Twin Rod Avadi Engine - Perfect Balance in a Single Cylinder - Genius or Just Another Pipedream?

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It's time to review another novel engine design and today we are going top inspect the Avadi MA 250 engine. As always I’ll explain what makes it special, how it works, the strengths and weaknesses of the design as well as the potential for it to enter mass production.
So as you can see this is a rotary engine, but it’s not rotary in the way that a Wankel/Mazda rotary engine is. This is still piston based with the big difference between this and conventional engines being that here the entire cylinder rotates within a casing and we have two connecting rods and two crankshafts for one piston. The crankshafts are geared to a stationary ring gear.
When I saw this engine for the first time the first thing that came to my mind was “hey this a big gyroscope. The cylinder spins in this direction, the crankshafts spin within it, kind of like a gyroscope. Ok that’s interesting….but why? There is no inherent benefit to making an engine cylinder together with the piston rotate around an axis so why do it?
To understand why we must observe how is the cylinder spinning. The spinning is done via gears. Why gears? If you want to make something spin there are more efficient ways than gears.
If we look at the Avadi website we will see they claim that the gears provide a reduction or torque increase for the engine. And yes this is of course true. All geared transmissions work on the same principle.
If we take two gears. A small input gear and an output gear that is twice the size we will double our torque output. This is the same arrangement as in the Avadi engine the pinion gears on the crankshaft are half the size or half the number of teeth of the fixed ring gear. So if we imagine that have an input speed of 1000 rpm and 10 Nm of torque at the small gear than our output speed at the large gear will be 500 rpm and the output torque will be 20Nm. A gear that is twice as large halves speed and doubles torque. This happens because the larger gear has a greater circumference and therefore the distance from the teeth to the center is doubled. When we double this distance we double the leverage and thus the torque. The speed is halved because for every two revolutions of the small gear the large gear makes only one revolution, so we have a 2:1 gear ratio.
So yes, the geared arrangement does increase torque as Avadi claims but this is NOT the reason why they implemented this solution. If they were interested only in torque then they could have done a 4:1 gear ratio and quadrupled the torque. So why 2:1? Think about it, what else has a 2:1 gear ratio, what else rotates twice for ever 1 rotation of the other things?
Yes, that’s right! The crankshaft and camshaft in a conventional four stroke engine have a 2:1 ratio. The crankshaft rotates twice for every single rotation of the camshaft. Why?
Because a four stroke engine needs 720 degrees to complete a full combustion cycle. Intake, compression, combustion and exhaust - each stroke is 180 degrees of crankshaft rotation and 4 x 180 equals 720. But during those 720 degrees you want to open the intake valve only once and you want to open the exhaust valve only once. You want the intake valve open only during the intake stroke and the exhaust valve open only during the exhaust stroke. To achieve that all you need is a 2:1 rotation ratio between the crankshaft and the camshaft. A 2:1 ratio means that 180 degrees of crankshaft rotation is only 90 degrees of camshaft rotation. So all you have to do is place your camshaft lobe in the correct position in relation to the crankshaft and the piston and your intake valve will be open only when you want it to be open.
Now if we go back to the Avadi engine we will see that this engine has no camshafts, no valves, no springs no nothing but the four stroke rules still apply, with or without a camshaft. The Avadi engine has an incredibly simple valve train that essentially consists of only three holes. This is one of the main reasons why the engine is so compact and so light.
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#d4a #enginebalance
00:00 How it Works
10:54 Engine Balance
17:17 Breathing Issues
22:67 Drones

[@d4a]

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[@aceman9030]

the crankshaft counterweights are rotating thus they have some angular momentum, but in the avadi they keep revolving means the direction of angular momentum is constantly changing. do you think this could cause extra strain on the connecting rod?

[@MrLince-hr4of]

the solution is a turbo with high boost pressure💥

[@darkwater72]

Regarding the torque spec of this engine, it's not really fair to say it's "cheating" by specifying measuring torque at output shaft instead of the crankshaft. ALL engines measure torque at the output shaft. However, for most engines, the output shaft just happens to be crankshaft. But, that's only a coincidental relationship, it doesn't have to be that way. Didn't various racing bodies change how displacement per revolution was factored when comparing Wankle rotary engines to two-stroke and four-stroke engines? What's the difference?

[@EbonyPope]

If the piston is always rotating so do the pistonrings don't they? Doesn't that mean they will never seal really effectively like in conventional engines since they cannot be broken in? I mean they never run along the same path therefore the grooves it creates will be all over the place instead of fixed position.

[@blarvinius]

Hi, can you please do videos on the MYT engine design, and the Turbocombustion design? kzbin.info/www/bejne/oHK5faCNh52NnK8si=ipxYqG9YrXGWt8Kr

[@themortz]

When A Rotary engine and a "normal" Engine love each other alot, the do a special dance and the make this:

[@driftepel]

😂

[@matsv201]

Is this why the engine oil turn white?

[@michaelmceachin1511]

@@matsv201I have never seen engine oil turn white.

[@DumbOrangeFrog]

@@michaelmceachin1511its a joke

[@patricklopes-vtec]

This is more like: when you try to make a direct drive engine inside a differential housing hehehe

[@michaelbuckers]

It's revolutionary because it revolves.

[@SuperDriver379]

This pun is underrated.

[@okoproroka1561]

So we can call it Revolver

[@BaldurGunnarsson]

@@okoproroka1561 - Or Fidel

[@kevinburke6743]

It gets around pretty well as well!

[@fredk.2001]

It is revolutionarily terrible as well.

[@wormhole331]

The whole time I was thinking "I wish I had these for my rc planes" didn't think that's what it's pretty much for.

[@koitk]

You can have it in your little RC plane, you just have to join military.

[@NeoIsrafil]

Oh yah, this would be GREAT in one of my rc aircraft... 😂

[@CreeperOnYourHouse]

It would also be great for ultralight.

[@user-xw4gr9kn8n]

A ring gear subjected to all that perpendicular stress doesn't make very good engineering sense to me. Those gear teeth are literally going to take a beating. A bearing surface they are not. For a short lived, compact unit driving a propeller, maybe. That's a lot of machining for a single use engine, though.

[@CreeperOnYourHouse]

@@user-xw4gr9kn8n 1. Yes they were designed for single use 2. Have you ever heard of a Differential?

[@thepope2412]

This is seriously one of the most educational channels on youtube

[@tuberroot1112]

If he understood the subject , it may help. If you think that, it is because you don't know enough to realise he does NOT know what he is talking about. If it gets you interested , that's great. Just be warned to check what you think you just learnt.

[@clipperwing]

I'm really curious. Could you please point out what is wrong with this video. It seems to make sense to me .

[@arne8158]

@@tuberroot1112 Why don't you give an example of what you disagree with, instead of being so vague?

[@clipperwing]

Sounds like an adhomin attack!

[@colinofay7237]

​@@tuberroot1112 could you point out what's wrong? I don't know thats why I'm asking

[@chainq68k]

"All you have to do is position your holes accordingly, and get them to match at the correct time for the correct stroke." ... Engineering is beautiful. Context is king.

[@geemy9675]

two holes in one stroke 😮

[@elios7623]

LMFAO

[@HarbisonelII]

That type of valve doesn't seem great at sealing the combustion and compression though...

[@grifon1981]

That sounds kinda... ghey

[@C.I...]

@@HarbisonelII The exhaust valves are designed for maximum scavenging.

[@mullayho1759]

Low rpm and high torque is what you need for driving a propeller, and the cilindrical shape with axial output sounds very easy to package in a drone

[@stevie-ray2020]

Plus, the gyroscopic effect mentioned earlier really benefits drone-use by stabilising the aircraft in flight!

[@tartarsauce447]

Yeah it probably can drive a prop directly without any reduction or a set of planet gears at most. And it's shape seems very aerodynamic with very small frontal area. I immediately thought of aviation use when I saw this design.

[@geemy9675]

​​@@tartarsauce447except single cylinder, 15hp...so yeah drones but not aircraft with passengers. what's the advantage compared to jet engines ? I guess noise could be a factor, you can silence the exhaust, but the propeller is always going to be noisy anyway

[@pinospin9588]

maybe good for cropduster or cheap airplane for leisure flying (replace radial engine)

[@Will-sc3hw]

@@geemy9675 cost

[@user-gd9jp7lx6c]

I admire how you explain engine balance every time again and again

[@dahlia_dazol]

In the past he has claimed that it has been explained 16 times, yet I see the count growing even more lol

[@recoilrob324]

He's a classic example of 'Tell a lie enough times and it becomes the truth'. His explanation of secondary imbalance is pure BS.

[@vapenation7061]

@@recoilrob324please elaborate?

[@nanab256]

21:54 but: -you can make this hole oval or triangle to make surface bigger, you can even extend it to the side wall of the cylinder - there is no obstructions(open valve) in the way - you are not limited by valve lift and potential collision valve and piston, it can be open longer.

[@nilnailscrew4784]

This. He literally made a rotary valve video already. Half the cylinder in a rotary valve is still more space to push air through than a full cylinder of poppet valves since the valve gets in the way.

[@igornoga5362]

While you can extend the valve in radial direction, you can't really make them much bigger in rotation direction because of valve overlap. Popet valve can also be fully open through most of the stroke, while the geometry of this valve design makes it on average half open through the stroke.

[@boam2943]

I thought the same with the addition that I would use only one hole with an external Y to select between intake and exhaust. This way you could have a full quarter hole.

[@nilnailscrew4784]

@@boam2943 I guess the downside of this is that it would induce valve float at high rpm

[@yuuji_]

Just turbo the damn thing to push more air in the cylinder ¯\_(ツ)_/¯

[@patturk7408]

Finally a tourbillon engine. Complicated enough for a watch but made for an engine....or maybe not.

[@wargamingrefugee9065]

I demand a constant force, silicon escapement watch engine! Tourbillons are too pedestrian for matters of National Security!

[@piccalillipit9211]

THATS WHAT I THOUGHT....!!! We need it on display through a window in the hood/bonnet of the car

[@berkeliumk]

And a skeletonized housing

[@Javierm0n0]

that would actually be so sick. I'd also probably be unable to afford it's inevitable 150k price xD

[@horaciokanashiro-hv2zn]

👍 see my post in the short version 😅

[@brooklynwoodard8526]

I would love to see a video about 2-stroke Detroit Diesel engines. I think they could fit well in this series, even though the concept is old. Also, keep up the great work with these videos. Your content is realistic, unlike others that are more like fairy tales.

[@trollmcclure1884]

yeah

[@user-oz5yk9bm5c]

i remember him mentioning the detroit diesel long ago in an old video

[@brooklynwoodard8526]

Do you remember which one?

[@matufujiwara7493]

i think he covered the 2 stroke diesel already in some video.

[@user-oz5yk9bm5c]

@@brooklynwoodard8526 I dont remember, sorry:/

[@morgan5630]

Dude, this is the single best video of yours I have watched, your ability to explain complex mechanical principles is FAR better than ANY of my college professors. Also, the Avanti actually, genuinely looks like a good design.

[@jacobcoughlin2408]

A reporter asked Thomas Edison if he was ever discouraged during the thousands of revisions that occurred during the creation of the light bulb. He answered "no not once, those failures were necessary. I don't think of them as failures. Instead I learned a thousand different ways to not make a light bulb" Remember that humans learn NOTHING from success. We only advance our knowledge when we fail and either physically or emotionally get hurt. Don't be afraid to fail. Be afraid to succeed without ever failing.

[@rfwillett2424]

The Motors inherent balance would be an advantage for ultra lights and para gliders. The propeller speed reduction unit being an integral part of the motor would also be advantageous and reduces weight. It also might have the potential of improved fuel efficiency, while being more reliable than two strokes. Those last two points would be debatable, have to wait and see.

[@mandrakejake]

Doubling the number of conrods, adding 3 gears and the complexity of a driven housing seems unlikely to me to benefit power to weight ratio. Rotary valve heads have never worked for long either. If this was a forced induction 2-stroke it may make more sense.

[@geemy9675]

​@@mandrakejakeyeah if rotary valves worked we would use them everywhere in 2 and 4 strokes. pressure in the cylinder ~150 at the end of compression, then ~1000psi at peak pressure. if your valve is about 1si that's like 1000lbs hammering on your rotary valve 7000times per min while it's rotating, always in the same spot + heat. poppet valves in a 4 stroke have a huge advantage. they are fixed during the whole compression and expansion phases, where the cylinder experience the highest oressure phases and pressure only improves the seal that they are making against the valve seat. rotary valves that can seal properly while not adding a ton of friction and wear....

[@mandrakejake]

@@geemy9675 I think they missed a trick not making this a piston port since the piston rotates

[@geemy9675]

@@mandrakejake not sure how a piston port could open / close the volume above the piston. in two stroke they only control transfers under the piston

[@mandrakejake]

@@geemy9675 if you're interested Google 'sleeve valve engine' - on them the barrel reciprocate but the piston doesn't. In this engine it would be reversed

[@BudgeChem]

This is an excellent video. Your closing remarks really sum up why this channel is so good imo.

[@hazardsharp3125]

He really took the right amount of time for this. Most people would have hit one point, wrote the script, and published. But here, we have the whole story, so far ...

[@scose]

"military funding" is the answer to so many "why" questions in engineering and science

[@JavierCR25]

The ICE is truly an amazing feat of engineering. Well over 100 years already and no one’s been able to truly “re invent the wheel” and make a better basic design.

[@andrewahern3730]

Otto cycle* there's tons of other practical ICE designs, most notably turbine engines.

[@JavierCR25]

@@andrewahern3730 they still remain practically unchanged after 70 years

[@super9mega]

​@@andrewahern3730I drive a Prius in one of the coolest things I know about them is they actually use the Atkins cycle, meaning the Prius is one of the only engines on the entire market that wouldn't actually benefit from a turbo. They also don't even have a real transmission either, but that's just a little bit of fun 😊

[@exothermal.sprocket]

I think opposed piston designs that require a supercharger offer a lot of potential.

[@michelarseneau9756]

Wow Thank you very much from the inventor.

[@michaelrockwell9691]

Two things to mention. One is a concern of crankshaft oiling due to centrifugal issues. The oil is definitely not going to want to hang out near the center where all the action is located. The other thing is I imagine a turbo setup should take care of the lack of power, since valve duration issues can be overcome with boost.

[@Jo-rz6bs]

If you can force oil through the crankshafts shouldn't be a bother there?

[@michelarseneau9756]

I have work very hard to fix that issue.

[@allenpaley]

@21:45 As a crude abstraction, consider that if the cylinder head could be decoupled from the cylinder itself and allow face-on-face rotation (while maintaining seal), and that if the cylinder head could be rotated with a further 2-to-1 ratio, the intake/exhaust ports could each exploit half a circle, rather than a quadrant. On second thought, that might not work because of overlap. On second second thought, overlap could be an advantage for scavenging! Perhaps it would be necessary to have two port plates in a sandwich arrangement. At the very least the ports could benefit from a surface area geometry other than circular. A 90-degree pie slice comes to mind. I love how your deep technical dives stimulate one's imagination. Keep up the great work! Additional though: Since the cylinder rotates, perhaps wall ports like a 2 stroke could be assimilated into the design. With this novel style of engine where so many rules of convention are thrown away, I think that bizarre and unorthodox concepts must be entertained.

[@hrishikeshaggrawal]

Ah yes, sacrifice the sealing in compression and combustion strokes entirely for better scavenging. No matter how many times the cylinder and piston assembly spin per every combustion rpm, because the air flow is restricted to the same face the sealing for compression and combustion stroke needs, half of the cylinder face's surface area will always be a physically present solid and only the remaining half can be made intangible for the intake and exhaust strokes. Meaning there is no point in having 4-1 gear ratios on the crank and 2 holes in the spinning cylinder head and 4 holes in the cylinder face or instead a 6-1 ratio with 3 and 6 holes respectively, because those holes will need to be smaller than the original 2-1 ratio, 1 hole, 2 hole configurations'.

[@matthewridgeway9250]

My thoughts also.

[@codymoncrief8478]

I work with a lot of machinery, and one important design flaw is the axial offset between the connecting rods on the wrist pin. When you offset, axially, two opposing forces, you get an inherent twisting action on the arms and a bending force on the pin unless there is a balancing force present. This increases stress concentrations at the corners of the bearing surfaces, increasing the probability of uneven wear. This is only worsened by speed and load. Even on components that sees fewer than ten movement cycles per day, this concentrated load quickly forces lubricants out of the critical areas and results in wiping of bushings, or localized deformation of bearing races. These things would tear themselves apart just from that alone.

[@CesarOrtiz-zl7eo]

The way you enter and explain the topic of your videos is phenomenal. You introduce it as advertised, make it seem like he best thing in the world, then proceed to explain how it is false and the reason why it is as advertised. then you explain the pros and cons. Absolutely amazing. Keep up the work my man.👍

[@F3udF1st]

First impression; Very neat, I think the form factor is the biggest potential.

[@matsv201]

Longitudinally mounted cyliders was very popular in model aircraft before electric become commonm the main benefit was that you could build a realy nice model wirh not a ugly engine stickning out

[@T3hJimmer]

@@matsv201 Thats where my mind went with this. High power to weight, small form factor, low vibration. This would be perfect for a drone with a long loiter time.

[@geemy9675]

​@@T3hJimmerhave you seen the power to weight is only good when compared to a generator..

[@itsdokko2990]

@@geemy9675 for a very light aircraft that output is hella reasonable, you don't need to have a 1:1 P/W ratio to move a drone thru the air

[@geemy9675]

@@itsdokko2990 yeah I'm just wondering the actual real life benefit vs proven engine. tech that already provide a wide range of power density if you bring down reliability/lifespan requirement to the level of rotary valves you can also make a lot of power in a small package with traditional engines

[@allenpaley]

@22:25 I think we might be overlooking the possibility of an opposed design. Consider the output shafts facing each-other axially with a differential gear set between them, and in typical differential style, a crown and pinion gear set outputting the product of the two cylinders' work.

[@zorktxandnand3774]

Well then you have the output shaft where you also need to put your in port and exhaust port + spark plug, so you have a space issue.

[@1man1guitarletsgo]

@@zorktxandnand3774 No, the spark plugs and ports would be at the other end. The output shaft is underneath the big fixed gear when the cylinder's vertical, so an opposed design would work. It would be interesting to see a BMW motorbike with this engine.

[@hrishikeshaggrawal]

Oh god

[@MikeJones-wp2mw]

Dude they could totally make a boxer engine out of this. Even just the dual rod opposed crank weights idea could be used without the rotating cylinder to get some insane performance. I bet that in a bike engine could easily hit some insane rpms.

[@AndrewBrenner1]

I can see that any number of boxers could be opposed in a radial configuration. Presuming that they can fit into pi. However, increasing the number of calendars would require a larger and larger diameter for the final drive. I suppose it also changes the slender single cylinder into a fat circle of ladies dancing.

[@MotoRideswJohn]

The irony of my learning about these fascinating internal combustion engines, during a time in which electric drivetrains are the hot topic, is not lost on me.

[@adrianschmidt5564]

electric drivetrains are so much more simpler. I know that ICE fuels have more energy density than batteries, which is important for aviation, but for anything ground based electric is the only answer in the near future.

[@Galfrid]

Electric has it's own set of issues. Hardly the "only" answer for the future

[@williammurray4584]

Your ability to explain engineering principles is superlative. You should have a series of all your favorite videos put on “The Great Courses” library. You are like the Neil Degrasse Tyson of engineering and gearheads! Please always make these videos!! They are amazing!

[@0N3T1tan]

You are a great teacher! I don't think I ever would understand this stuff without you.

[@popodori]

as always, an excellent review. simply amazing that we get this every time

[@BillHimmel]

What a clever and beautiful design! Don't know if it is practical, but thank everybody involved for trying!

[@MrShwaggins]

You just earned my sub by explaining gear ratios in a way I understood instantly. I honestly could never wrap my head around gearing outside of what it looks like/type but you opened up another line of thoughtfulness with showing it as a lever. I don't know why I never made that connection before. Thank you.

[@daniel.s.stefanov]

"All you have to do is position your holes accordingly" I'm saving this to show my wife.

[@OutsideTheTargetDemographic]

It's output is weak, but it's also smaller and lighter than others. 😅😂

[@daniel.s.stefanov]

@@OutsideTheTargetDemographic Aw god damn this video's a gold mine 😂

[@Bart-nm9jn]

69 likes as I'm seeing this!!! I can't add another. Forgive me please lol

[@user-hu2iw5qu3i]

They already have the rotating sleeve cyllinder. Now they have to learn about Knight, Bristol and Napier engines and they can hone in on the formula. Multiples are possible as a single cyllinder dual piston a.k.a. Jumo layout, just with inline outputs.

[@GodmanchesterGoblin]

Napier Deltic? 36 pistons in 18 cylinders with 3 crank shafts, job done!

[@stephenwestlake7164]

@@GodmanchesterGoblin Napier Sabre. 37litre 24 cyl H sleeve valve

[@GodmanchesterGoblin]

@@stephenwestlake7164 That'll do nicely!

[@lqr824]

0:02 "This engine is revolutionary!" he exclaims, as the engine completes a revolution.

[@michelhadid]

Thanks for this video. The work behind it, editing and animations are insane!

[@imweirdimnotsocial]

Thank you for the analysis! It was a very pleasant video!

[@Bapate-rh9be]

16:00 Not sure: The rocking couple acts on the gears which acts on the large spur gear, and the rocking motion will always interact with the same teeth on both gears. Pretty sure you can tell the additional wear after a while.

[@stevie-ray2020]

True, but negligible for drone-use!

[@Bapate-rh9be]

@@stevie-ray2020 Yes, that is true.

[@geemy9675]

​@@stevie-ray2020this revolutionary engine is only good for army because it costs 100x the price and lasts 1/1000 the lifespan.

[@erkinalp]

Yeah, the differential geartrain is the main wear item there.

[@hrishikeshaggrawal]

@@geemy9675 Its also smaller and thus lighter, meaning more of the entire engine volume is dedicated to the combustion volume.

[@aw9680]

The most important part of the video is the last 2 minutes. It's beneficial because we can learn something.

[@technopong]

I love your engine design deep dives, novel or otherwise. Keep up the good work!

[@senatorchinchilla5389]

As usual with these weird concepts, I need it. My engineering brain is tickled. Edit: I just noticed the crank pins are in single shear, whoooo boy.

[@PapaWheelie1]

Good catch- another reason they are suited for one way drones

[@Jo-rz6bs]

Some compressors do it, but Owp.

[@WolfmanDude]

Older single cylinder 2 stroke engines did this all the time. Its not a discrete pin you can take out, the "pin" is one part with the crankshaft. It worked really well in the 1950s, this will be trivial with modern materials and design.

[@SouseMouse]

Now consider the loads on the wrist pin- the cranks are opposed, but off-axis, so they're imparting a rotational force on the piston. What constrains that? The wrist pin. Those conrod holes will go to hell in a hurry.

[@xtnuser5338]

I think there is some internal thing not shown in the animated 3D views. That must be the case. Otherwise those ends of the crank pins aren't even positively located. I mean, the way it's shown in the video, they aren't constrained by anything at all, and when the piston goes up and down they would just flop all over the place. Also notice that the main output shaft isn't connected to anything. The two crank pins must be attached to each other in the middle. Not by just being a continuous shaft though, because of course they need to rotate in opposite directions. Put thrust bearings at the output shaft penetration of the case, let the output shaft continue upwards a bit past those two crank pins, seat the end of each crank pin in a small bore on the side of that output shaft with an appropriate bearing. Or SOME arrangement that is functionally similar to that. Like maybe the output shaft stops short of those pins, and all three are connected with some sort of cast "T" item that's keyed or splined to the output shaft. Whatever, anything that functions that way. Bingo, the crank pins are in double shear, AND they drive the output shaft.

[@tommybronze3451]

One thing that is SERIOUSLY under appreciated by bystanders in aviation is amount of the vibration that engine makes. More vibration = bulkier air frame, and as much you can make engine light as a feather, if you need pig iron braces to hold it in place for the plane not to shake apart - it's not worth it. I understand where they were going with this one, they can have a very light weight frame that this bolts on and have more or less "trust" load.

[@bowieinc]

I’m so glad you made this. I’ve been really curious about it.

[@evanarnold580]

Well done! This is a fantastic explanation of the MA-250. I had the opportunity to consult for Avadi and built the first run stand stateside for it. Running the engine is so fascinating.

[@Drunken_Hamster]

I still think it's advantageous and has plenty of potential. If they let David Vizard manage their cylinder head, combustion chamber, port, and timing design, it could make substantially more power and torque than it currently does while retaining the other benefits. I'd love to see a boxer twin or cross-plane boxer 4 version of this (with DV's help) in the 800-1200cc range on a motorcycle or small airplane. *EDIT:* Okay, so technically speaking "all of the bore area for breathing" is a misnomer. Even with 4 and 5-valve heads, only 60% of the actual area is taken up with poppet valves. This is an inherent flaw with poppet valves, but the Avadi engine doesn't use them, it has ports, instead, which can be sized larger than they currently are. Hence why I said to let David Vizard take over the head design. There's definitely enough space to get the same valve area as conventional 2-valve heads, which, given the velocity improvements at low RPM and the magic that David Vizard works on a regular basis, is more than adequate for even a 10,000 RPM engine, let alone the mere 7000 this uses. *EDIT2:* And another thing, isn't the "practical single cylinder displacement limit" all due to balance and vibration? If this solves all of that, wouldn't the practical limit go up to 1200-1500cc, which is reflective of big block V8s?

[@hrishikeshaggrawal]

The practical limit of a single cylinder's displacement has a different bottle neck, which is the piston seals. The volume increases by a factor of cubes but the lining of the seals increases linearly with cylinder size, some extra gains could be claimed with an oversquare design but you get the idea. The problem isn't balance, you usually wouldn't see cylinders above 800cc in even any multi-cylinder engine either, unless you consider the engines for industrial ships and subs but those use much thicker and multiple seals, or such is what I'm guessing.

[@ABaumstumpf]

"Even with 4 and 5-valve heads, only 60% of the actual area is taken up with poppet valves." More would be possible but using circular valves is just the best option overall. "which can be sized larger than they currently are" Not really. Changing their geometry directly affects timings. Making a port larger means that it is open earlier or closes later. And it also has another even bigger problem: they are ports. They simply can not open or close, so instead of a valve opening to fully open and then staying open you have a port that slowly opens and closes gradually (slowly only in comparison). To get an inlet that is open just for say the intake-stroke the port can only cover 1/8th the area. "There's definitely enough space to get the same valve area as conventional 2-valve heads" So no, it can not come even close to that. But it gets worse: As it gradually opens and closes it would on average only be 1/16th the area of the cylinderhead.

[@robertescalante9858]

I see huge potential for this engine as a 1.0 to have some form of forced induction. That would hugely help the airflow through the intake. I'm not sure of any system off the top of my head (aside turbos and superchargers) that would help bring the air into the cylinder, maybe something like a 2 stroke setup is coming? awesome video man

[@yorosel3206]

Exactly what I was thinking!

[@jaspernatchez]

I find your videos so fascinating and I'm not even much into cars/engines. Thank you!

[@brent3569]

I always learn something new from your videos. Thanks for making them and explaining the topics so well.

[@paulohenriquesilvaalves6781]

I was thinking about this engine concept yesterday. What a coincidence! 😅

[@hfyaer]

Happens to me all the time lol

[@Texmotodad]

Did I miss it? I did not see how the "crank" is connected to an output shaft. A BIG thank you for continuing to show us these alternate engines.

[@RadioReprised]

The rotating cylinder is tied to the output shaft.

[@coreobroomstick2739]

@@RadioReprised Exactly.... how? Does the piston turn the cylinder? In the animations, it looks like the output shaft is just magically connected down by the crank somehow. It doesn't really make sense.

[@coreobroomstick2739]

It looks like the crank bevel gears are mounted inside a yoke, sort of like a car differential. The whole yoke/cylinder hybrid assembly rotates on a shaft, which is the output shaft of the engine. At 0:38 you can see some little stub shafts sticking out of the bevel gears. I think these shafts connect them to the yoke. At 1:06 you can see this, it's just hard to determine what is cutaway for demonstration vs. what actually needs to be there for functionality.

[@jamesshearer9616]

One of the best explanations of Anything I have ever seen. Great Job!

[@DesyncX]

Thank you for the great explanation! It's always super interesting to learn a bit more about engine design :)

[@pmcKANE]

Revolutionary engine... pretty sure that most of them revolutionary in at least one regard :3

[@PeteOfDarkness]

New ways of making working design more complicated.

[@declanneary9725]

love your stuff man

[@deslomator]

The last four minutes of this video deserve a longer followup, it was really interesting to see the engineering in its context.

[@mrwhips3623]

These quirky engines literally never go anywhere

[@ludwigreiser4053]

Thanks a lot for the very interesting an critical analysis of this engine design! And thanks a lot for the motivation to create own engine designs - I will immediately start! 😁👍🍀

[@WilliamDye-willdye]

Best wishes on the new engine design

[@ludwigreiser4053]

@@WilliamDye-willdye Thanks! 😅 I will inform you about any progress! 😂

[@luigifranceschi2350]

I disagree on the part that because of higher RPM is more expensive to do it. The engine has no traditional valves, with camshaft and springs. So it can easily run higher RPM because the role of the valves is done but the rotating head, which is much simpler and rotates exactly at the speed of the piston without any possibility of delay or damaging the valves due to overspeeding the camshaft.

[@sicat2345]

nah, it cant do high rpm cuz of the relatively smol portholes. Cant breathe in and out fast enough.

[@luigifranceschi2350]

@@sicat2345 but the same you have on wankel. And they still rev up pretty high. Don’t forget that you can still use in theory up to 1/4 of the surface for intake or exhaust. Which is quite a lot.

[@larsjrgensen5975]

@@luigifranceschi2350 You have a max RPM because the entire engine is also spinning creating a massive rotating mass that wants to rip itself apart. The common tube for intake and exhaust has air in it that needs to stop flowing one way and start flowing the other way 7000 times a minute, so at relatively low RPM the engine is going to stop getting fresh air into the combustion chamber, because it needs to change direction all the time. In a wankel or normal piston engine the air only needs to go from stop to full speed, not full speed to stop to full speed reverse. There is also going to be a port full of exhaust air left in the tube, that needs to be sucked back into the cylinder before fresh air can be sucked into the cylinder, on top of the small portholes problem Sicat2345 also mentions.

[@elsullo2]

@@larsjrgensen5975 "the entire engine is also spinning" Huh?............................elsullo

[@larsjrgensen5975]

@@elsullo2 The crank, piston, cylinder, cylinder head and cooling fins on the cylinder is all spinning around. A outer casing is put around all the spinning things to make it possible to mount the engine to something.

[@kstoneace]

I very much enjoy and appreciate your channel. You have fascinating subjects, and are able to explain so that i can understand. Thank you!

[@hasanimam3102]

23:13 I was thinking about Drones from the very beginning of the video, the moment when you said DRONES; I felt like I won the lottery 😂

[@vintagespeedshop]

Just one thought. You point out that the Avadi is restricted compared to a conventional engine because you can only use half the cylinder head for ports. Surly the fact the Avadi engine has no valves restricting the port flow and the ports can be made straight, wouldent the Avadi have better flow through 2 ports than a conventional engine with 4 valves?

[@paulqueripel3493]

Do the ports have to be round? Can't they be more wedge shaped, narrower by the plug, wider on the outside?

[@hrishikeshaggrawal]

No matter how you try to change the shape of the holes or their number or the crown-crank gear ratio, having MORE than half the cylinder head's surface area dedicated to intake and exhaust GAURANTEES you sacrifice compression ratio or the sealing in the combustion stroke, which are FAR more important than intake scavenging gains.

[@michelarseneau9756]

When I start designing this engine with friends (we were all working with a F1 engine manufacturer) I can't name it but we had the same visions and yes because the opening have no valve obstructing the ways it become obvious with calculations that even with the opening of a smaller holes it gets enough breading to this engine to perform well at those speed.

[@lake258]

Well it does revolute alright.

[@complicatedscene7484]

love your channel, every vid is fascinating. Thank you!

[@markchapman2585]

Such a awesome channel. I am pretty good with cars. But you break it down for people to understand. I never heard of this engine. Thanks for breaking it down.

[@krakhedd]

I'm proud that I'm only about halfway through my 2nd mug of Sunday morning coffee yet still knew the 2:1 thing was gonna be the camshaft, which means it's probably more simple of an answer than I'm giving myself credit for! ;p

[@IGMWN]

Many of your videos are pretty accurate, but this is another one that I have some issues with. The biggest issues I have is at around 19:30 when you are explaining that the output at the crankshaft is not the output at the crankshaft because the engine uses gears for timing instead of gears and a chain for timing. This engine will have a power stroke every revolution on the crankshaft vs a conventional single piston engine having a power stroke every two rotations of the crankshaft, however, the power stroke for this engine will only be effective for about 90° of rotation vs a conventional single piston engine at about 180 degrees of rotation. This engine will fire twice in 720° of rotation on the crankshaft for about 180 degrees of power output every 720° of rotation making the comparison between the two engines very similar.

[@jacquesolivier65]

As always: Crystal clear explanations ! Congrats…

[@danvasii9884]

Thanks again for your wonderful explanations! I really appreciate your videos!

[@jfdd43]

Seems like a more complicated version of the ‘one stroke’ engine that you covered a few months ago. All these new engines are exciting. I wish we’d start seeing them in vehicles

[@avyfa1946]

Honestly, Liquid Piston engine still seems like the best choice for drones, especially export-oriented and suicide ones. Low amount of moving parts, powerful enough, looks a lot more rebuildable than Avadi and Spanish one, can run on practically anything and have low noise and vibration.

[@michelarseneau9756]

Liquide Piston is in bankruptcy even with multi million financing!

[@cephyr13]

Great video. I think I have a way to use the Avadi for cars. If Avadi scales to 800cc, and puts one motor at each wheel, the car would have 240 combined hp at ~7500 RPM. Either fix the engine to each wheel so it turns with the wheel (probably not the best idea) or put a CV axle between each motor and wheel bearing. What's nice about that design is that when 1,2, or 3 motors break, you can keep driving. Motor removal for repair would also be cheap and easy. Weight distribution would be excellent with a very low center of gravity. It's like lowering a contemporary engine and spreading its weight to each corner. If you were to combine it with the comprex exhaust to electric supercharger system, you could dramatically increase hp & tq outputs, especially at low RPM, and it would be virtually instant power and super-efficient. That would make for a lightweight, efficient, balanced sports car.

[@Jonbob836]

really enjoyed this! loved the detailed explanation!

[@maikeru01]

I though he opened the video with "what is up shit heads?"

[@stefanschuchardt5734]

He does. So then, what is up, shit heads?

[@stefanschuchardt5734]

He does. So then, what is up, shit heads?

[@horsethi3f]

Can someone just invent a bog standard inline 4 that lasts a million miles.

[@kevwills858]

I'm on your side 😄👍

[@d4a]

Toyota did, like 20+ years ago. Some other manufacturers too.

[@martin-vv9lf]

and volvo did. I drove a 4cyl perkins diesel in a mf165 based industrial loader past that. had the crankshaft reconditioned 3 times. it's not that they can't build them, it's illegal to build them. you can drive an electric car past that legally though.

[@danielkiss7003]

Mercedes had a few diesel engines like that

[@spdaltid]

Amazing creation, and even better explanation.

[@davebancroft]

In WW2 some engines were made with a service life of just a few hours. Landing craft, for example. Line bored bored crankcases, with no main bearings. My dad's company, Ruston Hornsby, started receiving letters, often in pingin English, from around the world requesting new parts to rebuild them. They developed a kit that could be retrofitted; a new crank with smaller journals and a matching set of main bearings :-) some

[@shies7967]

wow an engine with literally no upsides while being way worse in literally everything!!! great design!!!

[@ferrumignis]

It absolutely does have upsides; nearly perfect balance from a single cylinder and no net piston thrust. However it has many more downsides.

[@michaelbrinks8089]

Piston rings either spinning or stationary in the ring grooves, while also moving up & down. Both at high rates of speed = Possibly more ring/cylinder wear ? More possible chance of break down?

[@shangrilaladeda]

Most companies like things breaking down after warranty

[@Erowens98]

​​@@michaelbrinks8089 The cylinder is also rotating so it shouldn't increase wear in that regard. The advantage of this engine is how light and compact it is. Making it suitable for small scale aviation applications.

[@d4a]

Wow!! A comment that makes it obvious you didn't watch 10% of the video and contributed nothing useful. Great comment.

[@mhh3]

already looks heavy and friction rich

[@montreauxs]

No it doesn't.. Not at all. (Think McFly..... think..)

[@brizlor]

The simplicity of the valve train opens up the possibility of apposed pistons rather than inline 4 as you suggest

[@diogenedigionaakagiuseppe8676]

As always thank you, really well done and interesting stuff. To mention one, I really liked the videos about turbofan and turbojet engines, a masterpiece. I really appreciated the tesla drive test video you did recently. I agree 100% with every word and reaction you spent on it. Great job, great great great channel.

[@shriramvenu]

you could scale the Avadi to a 2 cylinder engine if you put them in a boxer alignment

[@ARKTech49]

One crank will rotate clockwise and other will rotate in counter clockwise if it's in a boxer orientation. Dont know if it will work out.

[@stephenwestlake7164]

But then you would need more gears to get to the output shaft.

[@Sir_Cactus]

Wear and tear is going to be an issue. The gear ration of 2:1 is kinda problematic, as it means the gear teeth only ever engage with certain teeth on the other gear. This results in the gear teeth not wearing down evenly. To make matters worse, the rocking couple created by the two counterweights acts directly onto the gears, making the gears wear down even faster. I know there are engines with gear driven camshafts, yet these have intermediate gears which do not have a number of teeth at is a multiple of the number of teeth of either gear they engage with.

[@montreauxs]

Nope... Nice try though.

[@user-pg9jg2xe4n]

Great video as always!

[@ChristiaanNdoro]

A well done video - I thought I would be fast forwarding a lot because the video is so long, but its actually very information dense and I actually had to rewind at some points

[@Badge1122]

Stupid idea, too much weight and expensive gears. Has anyone though about the piston is being twisted, rods coming from different angle. Piston pin in the rods won't last lone. Do not want one no matter WHAT.

[@guidodebacker4205]

thanks for covering this elegant design

[@stger2384]

Thanks! We're probably all waiting for the next otto / diesel / wankel even..

[@TheRed6263]

Again an exceptional analysis of this tech and its true targeted application.

[@davidheylen2452]

This was an amazing video. Interesting topic? Check. Thorough and intelligent analysis? Check. Clear, easy to understand explanations and illustrations? Check. Fun to watch? Check. Nutritious AND delicious! Keep up the first class work.

[@Eteroklitos83]

Thanks for (again) one of the most educational videos on youtube. Cheers :)

[@philipershler420]

This is an absolutely wonderful discussion about a very odd concept. Thank You!

[@azrobbins01]

Love your channel, man!

[@louisfkoorts5590]

Very interesting and insightful. Thank you. Glad this ended up in my feed. Since I am new here, I will search for anything on the Neander Diesel, over here. 👍🏻🌿

[@extra-dry]

You must be these engineering firms, worst nightmare. Nothing gets past you. Good work😂

[@paulfaulkner6299]

Masterful explanation once more. Thank you

[@A2J_Tim]

thank you for your content, I love this kind of stuff.

[@mrbarthabarna]

A really deep, useful, exciting and informative content again about something new in the world for mechanic-lovers, as You say; Engineheads! ❤👌

[@aalborgfantasy]

The way you explain it... You are awesome...

[@jannek5757]

That connection to drones, very good thinking, I did not see that coming but it is very obvious now, that I know it :)

[@talinpeacy7222]

The valve is directly connected to the drive train and rotates with the piston. You could theoretically stack them vertically into a really long, cylindrical inline infinity. Also, the high RPMs, good stability, and the ability to add a similar air intake and exhaust valve on the side of the rotating combustion chamber might also make for a fairly effective turbo/super charger.

[@paulbriggs3072]

Absolutely IDEAL for an outboard motor with a vertical shaft. Lightweight also. Smooth.

[@awildted3265]

Really enjoyed the video!

[@9785633425657]

Thank you for the great analysis!