For the 6 valeves per cilinder engines check out the Maybach MD870 locomotive engine. The 6 valves were used because there is enough space to fit them🤣

[@ratchawarutchannel710]

Thank you.

[@shanerorko8076]

People think the valve area increase is better. There are two valve engines making 1.7ftlbs per cubic inch. Yes valve weight is a benifit at higher RPM but engine stroke can make up for RPM. On a 4.400" bore space 400ci is about where it's at on a 4.600" bore space 500ci is a good number for a V8. V12 is okay but the crank gets a little too flexy so V8 is probably the most ideal engine. If you have a bike you're capacity restricted so 4 or 5 valves are a must.

[@ConcreteBombDeep]

Probably a dumb question but why are valves round? Could you not have just two valves per cylinder but in a half circle shape so that each cylinder would have maximum flow?