Rotary Valves Make Normal Valves Look Silly - Why Aren't We Using Them?
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- Опубликовано: 23 мар 2024
- Four stroke engines, which is what 99% of the engines on the road are, need to let air in during intake. The combustion chamber must be sealed during compression and combustion and we must let air out during the exhaust. This means that we need a system that can seal and unseal the chamber thousands of time per minute while at the same time withstanding the incredibly harsh conditions present in the combustion chamber.
And this is exactly what poppet valves do. They are great at sealing the chamber because the conical shape of the valve face fits into the conical shape of the valve seat creating a positive seal. Both the face and seat are made of hardened metals which offer impressive resistance to wear and increased temperature. As compression or combustion pressure acts on the valve head it actually pushes it harder against the countersunk seat. The greater the pressure the better the seal.
Unfortunately other than being great at sealing the chamber poppet valves realistically don’t have any other inherent advantages. From an engineering perspective we could even say they are a necessary evil that we managed to make reliable only with a lot of technological advancements. Did you know that back in the 50s and 60s one of the reasons why fuel was leaded is to protect the valve seats. The intense hammering of the valve against the seat under high temperature would cause microwelds between the two and as the valve opened again these welds would tear eventually leading to valve seat recession or failure. It is only when we started to phase out leaded fuel that valve seats began to become more reliable and longer lasting.
Valve springs are also a problem. At very high rpm the camshaft is trying to open and close the valve so fast that the spring simply can’t keep up. So instead of fully closing and opening the valve tends to float around the seat leading to a loss of power or even to contact between the valve and the piston in an interference engine. Valve float used to be such a limiting factor on engines that Ducati came up with the complex and maintenance-heavy desmodromic valve system just to get rid of the valve spring. Koengseeg came up with the extremely complex freevalve system to get rid of the camshafts.
But engineers persisted, they improved valve spring designs and materials and we got engines with valve springs that can rev to the moon. They pushed even further and invented variable valve timing and lift systems that can do almost anything that Freevalve can. And so the poppet valve stayed with us.
But the big problem that no amount of technology can ever eliminate is that poppet valves are an impediment to airflow. But we got around this too. We created clever intake manifolds with variable lengths and clever resonances to ram the air past the valve. We created forced induction in the form of super and turbochargers to stuff more air into the chamber. We created long and complicated exhaust manifolds to help suck the exhaust gas out of the chamber.
When you think about it a lot of the development of the internal combustion engine is actually an effort to work around the valve. To overcome its limiting factors. If you observe an engine you will see that the cylinder head and the intake and exhaust manifolds actually take up more space than the heart of the engine which is the engine block, where the crankshaft, pistons, and rods are. We need more space for the breathing equipment of the engine and we need it because the poppet valve makes breathing hard.
But what if there was a better way? What if we simply got rid of the valve instead of trying to constantly work around it.
Of course many engineers asked this question throughout they yerars and they did indeed come up with many alternatives. One of the more elegant and promising alternatrives is called a rotary valve
Instead of a poppet valve, valve seat, spring, retainer, rocker arm, lifter and camshaft all we have is a rotating barrel with cavities. As the barrel rotates the cavities in the barrel line up with cavities in the head to let air in and out of the engine.
There is no valve spring we need to overcome so this system does not drain the energy of the engine to operate which means more power and more efficiency. And because there is no valve spring there can never be any valve float at any rpm, achieving ridiculous rpm is much easier now.
This system is also very simple and it has much less moving parts which means a very low chance of failure and reduced engine size and weight.
So it’s better in every way than the poppet valve….ok…..where is it then? If it’s better in every way then why have we been using the poppet valve for the past 100 years and not this?
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Your videos remind me of a book which was vital in my years studying Motorsport engineering. Do you also have this book by professor Blair.?
think its a bit to late unless hydrogen fuel becomes more mainstream and easier to store ..Electric engine still has it beaten
2 strokes are the highest revving engines
Rotary valves need to borrow apex seal technology from rotary engines. Make the rotary valves easy to get to for replacement of seals and durability can be less of a concern.
..maybe rotating verticaly..
This man just makes me want weird engines in my cars.
Real
Idk about my car but I certainly want a garage full of gokarts with all sorts weird engine designs
no shit. bro single handedly convinced me to bike carb swap my daily driver. imagine running carbs in 2024. but it was worth it. so much fun
Before watching: The engine in my car is fine.
After watching: I want a bevel-drive, desmo, vr-5, contra-rotating twin crank design, two stroke diesel engine in my car.
@@workdesu when there’s a massive EMP you’ll be the only guy driving home.
I designed a rotary valve system once for a project, and the sealing was always a headache. I could never get it to last more than a few hours. Bravo to these engineers for solving these issues.
Use of a carbon type seal like used in turbo fan jet engines may have worked would be interesting to see. Cheers
Did you try apex seals on a triangular valve rotor?
@@JinKee no, I hadn't... *Runs to check his design*
Aside from using carbon/apex seals the best way to keep the sealing protected is by cooling. Just like a turbocharger, air or liquid cooling to keep temps stable for long periods of time. Air usually isn't feasible except for small applications but it's worth a shot.....
Why didn't you make the rotary valve in tapered form (pushed by a spring on one side) .. ?? .. so you don't need o ring seals ..
I don't really speak engine mechanics, but your explanation was so clear that I was usually a half step ahead of what you were going to say next! A really good presentation.
This. Very fun listen
I’m an engineer who trains apprentices, and watching guys like this help immensely with finding ways to communicate technical problems and solutions to laymen or inexperienced pupils.
I designed a dual overhead rotary valve system in 1963 using single long shafts. In 1966 I was living in France and met a guy who had designed a similar system and manufactured a custon head for a Renault Alpine engine, He raced the car that year at Le Mans. Unfortunately I was unable to accept his invitation to accompany him and his team to the 24 Hour race that year and due to returning to the states I never found out how it performed, although I believe their car finished the race. Very interesting video, thank you.
So a rotary valve Alpine raced at Le Mans in 1966?
Ford Australia had a 6 cylinder in their RND department back in the late 60's but it was decided back then at that time not reliable enough to put into production. My Dad who worked for Ford Geelong told me one of the employees bought the motor after they were done testing and put it in a clinker speed boat which sank after the pilot tried to make a turn on the lake at +11,000 RPM. They had left the heavy flywheel on the motor which refused to turn with the boat and broke through the bottom for the hull with the immense centrifugal force.
@@Shifty_Malone This might be a good subject for a mini documentary. It'd be cool to learn about.
@@Timbo_tango Sound like a scene from Laurel and Hardy, or Charlie Chaplin? The engine refused to turn with the boat😅
@@Timbo_tangoI'd say it's worth looking for and salvaging! 🌞
You can have 20 advantages for a thing, but one disadvantage can be too harsh and kills it.
Thanks for the video
In this case, that one disadvantage is trying to get Ford, GM, et al to use any technology they didn't invent. They will likely buy it, get the rights and then bury it.
Have you ever heard of physics? That's what makes this so much worse. It's just not better in any way
@@RekySaithere’s no physics in the way here, only bad timing and early stages development
@@cesarescrignoli442 I suspect you're wrong for there are torque advantages in 2 valves per cylinder against 4. So, 'breathing' less has it's advantages
You're just Pavlov into shitty cars
As a young man, many years ago, I remember ruminating over the limitations of conventional poppet valve designs. The idea of interrupted cylindrical rotary valves exactly like this occurred to me. I remember showing my sketches to an engineer friend of mine. He got very excited and enthusiastic about my idea. This was years before a quick Google search was even a thing. When we began to search patents and technical designs, I realized that my "brilliant ideas" was decades old, and literally thousands of people had come up with variations on this idea, and the issues with sealing, expansion under heat and pressure, and all the technical problems you list in this video were well understood and my idea wasn't unique or novel at all. For about three days I thought I might have stumbled upon that million dollar idea all tinkerers and want to be engineers dream of, only to realize I was at least fifty years late to the party.😂. This was an excellent video, and watching the excellent animations of the rotary valve idea was like seeing my rough sketches come to life. I hope someone is able to truly make such a drivetrain into a reliable real-world design. Seeing that BSA V-twin engine actually running and racing is delightful.
I'm 59 and when I was 15 I came up with the idea of a CVT transmission. I don't know if it had already been invented at that point. My wife actually has that kind of transmission in her Nissan Murano.
This exact same thing has happened to me many times before. I’ll have a brain blast for something revolutionary only to learn it’s existed for years or decades. The pinnacle of this habit was an idea I had for an aircraft engine that used the compressive force of fast moving air instead of impeller blades. As it happens, this is called a ram jet engine and has been around for ages. Needless to say this kind of thing doesn’t happen much anymore now that I’m older.
Edit: forgot to add that I too had an idea for a type of rotary valve in my 20’s. But it wasn’t drum shaped like the one in the video, it was a rotating disc more or less. Again, turned out it has been tried before and didn’t seal 🤷♂️.
Have a look at Coates international, he actually got it done and they ran like a champ. These offshore unlimited racing for quite a few years.
This comment should have more likes. Many inventions in the past have been invented simultaneously by multiple smart people who sat down and thought about the problem. However we only remember one of them, because of our innate human urge to glorify hero's and defend them religiously against anyone who dares to question our believes.
This not only hurts the others who deserve equal credit. But it also discourages people to pursue ideas, because common folks cannot have good ideas in this world view. "Who do you thing you are to have a good idea?" type of thinking.
Also if their solution works and they have cracked the problem, then most likely they get bought out and the patent disappears somewhere in a drawer. In practice the use of most patents is to keep others from breaking the status quo with a new invention in "your" market. Patents usually mean a 20 year delay for the mass adoption of an invention.
I think you should give yourself a bit more credit than that. You are just as brilliant as the person who first thought of this. The mind of an engineer is incredible
I did my Masters degree in university on Rotary Valves engines . Not only do they breath better, but their volumetric efficiency bandwidth is wider, meaning there is no need for variable valve timing for normal road going cars or even high rpm race cars.
They work best with any forced induction. A small 1.5l engine could easily achieve 500kw (670 hp) assuming the engine can handle it.
Also since there is no piston/valve collision risk, the valve timing could be much more aggressive.
40 and 50 years ago they had trouble with the rotary valve binding up due to the combustion pressure. How do they overcome that now, if they could?
@@nopenonein there is something called floating valve seals, they basically float between the head block and the rotary valve, the more the pressure is the more force the floating valve seals. A special film coating is used that has amazing anti-wear properties. Thus these two solutions help eliminate valve expansion and seizing.
I'd like to see the full airflow vs duration curve. Obviously it will flow well full open but what does it flow part open, which is most of the time?
Am I mistaken to believe that there have been several sleeve valve engines in production? Mostly for ships or stationaries, but also a couple of warplanes and such.?
I was under the impression that sleeve valves were- up to this point -the most successful alternative system of valving that had been tried, but this comment section leads me to believe that the idea has been abandoned.
At 3:39, the statements made do not seem to align with the photographs of Normal / Valve Seat Recession. I noticed this.
I just discovered this channel today. I'm a mechanical engineer with a licensed automotive technician background. Yes , I'd like to strangle myself some days. Moving on. Very impressed with your presentation of the rotary valve. It was explained in such a manner that the average person interested in such a topic would understand. I don't think my 31 year old daughter with 4 little kids would be even slightly interested. She hates when I talk technical about anything. Very well done sir. I will definitely look into some of your other videos. Thank you.
Yes, my wife glazes over and says "Uh-huh"
@@doncahala7326 Same here. And they want "more women in STEM fields". Shame
I did! 🙋♀
@@montre-moi What a stupid comment. My daughter is a mechanic.
So, as a mechanic I've got to ask who did what with your wives, because it's clear that you guys have a grudge!😂
As an automotive engineer for 37 years, I love the way you deliver your knowledge on an easy to understand level for all.
i don't, anyone clicking on a topic like this has a pretty good understanding already or they wouldn't care...
@krebgurfson5732 this came up on my recommendation, I am in no way involved in this field ( I'm in the medical field) but his explanation was clear and easy to understand. I think making the effort to make things understandable serves to introduce these topics to a wider audience and get them interested even if it makes the experts feel like it was too simple or lacking detail.
ive been an automotive engineer for 38 years wow look at us go
@@krebgurfson5732I have nearly no understanding on this sort of topic, and yet this man made it incredibly easy to understand, so you're talking out of your arse
Back before the last ice age when I was an apprentice mechanic, at Fords training center there was a 6 cylinder engine with twin rotary valves. This was a live and working motor that was in the dyno room. The normal pop valve 6 would rev to max 6500 RPM, the same engine with the rotary valves would rev to 11000 RPM, the weakness was the bottom end. The pop valve 6 would make 147KW power and 287NM torque at 6000RPM and 3000RPM respectively. The rotatory valve engine 235 KW and 315NM at 8000RPM and 3400RPM respectively. Great video on this topic.
Wow! Thanks for wisdom and positive feedback from ice age! :-)
What volume did this engine have?
The only issue that Ford had was the lack of flux capacitors. We’re experimenting with some right now and its been very promising.
@@AdamEarl2 i hear doc brown is working on it
So the bottom end needed to be robust but otherwise it worked great? Sounds like something too good to be true. Since my own Ice Age vehicle a 71 Ford with 351 Cleveland it's wild to see how much progress there has been on engines, including computers, injection, friction-reduction, metallurgy, modeling, boost, etc.. from back then and same goes for the ultra strength steels used to weld up cheaper unibody frames and bond together fancier frames. I think the biggest barrier today just as in Congress is battling with dinosaur technology hogging the roadways. Super light cars can be made but they won't survive impacts with heavy vehicles. Ideally I think we need heavy vehicle lanes and light vehicle lanes, or just separate streets/roads.
I brainstormed this idea in the early 00's. I couldn't find any info on this being done and I thought I had a unique idea, until now, thanks for shattering my dreams.
I did the same 20 years ago in the shower for automatically folding rear wings and front aero that alters drag depending on cornering and speed like Ferrari did 😂😂😂 not even making it up I was only a kid with a cast model of a Modena
Relatable
Very nice presentation. Great sequence of aspects. Not too many people can be so clear and coherent and not leave out anything needed to understand and not put a bunch of confusing extraneous info in. Good job.
It never ceases to amaze me how not only is a valve train capable of doing that so fast, but with proper maintenance it can do it for such a long time... My 2000 AU Ford Falcon ute (Australian pick-up basically) for example has done 510,000km and she still functions like the day it left the factory, never uses a drop of oil and gets the same fuel economy as it did new. It's never, ever let me down, not even hinted at it. And I use it tow and all sorts, so it doesn't live the easiest life. That intech in-line six is the definition of a workhorse, a truly great example of engineering the right tool for the job.
Sure she's well looked after, but it amazes me every time I turn the key and it works perfectly. It's one of those cars I bought as a cheap work car stop gap and now I never plan on letting her go, BEST car I've ever owned. Even more reliable than my 70 series TDV8 LandCruiser, which has let me down twice and cost ten times the money I have into old Ford.
Now that's reliability.
Yet Toyota advertise on reliability. It's pathetic
@@Low760 Yeah don't get me wrong, the 'Cruiser is an absolute beast and I have it because I use it for going places the Falcon just can't... But she hasn't been the most reliable thing and my word is she thirsty when you ask her to work. It can chew through the 110l tanks in an eye watering amount of time.
I have it because there's not really anything else out there that can do what it does, but I could sell it if I didn't need it. I don't absolutely love it. The Falcon I have because I absolutely love that old thing.
I'm gonna rebuild the drive train and put a turbo on it when she finally does let go, or the clock hits the full million. Whichever comes first. Probably the former at this rate.
We'll do a 10 second 1/4 mile sleeper build, leave the outside looking all weathered and worked, but give 911 Turbos something to think about lol. Ya know what I mean.
But no Barras, everyone swaps out the intechs for Barras. The intech deserves so much more love.
Edit: I mean probably the latter at this rate. I think it'll go the full million.
Up the mighty AU! (I have an xr8 AU ute, it only has 360,000ks though)
@@mangomcpoo475 It really was peak Aussie engineering. They're never gonna make them like that again.
Lol here in states my F150 has 600k miles and is the same reliable. Not bad for a 60 year old design in use for 30+years. Long live the 300.
This channel is great weapon against cynicism and lethargy. I don't want to wax poetic but your videos really lift my spirits up and give me food for thought! Cheers mate, great video as always!
I think you're just saying that but I don't feel like doing anything about it
Only someone who's never actually built anything will call ease of repair, reliability and the entire system of replaceable parts that simplified machinery to be 'cynical and lethargic'. Reliability will trump novel designs 100% of the time.
Whats interesting is how hard YT now works to keep that ignorance and lethargy in play on certain subjects by censoring anyone who dares expose said ignorance and lethargy for what it is.
@@Benzley722 Except too many of the things we use every day have nothing in regards to longevity and efficiency built into the designs.
Best articulated explanation of valve operation i have seen.
Your way of explaining things is pure perfection. I don't even care about cars that much, but I'm subscribed now. Thank you!
As a 77 year old who first rode a motorbike at 16 and have since carried on with motorbikes and cars also buses and trucks.this amazing man is the best expert on engine's of all types and his knowledge and the way he explains everything is great
I totally agree 💯
It was boring for me, nothing of value that I didn't already know.
Ok Steve.
I like your channel btw Steve. Super full of your all knowing knowledge
it sounds awesome because the video is totally, surely, 100% unbiased lol
Not sure where you went to engneering school, brother, but if you ever get tired of content creation, you really should teach at a major university. Your enthusiasm and ability to explain things clearly and make challenging topics easy to understand is just fantastic! Definitely the best automotive engineeing channel on the interwebs.
True but, the Internet is subverting just about everything the university can do except accreditation. Plus universities are starting to lose respect as costs continue to rise with the number of graduates who can't, or won't, find work to repay the debt.
@@stevenwilliams1805 I guess engineering graduates will be able to find jobs.
Why would you want him to shift from teaching in a super informative, free way to instead a way where the people learning are now paying him directly rather than RUclips paying him, they're less engaged with it since its being taught in a university setting, and he now loses freedom in when to work/make content? Formal education isn't everything, you can learn A LOT from the internet.
Pretty sure he had a high level government job before starting YT. Don't believe he ever studied engineering formally. Certainly shines as a communicator.
@@Part-TimePro As someone prone to hyper-focusing on a new interests/hobbies every 4 or 5 years, the internet has been my go-to for theory, practical knowledge and "know-how" over the last 30 or so years. It has always felt like such a special time to be alive. However, I have noticed over the last few years that quality content, where you come away feeling like you have learned something, is getting HARDER to find, not easier. Where once platforms like RUclips were primarily about sharing information, my sense is that today it is more a side- or main-hustle for "content creators." Everything changes, and I accept that - but the focus on likes, clicks and views, as opposed to the an honest and good faith sharing of knowledge, is both sad and sick.
But perhaps it is just me on the cusp of pre-senile decay, howling into the digital ether... but, I don't think so. Not yet, anyway...
I'm a chef by trade, I don't even have a drivers license... yet I love videos like this. It's super interesting listening to someone talk about something that I lack any real knowledge about and doing it in a efficient and entertaining manner!
You also might like Munro Live, he takes apart cars and finds the costs associated with each part, looks at design decisions, etc. Tesla is a big focus since they're innovating like crazy, wiith lots of changes month-to-month, tiny things to make it easier to make or more reliable. "The best part is no part" optimization of removing/combining parts is fun to see.
Very good description and demo of engine valves and their problems. Yes, the rotary valves always leak because of the necessary clearance to permit rotation but also allow for expansion. A solution is four longitudinal seals on the barrel, as used on Wankel engine lobes, but that introduced a lot of friction and heat.
Of course, the other alternative to poppet valves that actually made it into production was sleeve valves.
Yes and they were a huge pain in the ass to make. The sleeve has to ground to size with A DULL GRINDING WHEEL at 10X the power and 100x the time requirements of normal centerless-ground parts like wrist (gudgeon) pins.
It was so bad Napier whined to Churchill who whined to Roosevelt who ordered an entire year of the Sunnen Corporation's centerless grinder production (about 2000 machine tools) to be sent by ship to Blighty.
The USA had to fight WW2 without the use of the finest engines ever made the C-Series Pratt & Whitney R2800 because of that year without enough grinders.
Indeed. Most notably used in the Bristol Hercules engines fitted to the Beaufighter.
They kind of remind me of the valves in an opposed piston engine.
A really interesting solution.
@@patrickshaw8595 By that time the Brits had more than enough German POWs. Germans are well known for their precision engineering. So, why didn't they get some of those to manufacture the sleeves?
My grandpa worked at Bultaco for most of his life, they experimented with 4 stroke engines with rotary valves, iirc they never made a production engine because of sealing issues and burning a lot of oil
' because of sealing issues ' Exactly, hard to beat the 'tends toward self sealing on pressure' action of standard valves.
It seems like you have two choices. You have a rotary valve that is sealed by a layer of oil, which gets burned by the engine and increases emissions. Or you have a rotary valve that seals because of tight tolerance, which means high frictional losses (greater than the valve springs) plus decreased service life.
This seems like a great option for a race car that gets rebuilt every week, not so much for a daily driver.
Seems like a trend with rotary things in cars
Bultaco was super cool!!
@@d4a Im currently restoring my dad old Streaker with the watercooling kit my grandpa and dad made for them, the kit parabellum. Its so cool to works on those old bikes and see how stuff evolved over time.
I don't know why RUclips popped this into my feed, but thank you! So interesting. I'm a physicist, so I appreciate the very high pressures and tight tolerances to prevent gas escape, but unfortunately the tremendous friction that a tight seal generates is the Achilles heel of a rotary valve that probably doomed it, not to mention the expansion of the valve when exposed to such extreme heat in a combustion chamber.
As always my friend, your videos are really interesting and stand out from the vast majority of other content creators' videos and topics in general.
I worked at a company where one of the owners was involved in the prototyping of a rotary valve head.
Along with the sealing difficulties, he explained to me that one of the big drawbacks was poor airflow when the opening was misaligned. They were able to improve it by adjusting the shape of the porting, but it was not as good as a poppet valve when it is partially opened. Additionally, when the port and spool was half opened, for example, the fuel and air flow would separate in an unpredictable way. Ultimately, they abandoned it because it was not better than poppet valves and WAY more expensive.
Literally what I imagined, nice in theory but a huge tell tale sign would be if it made more horsepower, I would love to see that dudes project versus the standard engine because I can’t imagine too much more horsepower than the normal poppet valve we have
@@benjaminwatson7868I mean I’m also curious but… while the efficiency is the goal for most applications it isn’t the focus of this video whatsoever
My biggest take away from it, is that for SIMILAR parameters we can have SMALER engine with LESS parts and thus lighter machine overall with possibly less noise/vibrations but that is said by a company that try’s to sell it so idk
Yeah it wouldn't be hard to fix any of that tbh. The only legitimate problem still is sealing.
I've run a rotary valve 2 stroke. It wasn't much at low RPM, but holy hell, it would run on the top.
I think the "separation" of air and fuel flows in a processed mixture (carbureted) is no longer an issue with injected engines
My thoughts are the same as others. This guy was excellent at explaining things. It's like every word he used was needed and every word that was needed was used. Great teacher for sure.
A very interesting, excellent presentation, you have put across complex technical issues in a relatively simple an understandable way. Thank you!
Great presentation! My Great-grandfather Benjamin Augustine and his sons were rotary engine inventors and manufacturers and put them in cars, planes and industrial equipment bank in the 1920's and 30's. The engine was called The Augustine Rotary Engine. There are a few articles about it on the internet. Sadly it never took off the way they wanted and the big car companies were not interested in that type of engine.
Rotary valves in ICE were very popular concept 60-70 years ago Down Under (Australia and NZ) among motorcycle racers. Latest try was the Bishop rotary valve in Formula 1 some 20 years ago and they had a working prototype going up to 18500RPM. They said that V10 3L engine would be around 75kg with rotary valves design. But as many times before F1 regulatory body made mandatory use of poppet valves and that was the end of that story.
The only living project with rotary valves is from some enthusiastic owner of BMW E36 in USA who converted his inline six M52 engine to rotary valves engine and that hybrid engine works quite nice for garage build.
Unfortunate
As usual, professional racing shanking interesting new technologies in the cradle...
16:56 You forgot to take in a count that it actually takes half the effort to spin the cam shaft.
Furthermore, this is due to the camshaft spins at half the speed as the crankshaft, 2:1 gear ratio, cam to crankshaft timing chain/belt relationship.
Also keep in mind, that once the valve spring(s) is compressed, their is energy stored in the valve spring pushing against the camshaft that's trying to spin the camshaft. I'm shure you have experienced this first hand when trying to spin a camshaft in a cylinder head. Moreover, this compressed energy storage in the valve spring isn't completely wasted.
I'm just giving you something to think about.
your fan always.
It is true that some energy is recovered.
@tonyduncan9852 the vast majority is recovered.
The only losses are friction and the inertia of accelerating the valve.
Vast majority? As an answer to _some?_@@mircomuntener4643
@@mircomuntener4643 things that are unavoidable, even in a rotating valve.
@Benzley722 the rotating valve will not have inertial energy loss because the valves do not reciprocate, but will have significantly higher frictional losses fuel to the nature of the seal.
The inertial losses of the poppet valve is negligible, particularly when compared to that of the pistons and rods.
I included it to satisfy the galaxy brain that would otherwise correct me on my egregious omission.
The way he says “so” is priceless, love the videos
Man I feel I learn more in 20-30mins watching your videos than at any other time in my life!
Coates Engineering in Wall Township NJ started working on rotary valves back in the 1970s. A friend worked for Coates. They had several 5.0 L Ford V8s modified and running with rotary valves.
For clarity on Ducati Desmo service intervals, my 2023 DesertX requires Desmo service every 18k miles. That's similar to service interval for motorcycles with valve springs.
Coates had plenty of longevity problems.
The valve adjustment interval on the earlier ones was 6000 miles. VWAG buying Ducati actually wasn't a horrible thing.
@@georgelane3564
For clarity, rotary valves have longevity problems.
I checked the valves on my Yamaha R3 at 40k km (24k miles), they were perfect, no need to adjust valve clearance. The service manual says that valve clearance checks are at 20k miles.
I remember the building Coates was in. I went there in the mid 70's when it was a car museum. I don't know about now but Coates was there in the 2000's.
I'm not a mechanic. I love engineering and science.
So many light bulb moments understanding internal combustion viewing this channel. You keep it simple, explain the history and future on everything you produce. Especially the "why" in your channel..
It should be played in every highschool and trade training 🙌
Thank you all the way from Tasmania, Australia 🦘🇦🇺🍺
Yes, he gets to the core of things you know you should have questioned all along.
They're booked solid for videos about choosing genders, and they have no space for math or science anymore.
This is a fascinating subject. And very well-presented! Thank you for doing this.
perfect presentation of an interesting topic, you put incredible effort and love in your your visuals and your explanations are clear and vivid, makes your videos always fun to watch ❤
I have a 1918 "automotive service and repair" manual. With exception of electronic engine controls, there is almost no technology that hasn't been thought of and tried. In that manual, there is a reference to a tubular valve engine, which has long tubes within the cylinder head, one for intake and one for exhaust. These tubes would rotate with passages opening into the combustion chamber timed to allow intake or exhaust into or out of the cylinder at the appropriate time. The tubes are fixed at the end of the head to either the carburetor or exhaust pipe. That book has so many cool innovations that have been lost to time, it might be worth a look for some "NEW" ideas. Especially now with our better metallurgy.
It kind of makes me wonder how we got to such a ubiquitous engine design. Is the current set up so much better than it outweighs all these other options...
Sounds cool. Do you know the publisher/authors? I'd like to look this cool book up.
Well - a good example is Mazda and the rotary engine.
Many companies tried rotaries in the 70ies and 80ies - but finally gave up as sealing the combustion chamber was an issue that couldn't be fixed with that days' tech.
Mazda kept tinkering for decades - and all other companies were like "they never get it to work properly".
Finally - they made it. They found an alloy strong enough for sealing the rotor tips. End result: Mazda RX-8. A bit thirsty - but robust and high-revving.
Basically the same story was an engine running partly like a diesel and partly like a gas car for maximum efficiency. Mercedes tried it (called Biesel - German for Benzin+Diesel) - and gave up. Not possible.
Today - you can buy these engines (Skyactive X) in various Mazda models.
Point being: Many old ideas work great with today's technology.
@@JohnSmith-of2gu I've moved a couple of times since I saw it last. It was copywrited in 1918. It was just by chance that I found it. I will dig through my stuff and try to find it.
Probably was referencing an Elmore. They were one of the pioneers of rotary valve engines.@@russstyczinski
Great coverage. You didn't mention one large detriment to rotary valves, combustion chamber shape optimization. No matter how thin you make the supporting structure between the combustion chamber and the valve, you'll always have a very odd shape and the valve surface will always drag its exposed (and contaminated) surface into the valve's envelope/cylinder. Poppet valves are very easy to fit into hemispherical, or near hemispherical, chambers.
Ok, that helps quantify and locate a restrictive condition. Next step, prove that is NOT prohibitive or able to be bypassed or overcome.
@@gregrice1354 No, that's not how it works. You have to show a better alternative. No one is saying poppets are perfection, just that they have a lot of qualities which allow us to incorporate them into the overall design.
It would be a little silly to start our exercise by attempting to prove a negative.
This website is a discovery for me. The straightforward presentation, albeit assuming some knowledge of engines and valves, is absolutely first class.
Naturally I have subscribed.
Beautifully explained. This dunderheid had no difficulty understanding this wonderful presentation!
I'm a gearhead...noticed the collection of engines and model engines in the back ground. Love to see that! Excellent job on the video brotherman.
Quite a pickle, Ollie, a tight seal on a moving part.
What I like most about your explanations is describing something complicated, so simply, that I can understand it.
Excellent presentation with all of the pros and cons.
Well said Sir. I appreciate the effort you put into these informative presentations. Thank you.
The Bishop Rotary Valve worked. One of the design guys, Tony Wallis, did a speaking tour in Australia where he described the challenges he had convincing a manufacturer to actually use it.
Looks like it worked in racing usage... I would still remain skeptical until it sees daily driver use. Wish somebody would take a chance on it, even just for a couple prototypes to drive around in the outback
I remember reading about the Knight "Sleeve" valve engine which also overcame some of the drawbacks of the poppet valve system. They did go into production in the 1920s, but that technology didn't catch on for some reason. Might be a good topic for a future video.
Sleeve engines solved some problems of 1920'ies poppet valve technology, at the cost of introducing a bunch of its own problems. The brits did develop the technology for aero engines, at great cost, but in the end it wasn't an advantage over poppet valve technology of the time and they faded away.
@@jbepsilon It was a better performer AFAIK, but it was also a giant headache to manufacture.
@@darthkarl99The Napier Sabre was powerful, but that was because it was a high rpm and high displacement design with a whopping 24 cylinders, not because it used sleeve valves. In fact, the sleeves limited boost pressure lest they deform and seize; the Sabre was never cleared to use more than +11lbs boost operationally during WWII, compared to +25 lbs for the RR Merlin.
Secondly, they spent so much time and effort in making the sleeves work even passably (when initially introduced into service, the Sabre had a time between overhauls of 25 hours!!), that they never had time to make a good multistage supercharging system which would have been necessary for good high altitude performance.
The Bristol Hercules radial was the most successful sleeve valve engine of WWII and was extensively used in British multi-engine aircraft. However, it was about on par with similar size poppet-valve engines like the Wright R-2600 or the Mitsubishi Kasei, no particular advantage of the sleeve valves there. Due to the time consuming and extremely expensive R&D project trying to make the sleeve valves work, the Hercules was much delayed, and it's big brother the Centaurus missed WWII entirely.
Poor sealing with a lot more complexity. @@jbepsilon
Sleeve valves where heavily used in British WW2 aero engines. E.g. The Bristol Hercules (14 cylinder radial) used in the Wellington - they made 84000 of them. Also the Napier Sabre (3000hp from 37L 24 cylinder) used in the Hawker Typhoon.
Loved your masterclass.
Greetings from Argentina
Truly great presentation. Very well done!
In plumbing, for potable water, it is like a ball valve versus a rubber washer type.
Another great informative video. Great job, as always!
There is a company in Australia called Repco, back in the day they built a very successful formular one engine, the Repco Brabham engine. If I remember correctly, they made a aftermarket head for a red Holden engine, a very popular engine for modification, it had a rotary valve set up, but it was not reliable due to the expansion as you stated, the company had the ability to build a formular one engine but could not get the head to work reliably.
Didn't know about the rotary valve from repco but have a family friend who was a machinist from the 70s on at repco.
Besides you can get lots of power from a well designed head working around the valves.
@@Low760 I don't think it went into production, I saw the head in an old Australian hot rod magazine under development and it made excellent power, it could have even been for a grey motor.
I wonder… with today’s computers could it be possible to just heat the sealing? Like preheat so it would expand and computer would keep it cold enough not to break
@@bigboy9693 yes I remember seeing prototype open wheel car barrel valve set up. Late eighty's maybe not good on time. The sound was music to me very crisp and grumpy. This is first time since then I've heard this set up talked extremely proud of you cats thank you
@@bigboy9693 it never went into production. It was an F1 engine only and they made several iterations, all of them V8s from what I understand. Used in the 1960s.
I like how I'll be thinking about stuff like this. Literally pondering if rotary valves were even a thing. And then I stumble across this guy having made a video of the exact same thing not a week later.
I enjoyed this video a lot. You point out things that really stimulate my brain to think and it's a ton of fun!
_One other major challenge with poppet valves in ICE applicatioms: Cooling. Valves have to be hollowed out and filled with sodium that melts (vaporizes?) upon being heated and makes the valve act as a heat pipe, transferring heat from the valve head to the stem for dissipation._
_Also, the camshaft lobe centerline has to be offset slightly from the valve stem centerline, so the the valve is rotated about its axis every time the camshaft opens the valve. This rotation is to prevent hotspots or physical high-spots in the valve seat from wearing down the corresponding spot on the valve head (or vice versa). The rotation equalizes wear on the whole surface of the valve head and valve seat._
Only very high performance exhaust valves are sodium filled. Most valves are solid. Could still be incorporated in a rotating valve. I think the temperature limitation is still at the seals.
Your observation that camshafts are somewhat offset is true, but not a necessity. This idea would likely work better with double valve trains, enabling a four valve head with single ignition and duplex injection at the centerline.
You will not find sodium core valve in a basic production engine the cost is too high and cooling gain and life cycles payback is not great enough to offset the cost. They are common only in extreme hyper cars/super cars / hybrid racing engines / or cutom builds . As for offset you will never get a true center on center position do to the valve rocker being on a fixed pivotal point the pivot point would itself need to follow a scribe arc - they have over the years tried to address this in various ways so the lobe was followed with an expanding arm so the rocker to stem stayed on center of cam lobe and the end overthe valve stays align using an end shaper like a golden arc . Just the simple geometry of the rocker arm being a fixed solid piece as valve mover the lenght of the rocker arm to stay on center line needs to lengthen so a valve train no mattr how you make it gets complex so he K.I.S.S. process is simple fast dirty set up
@@DMPB-fi2ir most tappets and bucket style, the cam is offset slightly on the lifter to rotate the lifter rather than operate purely i sliding im pretty sure thats what the quote was refrencing.
Both problems solved decades ago, for low or even no cost.
not something I have to worry about on my bone stock 5.3 truck engine.
3/24/24: Excellent, well illustrated explanation of the advantages and disadvantages of today's poppetvalve valvetrain. As a youngster I owned a Vespa scooter, which was a 2 stroke design that required only a 2% oil mixture. It got over 100mpg too. While it did not have a rotary valvetrain and instead utilized standard 2 stroke side port design, it worked flawlessly. Smog emissions were low for it's time. It cost less to manufacture and had a higher power to weight ratio than 4 stroke engines. Your rotary valve demonstration reminds me of that 1965 Vespa engine. Retired in Sacto.
Vespa two strokes used the flywheel as a rotary valve with carburettor connected to crankcase rather than cylinder as most two strokes using piston to open and close ports
50cc two strokes stayed relevant compared to 4 strokes longer than than for larger capacity because of two major reasons regulations and tuning. (and to a smaller extent 125cc)
50cc was the only way for teenagers to have transportation between 14 and 18 to in many places in Europe. or 125cc 16+
kids love to be independent and have transportation but they also love to race, and go fast. 2 strokes was the only way to have good performance stock (after derestriction) and also to increase performance massively with rather simple upgrades (exhaust, carb).
If 4 strokes were given 2x capacity rule like MotoGP got vs gp500, 4 stroke would probably had prevailed sooner. now 2 stroke is progressively disappearing from markets due to emissions. direct injected two stroke was a big thing when it came out regarding mpg emissions and reliability but it was already too late and Aprilia never managed to bring this promising tech to larger capacity engines.
thinking about it, Aprilia ditech directly injected two strokes would deserve an in depth video by @driving4answers
A British Engineer had one running in the 60’s or 70’s. It worked very well with very wide torque band and excellent efficiency. The problem they had was during the firing of the combustion stroke, the rotary valve bound up due to the pressure. It created a varying load on the rotary valve through the 4 cycles. They tried loosening tolerances but that just made it burn oil. It was a great prototype but the big manufacturers didn’t invest in it.
Surely opened my eyes. Well demonstrated..
In the 90’s some rotax two strokes had rotary valves on the intakes. They were different than the ones in this video, though. Instead they were a big flat disc with a slot cut out to allow air/fuel flow through it.
Yes I remember them, great engines as were the RG500 Suzukis.
Rotary disc fuel inlet valves would not work on 4 stroke engines as the inlet port needs closing ''solidly'' e.g. by a chunk of metal. A disc valve which is only 0.7mm thick (Suzuki RG500 spec) would be obliterated under compression / ignition forces.
The rotary disc valve works in a 2 stroke because the piston physically closes the inlet and transfer ports for compression / ignition - the combustion chamber has no valves or ports.
Suzuki has used rotary valves also.
@@notsofast2539 And Kawasaki, Yamaha, MZ, Bridgestone, Konig, Aprillia, Cagiva and many more. The rotary disc valve is very efficient 2 stroke system and allows asymmetric port timing - inlet controlled by disc, exhaust by piston.
The disc valve is only working against the intake side crank case pressure, not white hot combustion pressures.
@@howardsimpson489 Yes in a 2 stroke as it was designed for
. The original thread was replacing poppet valves with drum type rotary valves which would be exposed to combustion pressures. The disc valve just sorta sneaked in !
7:43 I did NOT hear that valve fall. where did you throw it man? WHERE DID IT GO???
An ordinary man of ordinary strength just launched a valve into orbit.
Don't worry it fell straight into one of the Bugatti W16 cylinders and did something funny to the engine.
@@jayartz8562 man, i love the comment section sometimes :D
@@jayartz8562 It'll come around and hit him in the back of the head when it hears what he was saying about them!
The backrooms
Thanks for this nice explanation, as usual very clear!
Thanks for this. This was really interesting. If it ever becomes mainstream, I'll guess that common failures that mechanics see will be reduced or lost compression caused by rotary valve seal failures. If manufacturers adopt this and keep the service side of things in mind, they'll try to reduce the labor required to reseal them. For example, a way to de-tension and pin the timing belt/chain during valve removal so you don't have to redo the entire valve timing, and all while only having to remove a valve cover and maybe a top portion of a timing cover.
One of my absolute favorite channels. This was a very clear and concise video, and you explain things like a pro
M.A.N. & many others experimenting with rotary valves found that rotating them the other way improved sealing & thus wear compared with the valve you show, I believe they settled on a pair of contra-rotating discs with ceramic faces though this led to a portion of the cylinder head being excessively thin unless they used the valves _as the cylinder head_ thus magnifying sealing issues again & requiring a gap in the side of the piston crown for the injector which led to wear & sealing issues in the bore.
thanks for finaly demonstrating valve systems.
That was an excellent video, even for me who doesn’t know a lot. Thank you !
A ver hands on explanation to the problems of rotary valves, so simple yet difficult. Thanks for this loved it.
Im 64.
I drew up a rotary valve engine when I was about 18 years old and sent it to a technology company called Sarich in Western Australia. They were kind to me and told me It would not work.
You can actually use just one rotary valve which is both the exhaust and inlet. This helps to cool the valve. A ceramic cylinder is probably the way to go but timing is an issue.
Was there not a rotary valve head developed in South Australia? the name Clisby comes to mind back in the 60's,it was a long round piece of metal with flats machined in it that doubled as inlet and exhaust, it sat in half rounds on top of the head, I think that the downward pressure required to keep it tied down [as it became the top of the combustion chamber] may have worked against it as it had to act as an effective seal but still able to rotate and be lubricated in some way, maybe today if retried, emission stands might be a problem. There is something on Clisby if you go to Google.
I do also remember that. My design had the port going through the rotary valve which gave more sealing between the ports and the chamber. And it had higher compression.
Honestly I don't think they will solve the sealing issue and as the rotary valve heats up it will bind too much.
So from what I understand from this video... We've been working towards the local maximum of the poppet valve and now some people and companies are looking into working towards other local maximums (in this case the rotary valve). Neat!
Great presentation: For many years I have been wondering about how to make rotary valves work. It looks like other people are making great progress on this problem. It also reminds me a little about sleeve valve engines.
As far as problems are concerned, I see emissions control as a possible problem.
As far as spark plug placement is concerned, I suspect that dual plugs might solve this problem.
You should see how 2-stroke vespa scooter utilized rotary valve for its engine. And they are considered mainstream scooters back then.
They are unique because they use the crankshaft web for the valve mechanism.
And Suzuki RG500 as well.
@@robertomalatesta6604and in the 70"s Kawasaki 100cc 2stroke race motorcycle.
Most of the two-stroke model airplane engines I ran in the sixties, seventies and eighties had rotary induction valves built into the hollow crankshafts. That was the standard then. A tiny handful used reed valves, as snowmobile engines do today. At any rate, the rotary valve did a great job. Of course, being on the intake side, it wasn't exposed to combustion gasses or temperatures.
Trabant 601 uses rotary valves on the crank webs, too.
Back in the 1970's as a teenager rotary valves suddenly struck me as a great idea to control gas flow through an engine, quickly drawing up my idea fag packet style I rushed downstairs and showed my basic idea to my father. Hang on a minute says my father and takes a book down from the book shelves opening the book and flicking through he stopped on a page and showed me a drawing of an engine using an almost identical system. The book was a fantastic
encyclopedia of engines of all types, unfortunately my father gave the book away many years ago and I no longer have it as a reference but as a teenager it really broadened my horizons as to the possibilities many many engineers had explored. My Father had designed an engine himself as a student at Loughborough college in 1947 a twin cylinder two stroke very light weight and compact 250 cc motor cycle engine, instead of a crank shaft the pistons and con rods ran in an orbital gear arrangement, dad later discovered that this idea had already been explored in the previous century as a steam engine. of course the idea was revisited in the late seventies as a four cylinder four stroke engine built in Australia named the Orbital. That to did not take off.
This dude is such a treat to listen to. Gerat videos.
Just discovered your website. I have seldom seen someone with so much talent and passion explaining complex technologies. Thank You and you bless us all with some of your talents.
Ok boomer
Historically they have been rotary valve systems in the past, Aspin in 1939, before this Crossley Brothers in 1886, even Roland Cross in 1922 to name a few. Some of these have been revisited since and with advancements in metallurgy, sealing tech and bearings have become more viable, and I think ceramic coating of combustion parts would make an improvement to their temperature tolerance.
The Aspin conical rotary valve is an interesting concept. I have an old mechanical book covering it in great detail. They even produced a flat 4 aero engine with the Aspin valve system fitted.
That being said, your videos are very interesting and instructive. Very well built. I'm a fan.
I would go back to college and get my engineering degree if you were my professor throughout. I learn SO MUCH from your videos, the narration, the animations, the graphics, that you are a new world order for explaining complex subjects. As it is, I'll just keep watching from here. Thank you.
Informative and entertaining as always. Keep up the good work, these videos have some of the best information available on engine tech and are an absolute blessing to engine heads everywhere.
Oh perfect! Just as I will drive just shy of 4 hours this evening and then again tomorrow. This brings me right into the mood! I drive a VW Golf 6 1.6L Turbodiesel Frontwheel-Drive Stationwaggon with 298000km but it is super fun to me. I attribute the fun to the horizontal stabalizers and the turbo of course. Heel-Toe Downshifting, Double-Clutching and all other good stuff I learned as of last year. The videos you make deepend my knownledge about the whole drivetrain which makes driving so much more enjoable. Keep up the good work!
I suspect that lack of emissions compliance and detuning has a lot to do with it still being reliable, fun and fuel-efficient to drive.
@@illbeyourmonster3591 Could you elaborate on that? Are you implying the Diesel Affair at VW and others in Germany a few years ago?
This channel deserves at least 3M subs. Every video is a pleasure, first like, then view! Thank you for the brilliant content!
As always very interesting and entertaining. You're definitely gifted person. Please dont stop.
The rotary valve I'm used to is from the rotax engines. Its just a flat disc with openings that sits over the intake ports and rotates in time with the engine. Surprised rotax engines weren't mentioned.
Also the Rotax engines make more power per displacement do to intake timing advantages.
@@garycarbonneau499 yea I use them to swap into the old honda oddysey and pilot mini buggies. Currently running a 670 H.O. that makes around 140hp. Always joked that I have the largest collection of snowmobile engines without ever owning a sled. Have a wall of 583,617, and 670s just stacked up. I'm in Southern Maryland we barely get any snow.
This is for the intake valve on a two stroke, the valve is not subjected to combusion pressures and temperatures, it would not work on a four stroke.
seems like a neat idea for single cylinder engines as the barrel can function as a balancer shaft against vibrations as well reducing the needed parts even further.
Even my wife watches attentatively when you explain technical car stuff....well done. Thank you sir?
Love this video. Great to learn something and this approach to valves was new to me!
I built a rotary valve cylinder head for a Honda 90 as my senior project in 88/89. It runs but lubrication and sealing are serious challenges that few have overcome.
I run rotary valve rotax snowmobile engines in all 4 of my 85 honda oddysey fl350s.
@@shifty1927 - Isn’t the Rotax rotary valve a 2-stroke? I believe Kawasaki popularized this in the 1970’s.
The valve described in the video is like the one I made and maintains a 4-cycle combustion process.
@@Alaska_Engineer yea they are 2 stroke.
@@shifty1927 for 2 strokers, rotary valves have been around for a very long time as mentioned. Rotax and Kawasaki come to my mind as well. But, remember. The 2 stroke rotary valves only deal with the intake charge (no hot dry exhaust), only deal with low pressure in the crankcase before the fuel transfers into the cylinder. Not the high cylinder pressures achieved during combustion. But, I get what you were thinking.
@@ironken1796 Cool and yea that makes sense.
When you first said rotary valve I first thought of the Saber and Hercules engines of WW2 aircraft but then I remembered these were sleeve valved engines. Then I recalled that steam engines also had issues with rotary valves.
Steam engine people have a saying "there's two kinds of valves: poppet valves, and those that leak".
@@jbepsilon that applies to all engines. Just cause a design is old doesn't mean it needs to be replaced. Wheels are stone age technology. Guns are medieval. We're adjusted the mechanism which guns are fired and the powder and projectiles used but we never replaced the barrel with something else because it was 'more efficient' on paper.
great job with the production and delivery of information in this video
Smart man & very relatable, I wish I had a teacher like him in shop class.
These have been around for years. The failure of the design is that combustion gases get around the barrels, kill the lubrication around the barrels and they fail. Sleeve valve engines, which have a vertically aligned barrel, were used in WWII, such as the Napier Sabre, but suffered from reliability issues.
Another couple anvantages of the poppet valve: it's sealing surface is self cleaning and the friction surfaces (valve guides) are cooled by the intake charge so oil doesn't cook and gum up the movement.
Heat is also transferred from the poppet valve to the head when it is seated.
The sealing surface is only self cleaning on port injection engines. Ever pulled the intake or heads on a DI only engine? They get pretty nasty without fuel washing the valves.
The exhaust valve guides aren't cooled by the intake charge.
@@pastaalalamborghini There's still an element of self cleaning of the sealing surfaces on engines where the valves are allowed to rotate in position as they open and close. I'm not sure whether this is common, but some engines have the valve stem slightly offset from the center of the cam to cause this rotation as the valve opened and closed, which reduces fouling on the sealing surface, though it won't stop things getting gummed up everywhere else.
@@peglor ...valves that spin themselves against their seats to self clean ... Bye
Brilliant explaination! I think we will still be using combustion engines for years to come and this could make them more efficient.
What absolutely excellent video. This is the top tier of the internet. Thank you.
As a mechanical engineer with a master's degree, I am so happy with the topics and the anecdotes that come with your videos. This is just great. Thank you for the nerdy entertainment.
People who regularly deal with plumbing know how difficult sealing rotary valves can be....
Not really. That problem is just a sad reality behind the lazy engineering of legacy, "good enough, so why change" systems. If someone without an engineering background can build a custom house that swivels using custom joint seals for plumbing designed for easy maintenance less often than you'd need to reshingle, "real" engineers don't have any valid excuses.
'how difficult sealing rotary valves can be....'
Exactly, that was my first though off hand. Poppet valves are reliable, most engines last 200K miles etc, pressure makes it want to seal instead of blowing by gaps, and so on.
If rotary valves were really better, everything would already be rotary valves. People in the 1930's, 40's, and 50's were geniuses and then some and trying everything. Rotary valves would have taken over ages ago if they were better.
I'm not sure the analogy works because we are dealing with air flow, not liquid, and we don't need a perfect seal, unlike in plumbing where a perfect seal is required.
@@madeconomist458 Air is worse than liquid, not better. ' and we don't need a perfect seal' And you'll be cooking the oil needed, a very bad idea.
It is not 200K mile reliable tech.
@@madeconomist458 "we don't need a perfect seal" that doesn't even apply to my 1930s lo compression cast iron flathead model a with only 40hp and 2200 max rpm...
I have leaking valves, and a significant drop in the little horsepower i have... Even more noticable in the loss of torque.
The thing is, that yes, with poppet vales, if your seals aren't microscopically perfect, the pressure from the combustion will press them shut anyway.
But with rotary valves, this benefit is lost, so the higher the compression the worse the leakage
D4A, you always approach new developments with candor and vigor. Love it. Something along this line came my way via the YT Algorithm; Jim Ardeema has developed a totally mechanical method to achieve VVT in a DOHC- not quite the revelation this rotary valve would be but increasing complication has led to a lot of unrepairability for modern cars. Se Greg Quirin's channel- the team of Ardeema and Braun have been at this for several decades, so not Millennials at all! Keep up the good work- fascinate us as often as you find the new waves to work with!
This guy has got to be one of the best at explaining things 👏👏👏
Thanks for these understandable videos!
Direct inject two strokes are very clean. They don’t have fuel washing oil of cylinders and bearings so can run a much smaller oil flow. Fuel is injected after all ports have closed so there’s never any unburnt fuel going down the exhaust. Exhaust power valves maintain midrange power and there’s no partial combustion to slap the piston around - much less bore wear. The Rotax ETECH is cleaner than competitors four strokes and has better fuel consumption. It can use stratified charge solving NOx issues. The pre combustion chamber used on F1 engines is an ideal fit as the excess air can be varied via inlet valves.
That's a fascinating little improvement for engines!
Very good presentation of the subject. Very easy to understand and participate in the thinking. I wonder if anyone has thought of using the wiper seals in the style of the Mazda rotary engine. Those have to withstand the same pressures and temperatures that a rotary valve seal would.