The Scotch Yoke Engine is Alive! 8 Pistons, 4 Rods

A video that can help you better understand engine balance and the difference between flat boxer and flat non-boxer engines: • Deep Dive: Inline 4 vs...
Last week I made a video explaining scotch yoke engines and I did a bit of an update on Alfadan, the company that is planning to release a scotch yoke inline four engine in the future.
But after making the video I was still thinking a bit about the scotch yoke design and it’s related balance so I decided to do some research. Now on the Wikipedia page for scotch yoke I found this interesting chunk of text that mentions the Bourke engine as well hot air and steam engines, that’s all pretty well known stuff. But what I never heard about before is this, something called the sytech engine. And as you can see this is not hyperlinked…there’s no wiki page on sytech engine.
So I google sytech engine and eventually ended up on this page right here, and boy was I surprised. Look! This is not a 3d render. This is a photo of an actual engine. This thing is real. And it’s incredibly interesting. Now before we go any further, I just want to say that this is not in any way a sponsored video. I have not even gotten in touch with this company. I’m not promoting anything. This is just me exploring and sharing something really really interesting that I found purely by chance. And as you will see I didn't need to get in touch with these guys because all the information you could possibly want, they have already published it, they have done all the testing, this is pretty much a production ready engine. Honestly this whole page really made my day as it’s been a long time that I stumbled onto something this new and this interesting. Look, they even made a flat 8-cylinder non-boxer scotch yoke engine
And as you can see the engine in this video is a scotch yoke flat four non-boxer opposed piston engine, which interestingly enough is a completely different approach to Alfadan which aims to make a inline four scotch yoke engine.
Now this is extremely interesting because a flat four non-boxer engine is a stupid idea from the perspective of engine balance. Now as you have seen from my previous video the scotch yoke design completely eliminates secondary balance issues which means that a four cylinder now becomes the lowest number of cylinder needed to achieve perfect balance without balance shafts, whereas with a conventional crank and rod the lowest number of cylinders needed to achieve this is 6.
A scotch yoke inline four has perfect primary and secondary balance. But a flat four non-boxer does not, regardless if it’s scotch yoke or not.
The four cylinder scotch yoke engine is supposed to be a range extender and when you take this into account the flat four non-boxer configuration really starts making sense because this is overall the most compact possible four cylinder engine configuration.
And if we scroll down to the bottom of the website we can find three very interesting PDFs. If we open the first one we will find an incredible wealth of data among which is also this page. And here you can see that a very compact flat four engine enables placement almost anywhere in the car or in the words of sytech “the engine can be placed in areas of the vehicle that other engines cannot”.
As you can see a flat four scotch yoke beats other four cylinders in terms of size. In the boxer each rod gets its own crankpin but in the flat engine we put two rods on one crank pin. This is why a flat non-boxer engine is noticeably shorter than a flat boxer engine. But the scotch yoke design takes this a step further. In conventional flat non boxer we have to stack the rods side by side but in a scotch yoke the engine is constructed in such a way that the pistons are perfectly opposed which means that a scotch yoke flat four can be shorter than any conventional four cylinder engine configuration.
Another interesting thing to observe Is that this is a modular engine. According to this Sytech is planning to offer a 2 a 4 and an 8 cylinder version. Modularity means high parts commonality and this means reduced costs and increased market coverage. The 2 cylinder version can for example be used for home generators, the four cylinder is a great range extender whereas the 8 cylinder is likely intended for performance oriented combustion only or hybrid vehicles. I have to say that the 8 cylinder is extremely interesting as this is a true engine-head configuration. I’m pretty sure they went for 8 cylinders because this configuration enables perfect balance out of the box without balancing shafts. Judging from the engine codes the 8 cylinder is a 3.0 liter engine and in turbocharged form it churns out 335 horsepower which isn’t especially impressive by modern standards but it’s still definitely respectable.
A special thank you to my patrons:
Daniel
Pepe
Brian Alvarez
Peter Della Flora
Dave Westwood
Joe C
Zwoa Meda Beda
Toma Marini
Cole Philips
#d4a #scotchyoke

[@inertiaMS]

Some times people need to relax their expectation of every idea needing to become a commercial success to be considered anything but a failure or scam. Whether it becomes a relavant piece of technology going forward we should all just enjoy this process or seeing and working through this engineering challenges

[@d4a]

Thank you for that!

[@piccalillipit9211]

I completely agree

[@kricker8562]

@@d4a I was wondering, if the scotch yoke is allowed to tilt by using a wrist pin, how is it then any different to a normal engine with con-rods?

[@GCS88]

@@kricker8562 It's all about the pull, a traditional piston on conrods gets pulled on an angle so 'side thrusts' occurs when the rings glide on the cylinder walls, I can imagine that the scotch yoke would also have this but in a very miniscule amount as it moves in a vertical manner

[@geemy9675]

​​​​@@kricker8562hink the Conrod is guided and actually not supposed to rotate more than within the tolerances. the pin is just to spread the side load and friction of the piston on all the contact surface with the cylinder instead of just the edge. think a hundredth of a degree of rotation if the Conrod is free to rotate then you have one to many degree of freedom and no more direct relation between the pistons position and crank position. the crank could rotate without moving the piston! the engine won't spin predictably, you don't have accurate timing and an engine that wouldn't even start and would lock itself

[@thevoiceofcake]

Huge props to the company for posting their data.

[@Taliyon]

I've studied engine balance for over a decade. You consistently break it down in a way I've never been able to translate to others.

[@user-ec9bs4df1q]

What did you study? These engines are a balance nightmare. If you were that knowledgeable you would know how much bs this guy spits out

[@Wtfinc]

@@user-ec9bs4df1qhe just says he studied it, not went to school. U need to calm down. And dude explained it great, there was no BS. If you anything about anything you would not have latched onto that. Since you know everything, why does he keep clarifying the flat 4 as “non-boxer” when a boxer engine is just a Subaru flat 4, its not an engine type. If it is, what makes a boxer different from any other flat 4? Different ignition cycles? Idk

[@kadmow]

@@Wtfinc : Boxer engine - also typical of Porsche 911 (Boxter, Cayman, Spyder) flat engines (aero derived) - typified by offset cylinders with conrods on individual crankshaft journals - moving with with opposing directions (matched pairs moving out or inwards simultaneously - Apparently it is a very old design, from back in 1887 (Karl Benz), long before Ferdinand became chief automaker to Herr H. Commonly adopted in Aircraft applications - ie. Lycoming, Continental, etc.. Other flat 4's use common journals and evenly-opposed cylinders - both cylinders motion being constrained by the common crank journal.. (as per the graphics in this video) - the Flat "non-boxer" is commonly described as a 180 degree 'V' engine - any angle could be used for packaging needs (Ferrari flat 12 is an example (used in the Berlinetta Boxer, which funny enough didn't have a Boxer Engine).. - note; flat plane and cross plane cranks could be used in either v or flat engines - as well as individual or shared journals, there may not be a pet name for every variant, Boxer is just one which stuck. NB, all of this could well be wrong, do your own research, it is fairly easy these days, lol...

[@colinfitzsimons3409]

​@@Wtfinc is that comment for real? What a joke!

[@colinfitzsimons3409]

​@@Wtfinc the "dude" got it completely wrong yet again.

[@myhandleurl]

Thank you. As someone who had to leave behind mechanical engineering to pursue IT, your amazing channel helps me stay up to date with the field I truly love.

[@shampoo4273]

Same lol

[@alphaforce6998]

What is it with people not being able to accept responsibility for the decisions they make. Who put a gun to your head or otherwise coerced you into choosing IT, where you will soon be replaced by an AI chatbot, instead of sticking with the thing you enjoyed?

[@myhandleurl]

@@alphaforce6998 No one put a gun to my head. I chose IT bcos it provides a good income and the demand for mechanical engineerings in auto industry is dropping (at least in my part of the world). Sometimes one can’t always follow their passion. I have to also say, IT is not as boring as I assumed it might be.

[@alphaforce6998]

@@myhandleurl If you are a decent mechanical engineer, what is stopping you from independently applying your skills to design and sell things OR plans for other people to build things?

[@artlewellan2294]

@@myhandleurl A flaw in the presentation of this engine type may be a lack of thorough analysis of its "extended range" plug-in hybrid (PHEV) applications. PHEV engines achieve highest fuel economy (100mpg -150mpg) when their modest battery packs (Prius 5kwh vs Chevy Volt 18kwh) drive the car while the ICEngine is off. The ICEngine of a PHEV drivetrain is designed for fuel economy, not maximum horsepower nor torque. There are many, many benefits PHEV tech offers that deserve mention more than how their ICEngines achieve fantastic fuel economy. Another benefit is public safety. PHEVs can be driven by reckless speeders but their fuel economy plummets from 100-150mpg to 40-50mpg. Keeping a light touch on the gas pedal can teach idiot motorists how to drive defensively while spending less on gas. While BEV & HFCEV tech emphasize maximum driving range (say 300 miles) the limited all-electric range PHEVs offer (20-50 miles) encourages shorter drives which supports local economies whereby more trips eventually become possible without having to drive.

[@markm0000]

This guy has unlocked the ability to love engines more than most guys love women.

[@d4a]

😂😂😂

[@BloodyMobile]

Only a true engineer can properly admire engineering achievements. Most things aren't impressive unless you understand /why/ they /are/ impressive. The best example are CPUs. What our phones can do in the size and energy footprint today, would've been a borderline mini (not just in the literal sense) super-computer a quarter century ago. Back when CPU speeds were 3 digit *mega*hertz and some computers even had a "Turbo" key, which is basically the ancestor of on-demand overclocking. Today CPUs do that constantly on their own, because why run at 2.5 Ghz when there's nothing to do? Literal waste of power. Same goes for engines. The engineering to get them as efficient as they are today went equally far, but you need to understand how intricate the balance of all parts in relation to each other is, before it becomes truly impressive. An example here would by my '18 VW Polo vs an original VW Beetle: the Beetle needs 3x the fuel of my Polo to create 1/3 of the power. My Polo can go +180 km/h with the consumption that the Beetle had on *average*. If that progression over the decades isn't impressive, then nothing in the engineering world is. Probably. But it's not impressive unless one really builds an understanding for the "how" and "why" of these examples. Without that, it's just numbers.

[@VintageSG]

Cars don't get jealous if you look at another car. Cars don't stab you if you take another for a test drive. Cars don't care if you're polycarous ( polygamy with cars? ) Own two cars?, sleep well. Cars don't care if you replace them with a younger, slimmer model. Cars don't take your house and savings if you get another one. Cars don't gossip if you take a motorbike for a ride. Cars shut up when you turn them off and walk away. Cars are easy to turn on when you want. Cars don't care if you fart. Cars don't have psycho mothers.

[@toejamr1]

Yes. We call this autism

[@OldSchoolZ-wy2yx]

​@@toejamr1 wtf are you on

[@eTiMaGo]

Looks like it could drop into a Subaru :D

[@Athiril]

Yeah I think a scotch yoke boxer would be pretty cool. We might as well go all the way. Dimpled pistons. Some kind of freevalve for full timing control.

[@mikewallace8087]

@@Athiril the problem with all these I.C.E. is they are energy sinks that reject energy to the surrounding air . No ceramic engine revolution yet.

[@Vel1ar]

@@Athiril well, 4cyl seems to peak in power at 4500 rpm, which is disappointing. If 8cyl redlines in same rpm range, it'll be one boring-ass engine.

[@budthecyborg4575]

My first thought. I would cry tears of joy if this can revive the WRX STI.

[@2b134]

@@Vel1ar yeah, but I assume that might be due to the efficiency-oriented cam profile, maybe with a more aggressive profile it could be much better at higher rpm

[@alfadanhighperformanceoutb8416]

At ALFADAN we looked at this same design given that the owner personally owned the only Bourke 400 ever built. The Bourke 400 was this same flat 4 design but in a two stroke, 400 cubic inch version. The ALFADAN outboard project required a 7.5 Liter displacement and the i4 was the best platform that gave us the smallest engine possible. Although our design ideas originated from the Scotch Yoke we had to take a completely different design approach due the weak lower end of the rod as described in this video. In summary, the ALFADAN design achieves large displacement in a small engine package operating under perfect primary and secondary balance without the added friction and complexity of balance shafts. Great video D4A!

[@rickcollins1825]

Why couldn't ALFADAN strengthen the bottom of the Scotch Yoke? It's only loaded on the intake stroke of the cycle.

[@FarhadB-og9js]

این پروژه هم شکست خورده هست. بیخود تلاش نکنید

[@horrorhotel1999]

This commercial brought to you by investor-money which was meant to go towards developing the final product, but goes to PR-salaries instead ❤

[@albertaraujo6358]

We have no affiliation or business with D4A. Nevertheless, D4A has done a great job at describing the SY engine. With regards to strengthening the bottom of the SY rod it does not solve the problem. As weight increases in trying to add strength, the reciprocating mass also increases which further increases the load on the rod and bearing. We worked on this design and decided to opt for a new design with no lower rod end and therefore solved this issue.

[@shootadeah]

Dude your videos are LITERALLY the most detailed and informative videos on KZbin!! And you’re the only one who can keep me completely attentive even with A.D.D. 🤣😂

[@apparentlysmarterthanyou3446]

I hear you about the ADD, something makes me think that this guy suffers from a neurodivergence himself. Not always a bad thing,unlike what people think! Besides, having ADD, if we like a subject we will focus on it intensely, normally its only a hinderance if you're trying to focus on something you dont like but need to do XD

[@maccaberry1041]

The grin on your face shows how excited your are and is so fun to watch. The ICE is not dead, and your enthusiasm for it brings a smile to my face too. I bet when you discovered this, it even exceeded the joy of your first motorcycle ride.

[@johnburns4017]

The ICE is slowly dying. The end will be quick.

[@cerseonbrassmann5222]

I just love your expressions. you actually really glow up/ geek out over it. it's fascinating

[@der_kanadier]

I think you might have missed an aspect of the cylinder wall forces @12:30. In the boxer configuration, the piston leaning force during the compression stroke is shared with the non-combustion cylinder through the single connecting rod. This should roughly half the twisting load between the cylinders and spread the wear from this friction to both sides of the cylinder. This could reduce overall wear due to these forces. Great video!

[@raptorjesus5488]

I don't know how the i4 will solve yoke lean all I can think of is guides in the block on either side of the big end of the yoke or a guide rod on the yoke sticking into the oil pan through a girdle or something

[@rickcollins1825]

Yes, the Scotch Yoke as show in the video would not only create friction on the piston skirt and cylinder walls, it creates a twisting motion on the piston, since there is nothing else to keep the piston straight. By adding a wrist pin, the twisting force is eliminated, leaving only the sideways push from the offset force of the crank bearing.

[@JeffreyClark-fp5up]

I am a private pilot that owns a single opposing piston engine airplane in a land configuration, My airplane is a 1949 North American, Ryan Navion which is powered by a Teledyne Continental E-225-4 over head valve opposing 6 cylinder engine with a 5in bore and a 4in stroke, which means that this engine is not a boxer. This engine has 470 cubic in displacement and gives 225 HP at 2,600 RPM. The engine in my airplane works well and is proven dependable after decades or application. The continental engine company has the only engine that has a 8 cylinder version of this design, which supply's an impressive 400 HP and to my knowledge is only in one airplane and that is a Piper Comanche 400. All that being said, this Scotch Yoke engine would be a great engine for the aviation industry. I would love to see this happen. So thank you for your video and update on a modern tech improvement in my opinion.

[@foolicooli]

A 3.0L puting out 335 is pretty good for what is essentially a experimental design.

[@didjterminator808]

ikr!? and with how small and light it is you could probably fit it into many cars that shouldn't be able to fit a 3L F8 engine. I honestly kinda wanna see someone tune that engine up for a semi-race endurance build in a super compact ultra light car and absolutely send it. Like Rob Dahm but with a scotch yoke.

[@rdallas81]

Only under very specific circumstances. The engine probably can not be directly connected to a typical transmission. The linkage looks weak and probably loses a lot of potential energy through that. I don't believe it will go anywhere. A range extension engine should be a diesel. Actually mazda did a rotor engine for a range extender and its hooked to a generator that charges its battery ONLY. Its not connected to the wheels at all. They did a pretty good job with it.

[@didjterminator808]

@@rdallas81 that do be true - but we can still dream

[@foolicooli]

@@rdallas81 rotary engines aren't used because their oil consumption fuel economy and poor emissions. Diesels are good work horses but generally heavy weight. The geometry of the 3.0l V8 on a light frame say 90s Miata would probably handle it fine. I don't see these engines going in anything trying to be a tow vehicle or similar work load. But a few years in the market they may redesign the pistols to be stouter etc. These have great race potential imo. Slap on some solenoids for the variable timing and other things becoming more common in the race scene like the newer F1s with the weight savings I could see these maybe being banned like the old road runners did from nascar being too aerodynamic

[@rdallas81]

@@didjterminator808 I do. So many ideas. I have ideas! Just crazy this world is dominated by substances, drugs, violence, media, etc etc. All revolves around government, money, lies. We need a new coalition. We need new people to provoke involvement like it used to be. Now, with media and "independence" people have grown apart. A great falling away it seems. Imagine a world where China, Russia, Japan, UK, can go work together and invent new technologies together. Imagine what problems we could all solve. Instead- people choose to make enemies out of their neighbors. And they expect their children to do "the right thing"? Sorry. Just venting. I like these engines and technologies because we can have 20 different people from 20 different countries and its like it doesn't even matter. We all speak the same language when it comes to technologies.

[@budthecyborg4575]

The flat non-boxer addresses basically all of the flaws mentioned in the first video. Bravo to the Sytech engineers. Let's hope Porsche and Subaru can adopt this configuration ASAP.

[@Wingnut353]

It absolutely does not address all the problems... that engine is obviously going to have high wear on that scotch yoke.... and probably need replacement every few tens of k of miles... while normal boxer engines last hundreds of thousands of miles with minimal maintenance.

[@Imagineering100]

@@Wingnut353 Yes it will it looks to me it has more surface area to wear out. I don't see the big car company use this they have too much invested in normal engine design and put this into production yes billion$ and 5 years and then if they have problems with it when they have sold 100000s of them well say goodbye. Not just that the car companies have known about this for decades if it was good, they would have done this decades ago.

[@CountChokcula]

@@Wingnut353 they can make it a roller bearing

[@michaelpielorz9283]

The internet is floodet with new engine designs that have one thing in common: even Wile E. Coyote wouldnt adopt them (:-)Dear boys, before praising them like a golden calf sit down and THINK for one miute (only if it is possible for you!!

[@michaelpielorz9283]

@@WaldemarPerezJr Please stop taking those colorful pills !!

[@fredericocorrea9814]

I love this guy's zeal and understanding of engines and engineering. He singlehandedly has caused me to look forward to new technology in the world of engines. The way he breaks down the science and evolution is incredible. Thank you so much for sharing your knowledge, I am in your debt. Another great video.

[@almostbutnotentirelyunreas166]

Been watching this channel for some time now, going from strength to strength, focusing on FACTS, rather than hype. There's an engineer in there somewhere, directing the excelelnce of the information and the video quality....Congratulations, keep this up! A credit to YT.

[@argledotorg]

The bearing surface is probably made of a relatively soft metal, since it appears to be made for "easy" replacement

[@wobblysauce]

Just a bearing material…

[@micgalovic]

Easy replacement is arguably more important than maximizing wear life. Doing an easy replacement job twice is better than doing a hard replacement job once.

[@IIGrayfoxII]

@@micgalovic Stripping down the engine is still costly for the customer

[@budthecyborg4575]

In high end pocket knives they like to use phosphor bronze washers to make a smooth pivot, not sure if those are up for the heat though.

[@flexairz]

I am sure the designers have thought of this too...

[@wingnut2893]

The overwhelming enthusiasm is contagious.

[@concoat]

I believe Commer commercial vehicles made a similar diesel truck engine back in the seventies, sounded amazing.

[@max_power8510]

Seeing your happiness and enthusiasm is what makes the heart of this channel beat. We feel just as enthusiastic as you about seeing new engine technology become available and the exciting possibilities of adding more power! Your smile at the end of the video really summed up why I started watching this channel.

[@alanbunder9068]

I love how excited you were scrolling through all the data on the website, great video!

[@originalni_popisovac]

no u dont

[@GL0BETREKKER]

the low center of gravity seems great for sports car applications, and so compact too. Cant wait to see more of this engine

[@JohnKickboxing]

This engine would get worn fast and badly, due to high friction. They need to add some rollers there to solve this problem.

[@zaccheus]

If the engine is designed from the start as a range extender, it would certainly be possible that it could have an oil priming system that developed oil pressure before a start. Engine start is where a lot of bearing wear comes from because there is only an oil film, at best, to lubricate the journal bearings.

[@Eikenhorst]

You could solve that by starting an oil pump for this oil a few seconds before starting the main engine. Startup goes from 1 second to a second or 5, but that is not critical if that is what is needed to use an engine with plenty of advantages. But I agree that a range extender application makes more sense

[@zaccheus]

@Eikenhorst A delayed start doesn't seem critical. But we live in a world where CVT transmissions still shift through fixed ratios because customers don't like it when the can't feel the car shift 🤷‍♂️

[@AlexTrull]

Your honesty and interest always shine through, thank you.

[@hasanimam3102]

Once again this guy is here with knowledge that even your bachelor's in Automotive Engineering course won't provide

[@BitchinSpectre]

Must have gone to csu.

[@blackfrost273industries4]

I hope you also add in that I am also very, very satisfied that they shared so much information. That is awesome that they publish all of that on their website ! That made my whole month

[@user-hb8sq6ce9u]

But can you trust that information - are the curves in the graphs really measured or are they only sketched.

[@brendonrenken6811]

Also YOU! YOU ARE THE BEST GUY ON THE INTERNET! I have learned more from your videos then any other source or any kinda experience! Keep doing your thing!

[@thomaswomack3888]

I really appreciate how well you have presented all of this information in a way that is understandable and digestible. And props to Sytech for making this engine design work. I'd love to try one of their 8 cylinder engines in my old subaru and see what kind of lovely monster it would be. :)

[@howardking3601]

Really interesting and fun! You are a great presenter. You break things down very well and keep them simple. Thanks!

[@nhand42]

This engine was developed by CMC Research Australia over two decades ago. There were plans to put it into a hybrid concept car back in the early 2000s but that never happened. I would wager good money in the past two decades they tried shopping it to the well known manufacturers - Ford, Toyota, VAG - who all looked at this and decided against it. Selling it into China means they've hit rock bottom.

[@andgate2000]

Just in time for the elec invasion.

[@68404]

Actually, the only game in town is China. It is now the biggest car market in the world. China has evolved. It seems your prejudices have not.

[@frutt5k]

@@68404 You just don't understand things, do you?

[@mikescherrer4923]

@@68404China has evolved? Ok, Chinese bot. Tell Xi the propaganda isn't working. China is a doomed cesspool full of rats clawing at each other to stay above the rising water of the CCP's war on it's own people.

[@pugnate666]

Thanks for the update! Great to see a more mature version with extensive documentation.

[@javabean215]

The single piston rod weakness issue, you spoke about in the first video. And my immediate thought was to add a piston to both sides. This is pretty cool, and I'm hoping to see it get some production time to see how it does in the real world.

[@Nafeels]

Between this, Mazda’s SkyActiv, Alfadan, and LiquidPiston, I’m psyched that ICE engineers won’t go down without a fight. I’m super hoping that the Flat-8 engine makes it into production, which would make them one of the first company in decades besides Porsche and Lycoming to pursue this ultra-rare layout. If they do, I’d buy a sports car just to fit one.

[@virtusetglorie]

And free valve

[@joshuasimmons2412]

Check out achetes opposed piston engine it's a awesome design.

[@tommynobaka]

Realistically ICE will not be phased out like everyone thinks. The market will shrink, but ICE will have its place. I think its great that as consumers, we will have the freedom to either buy electric or stay ICE. Gas and Diesel stations will not go anywhere

[@harrywalker968]

i have a 351 c ford v8.. its 50 yrs old, no issues.. why do we need this bs.. all engines will run on lpg & produce oxygen out the pipe..so why spend trillions on all this inovative bs, hybrids, solar, EV,s wind, . its all garbage..endless power comes from sodium reactors,, we only have nuke because of weapons.. fact..

[@NathanaelNaused]

All they need to do is use hydrogen

[@matthewbeasley7765]

In your free body diagram at 13:30 - your missing the reaction force. You've caught that the piston is driven to one side, but you're missing that there is an equal and opposite force that's trying to push the yoke to the right. It would cause the yoke to pivot, and that's not good. It would turn the yoke effectively into a rod because it would come to rest with the yoke placing the pin / block in line with the wrist pin. In old steam engines, they resolved this one of two ways: - In single cylinders per throw, they put guides on the sides of the yoke that resisted lateral movement of the yoke. - In tandem opposed cylinders, the piston rods had guides. (Remember, old steam engines were double acting). In the modern equivalent, the opposed pistons are going to provide the bearing surface to resist the lateral force.

[@haphazard1342]

Thank you for pointing this out. It was a glaring omission from the explanation in the previous video as to how this force could be controlled. In the single-acting design, he has completely ignored the guide surfaces required for the yoke. This represents a second planar bearing surface that is subject to the same engineering constraints as the primary inside the yoke. It is admittedly easier to lubricate as one side is stationary, but represents a second wear surface and source of friction. As you point out, the double acting opposed piston design solves this problem by using the opposite piston to control the lateral forces. This introduces a potential torsion at the point where the pistons attach to the yoke "rod", which coupled with ease of manufacture makes a wrist pin sensible. I would not want to be the machine shop tasked with manufacturing the rod-yoke assembly if it were integral to the piston, and I would not want to be the mechanic who has to replace the entire rod-yoke assembly in the case of damage to the piston alone. Overall, the double acting design seems efficient in terms of reducing wear surfaces and efficient packaging. Whether the lateral forces on the piston can be managed effectively in practice is another matter.

[@MrChancebozey]

There was a radial four piston two stroke motorcycle using a similar concept to a Scotch Yoke design almost 20 years ago called the JJ2S X4 500. Great vids and content.

[@chrisbaker2903]

I remember my dad telling me about scotch yoke engines at least 60 years ago and the biggest problem he told me about what the amount of instantaneous torque. He told me about a two cylinder version hooked to a car transmission and it would sheer the splines off the input shaft to the clutch. He also told me about a 4 cylinder version that they put a propeller on, 8 bolts around the hub and they ran it up to half power and when they put full power it sheered all 8 bolts. I hadn't heard anything else about them since then and this must have happened in the 1950s or late 40s. I look forward to learning more.

[@Chris-oj7ro]

This engine is completely new to me also and I thank you for going over it in detail! Maybe you could make a video on other promising engine designs that still have potential, whether or not we can expect some commercial release in the near future.

[@shimy333]

Please do a video on Radial motion from Australia... I have been obsessed with their three piston radial engine ever since I saw a few days ago on Jay Leno with the new Myers Manx buggy... It sounds more amazing than anything I've heard in many years

[@thatotherguy4245]

An amazingly insightful and well researched video as always. Thank you for making this.

[@shriramvenu]

really great explanation of an interesting engine design! I wish SYTEC all the best.

[@_miobrot_603]

That flat 8 engine looks legit! I sure hope the production run is successful for them so they can expand their market to USA and Canada etc. Truly exciting, and thanks for the update and continuation of the scotch yoke engines. I hope that the flat bearings are made to last, maybe a titanium alloy to withstand the heat and load?

[@jonskid8929]

You are an engineer. Loved the design and your concise description, knowing the plethora of information you sifted through.

[@TheDryOneGaming]

This is awesome. I just made a scotch yoke reciprocating saw for my senior project. Definitely didn't know that mechanism was being used for engines, super cool.

[@padders1068]

Great video and as ever very well explained! Keep up the good work! 🙂

[@jebise1126]

and i said 8 piston flat one would be perfect sense for it in that previous video

[@armandtdupreez1026]

Awesome video. This is the nerd-out content that I enjoy the most, I'm so excited that there are still new combustion engine innovations that are being developed and proof tested. Thank you for the information and explaining it so thoroughly and passionately 👍

[@c.a.r.s.carsandrelevantspecs]

Thanks for this fantastic video! This is the kind of engine technology that gets me excited for the future! Keep up the awesome work! 😃🚗🚙

[@wernertschan320]

So much learning. With every video you post. Thank you so much for enlightening me!

[@bondisteve3617]

Thanks King. Really enjoyed this. Well done!

[@cannaroe1213]

What a fantastic video, you were the perfect chap to document this engine, good job :) Your excitement reminds me of how excited I got when i first learned about sleeve valves, or the PatCam system, rabbit holes rabbit holes rabbit holes

[@gregstandish6439]

I am as excited as you are Mr. Driving 4 Answers. Very cool information.

[@paulcooper9011]

I'm glad you acknowledged the off-centred crank position in the scotch yoke engine. I had thought that after a while and it bothered me with no way to see how this could be eliminated. The flat arrangement in this engine might help it a little by putting that friction across two cylinders but probably not by much.

[@chir0pter]

D4A you really raise the bar with your videos. Thanks for all your hard work that I'm sure it takes to make such smooth and informative videos! 11:52 this is why ICEs will always be more interesting than EVs...designing, engineering & building parts that have to work in atom-space over millions of cycles is just inherently more aesthetic and fascinating

[@connorbingel7134]

Motors are cool but not that cool. They also aren’t at all intuitive. Engines are just way more interesting

[@redshift6170]

The engine was used as a range extender engine back in… 2000. I thought it looked familiar, it was a concept car called the “aXcessaustralia II”. Not sure it has come very far in the last nearly 25 years since then unfortunately.

[@DrTheRich]

Could also be other issues, battery technology might not have been good enough for it to make a sellable car

[@jimmydesouza4375]

@@DrTheRich Battery tech hasn't improved since the 90's.

[@DrTheRich]

@@jimmydesouza4375 ah yes, how could I have missed all hose lithium ion battery cars driving everywhere 30 years ago...

[@jimmydesouza4375]

@@DrTheRich No idea, but you did. The original ranger EV which started selling in 97 had Lead acid (obviously), NiMH and Li-Ion options (though I beleive due to a lack of sales the Li-Ion option never went in to production). GM EV-1 (96) also had the same, was originally released with lead acid but was sold to buyers with the idea that they'd be able to replace the lead acid with NiMH after gen 2 (1999) came in to production (which happened) and then to Li-Ion when gen 3 (planned 2002) came in to production (once again due to a lack of sales never happened). Again, the technology hasn't changed, all that has changed is the marketing. Even the purported range increases only come about due to massive increases to the physical size and weight of the battery packs in newer EVs, because once again it's the same tech.

[@DrTheRich]

@@jimmydesouza4375 i never said liithium ion battery didn't exist back then. The technology back then to produce them at a viable scale, reliability and prive wasn't good enough to make it a sellable car... You point out yourself that all these cars that were promised to drive on lithium ion cars didn't actually go into production. So somehow it's weird for me to miss cars that weren't actually driving around. Probably because the technology to make those batteries back the wasn't good enough. Battery technology doesn't just include only the technology of the battery itself. It also means the means to maken them. Example: we know how to make graphite Right now. What we don't know is how to make it on a scale that's useful for any practical application. Aka the technology isn't good enough yet.

[@Hodenmaffia]

Like always a really good and informative video. Keep it up mate! Greetings from germany.

[@PetarMakTeacher]

Some years ago I worked with CMC research where the SyTech engine was designed and built, in conjunction with Melbourne University. The engine was incredibly smooth running and it was very compact due to the short conrods. Side forces on the pistons is negligible due to the solid connection on the conrod. Our test vehicle was a Subaru as it used Subaru heads and bolted directly into it. We fitted a test engine into a passenger vehicle (Passat) as VW were interested in the concept. Unfortunately, like so many other research groups, the funding dried up and it was shelved. It's great to see it appear again, as I know there was an enormous amount of work done by very dedicated engineers to make it run so smoothly and reliably.

[@nickrider5220]

Great find and very well explained.....this will be interesting 👍

[@user-wf3fn6fy7i]

Thank you @d4a for another great and educting video! I don't know if you are a contributer to wikipedia, but as you note there is no article on this engine, and I think it would be awesome if you would improve that marvelous encyclopedia with such an article. With your knowledge and talent in explaining complex topics, you could probably contribute to a heap of other existing and not-yet-existing articles as well. The wiki will only be as good as its users make it, you know😉 Keep up the good work!

[@nickname3471]

Thankyou for this fantastic content, 1st time I've seen this channel. Very well explained video.. I've subed.. Thanks again.. Cheers from Australia.👍

[@incolink]

about 20+ years ago I had a job interview with CMC power systems and discussed the engine and its development don't think i got the job but the coolness of it has haunted me ever since I'm really glad to see it went a bit further I remember them saying they used Subaru heads for a few porotypes

[@chrismckay3868]

To overcome the rocking of the pistons during a power pulse it might be easier to create a double scotch design with guides to locate the rod and prevent it from rocking.

[@phantomforester9337]

Thank you for extensively researching and pulling out the key factors that make the concept work. You have saved a lot of time for a Web explorer.

[@VadoVoodoo]

Thank you for your educational and erudite introduction to this fascinating new engine.

[@rocknral]

Thankyou for correcting the friction issue that you missed. ( 12:23 ) I pointed out in your initial video this problem with a fixed piston/ rod arrangement.

[@felixbaum48]

Holy cow! Three Liter 8 Cylinder Engine at 130KG is amazing! Lighter than the lightest 8cyl mass produced, the Buick 215, by a huge margin!

[@BuzzLOLOL]

A properly designed aluminum V6 would have been even lighter... as typical of Buick, they did it wrong...

[@phugwad]

I am quite familiar with the Buick, Olds, Pontiac, Rover, 215, 3500-4600cc engine, having swapped one into a Datsun 510 back in the late 70s. That engine weighed less than 144kg, fully dressed, not more.

[@phugwad]

If the point of this engine was to make electricity for range extender use, why use a crankshaft at all. Linear engines, no crankshaft, just a piston connected to rods with magnets, driving a linear generator, get rid of a huge amount of complexity and weight.

[@BuzzLOLOL]

@@stevel6660 - The Buick V6 was a shiiite engine for it's first 25 years... ran like a V8 with 2 bad sparkplugs... shook back and forth 6 inches at idle... until 1988 when it got balance shafts to help smooth it out some... better idea would have been a crankshaft with 120 degree throws... then natural balance with no extra shafts or weak split rod journals needed... except it would have been so smooth would make it difficult to sell most people a V8 upgrade...

[@BuzzLOLOL]

@@stevel6660 - Millions of aluminum engines were made for WWII aircraft... there should have been someone around to consult with... Britain found them... and the Buick 215" aluminum V8 started in 1950 for use in concept cars... hence why they had rocker shafts instead of individual rocker arms on studs...

[@RobertDerusha]

I think your explanation of the wrist pin might be negated by the opposed piston resisting any tilting of the scotch yoke. My guess for including the wrist pin is just to aid in maintenance and parts commonality. Love the vids bud 👍

[@intrigue175175]

Well done! Thanks for sharing, this is exciting!

[@unvaxxeddoomerlife6788]

I remember reading about these flat four scotch yoke engines in an Australian Fast Fours magazine in the late 90s. The Aussies have been working on these for a while.

[@S.ASmith]

I think that bearing plate being made from Incoly or Inconel would work fine. Hard wearing, good temperature properties and they don't expand much when heated either.

[@frostyl4269]

your channel really is the best educational automotive channel out there imo. really clear explanations, detailed descriptions and diagrams to help understand stuff. been watching for a couple of years now and every video is just as engaging and fascinating as the first one i ever watched when i knew so little about cars. keep up the awesome content, it rly is top notch :D

[@Cap.jose.Espinoza]

Love your videos dude , really great edited and informative , it would be great if hou could talk about advantages and possible disadvantages of the Liquid piston engine and or the REX engine from INNE Engine sounds really intresting !!!

[@brianohehir9515]

Man are you ever into engines, love your presentation!

[@reisman44]

Please look into the Taurozzi engine.The Petronas University of Malasya conducted tests to confirm its efficiency.Would really love a video from you on that engine.Great job as always.

[@MadRat70]

Yes, these engines are much better than a scottish yoke. The concept hasn't even been given a real chance to strut its stuff. So simple yet ignored.

[@ryndrssn]

Malaysia*

[@DJAizakku]

The flat 8 is giving me massive 60s prototype racecar vibes. Im intrigued to see what it could do in a performance application.

[@Bobdibob]

My narrator - you're an absolute scholar, thanks for the vids!

[@tonyjennings8199]

Wow, what an awesome bit of tech!

[@bardocz]

I think one of the main reason, that the rod and piston is not a one piece unit is simply assembly. With the piston rings, it would be pretty hard (maybe kinda impossible) to assembly the piston into the cylinders.

[@user-lo4er8wy9l]

Great content and an interesting engine. If the primary use case of this scotch yoke engine is range extension, then it is likely not going to succeed due to the added cost and complexity of having two power trains in car as well as the continued expansion of charging locations. Range anxiety for most consumers is overstated. As a generator, it may have some value.

[@browie316]

Very cool, thanks for sharing! I think this engine has many possibilities away from from it's current intended use.

[@DoReid0]

What an exciting time we live in, high horsepower in such a compact form. I'm very excited!

[@coltonkarges2656]

Couple other very interesting engines to look at… delta hawk inverted v4 twin charged (turbo and supercharger) 2stroke compression ignition received FAA certification last week… and the Higgs diesel 2 stage 2stoke.. currently doing engine testing… keep the new ideas coming!!!!

[@jlo13800]

All these new 2 strokes are coming!

[@idrifted1]

You could probable model these 3 engines in the Engine Sound Simulator to find out how they'll sound.

[@haphazard1342]

Somebody page @AngeTheGreat!

[@endurofan9854]

d4a absolutely is full of fun and usefull stuff, no argument on that 👌 thanks for sharing, its a gem

[@PDLM1221]

Yes this is great news ! Thanks for finding this as it’s not very common information. Rey good information that needs to be put out there for people to know who are looking to use this in their inventions that might end this motor to help bring to the market.

[@user-ru3bv1bo8i]

Amazing video and very interesting as always! Id like to know why the teeth of the gear box gears are in angle. Just a video idea. Again great video!!!

[@d4a]

Mostly to reduce noise. This is why you get that sound when you drive in reverse. The reverse gear teeth are usually straight.

[@patturk7408]

Yup. Straight cut gears do get noisy. I have fond memories of a straight cut M22 from the old days.

[@DanielFrost79]

​@@d4a Hence the sound of many racing gearboxes. No idea about you, but i love that sound. 😍

[@DrTheRich]

@@d4a Also reduced wear, constant contact means less vibrations to cause wear on the teeth.

[@CyberChrist]

@@DrTheRich Don't they also offer better strength?

[@FallsGaming]

Wow cant wait to see what Car manufacturer would implement this into their lineup!

[@krisztiantkacs]

Only Mazda is stupid enough for something like this 😅

[@danhammond8406]

It's been over 20 years since it was made. I'm betting it has been turned down by all of the manufacturers

[@finophile]

stunning stuff, thanks for posting

[@ProjectCarJunkie]

Great stuff, thanks for sharing this info 🔥

[@connorruss5976]

Another reason for the the wrist pin you may have overlooked is for modularity reasons, allowing different pistons for different bore size or different piston crown design

[@pizzablender]

Also manufacturing is a lot easier with wrist pins.

[@asdf8asdf8asdf8asdf]

Great find. Shows you how much information could be hiding out there in the open despite having easy access to "everything" -- sometimes it takes awhile to find "everything" 😊 .... really appreciate the in-depth discussion But also curious how this relates to the more conventional "liquid piston" engine design.

[@alexjames1146]

Thank you so much for that. Absolutely fascinating.

[@ChimeraActual]

Love your enthusiasm and detail! I've learned so much. Bear with me, this is really about hybrid systems. A number of years ago I was messing around with the idea of a wheelchair, I was in one at the time, that could stand the user up and move around with performance comparable to a segway. It would have to be an EV, and I thought hybrid, with a tiny rotary engine, wankel, or other rotary type as the chair was all tubes. As I understand it, the major maintenance issue for a Wankel is apex seal wear, and emissions, with seal wear increasing the emission problem.. What don't I know? It struck me that if apex seals were cheap and easy to replace, say at every oil change, a Wankel with is low weight and compactness would be ideal for a hybrid. Mazda seems to be planning on doing this for a future sports car. Full disclosure: I have an ND Miata so I'm cheering them on. I think the Scotch Yoke engine will have similar wear issues, but with greater consequences if not prevented, imagine slop between the drive pin and the box it rides in. Maybe three roller bearings sprung, or otherwise progressively held apart, to take up wear? What would your choice be today for an engine in a hybrid system?

[@klausbrinck2137]

If the SyTech-engine is used as a range-extender of an E-car, then its eventual vibrations are of almost no-importance at all, since they happen for a fraction of the driving-time, or even when the car is mainly parked...

[@flexairz]

With this you can use less toxic and easy exploding batteries.

[@lairdinho]

Not true, I wouldn't say. If you've driven a range extender car, the engine buzzing away can be quite intrusive, especially at town speeds. And as far as I am aware, the engine doesn't operate unless you're onboard / driving. Lots of reasons why you probably wouldn't allow the engine to run when the car isn't being fully supervised. Long story short, you'll be on board when the range extender is running.

[@klausbrinck2137]

@@lairdinho In Germany there´s a law, that you really cannot use the range-extender when parked, Cause the plague of all the exhaust gathering at one single place, wouldn´t be acceptable for all the people around it, walking the street... But the concern you expressed can be dealt with, an if the extender should burn hydrogen, exhausting anly water-vapor (I know, very unlikely, and I hate the odds of that trully happening, I hate the hydrogen hype), this concentrated-exhausts-concern of the german law wouldn´t be valid anymore...

[@jimmyc7269]

And if it runs at a fixed rpm and generate vibrations of the same frequency, then it would probably be much easier to deal with the vibrations.

[@klausbrinck2137]

@@jimmyc7269 ...the chance, that it then matches with the resonating frequency of ANYTHING else in the car, is virtually zero, u r right there !!!

[@bigblue729]

I don’t think they necessarily need the wrist pin in this case. Since the engine now has two opposing cylinders, the rod flex or twist is now supported by two cylinders. That being said I’m glad you mentioned it because it was my first thought in your first video and absolutely would be a bigger factor on an in-line engine. The wrist pin could still be useful in assembly/disassembly as well as servicing the engine. A piston/rod assembly would be an expensive part to have to replace due to the complexity of it. The ability to use different materials from the piston to rod may also be a reason to split the two. You could also use commercially available pistons, reducing machining and repair costs. I’m curious to see the long term reliability of the sliding bearing since that seems to be the biggest question for whether or not this is really commercially viable. 500hrs of run time really isn’t that much and if it needs rebuilt soon after that time frame then maintenance costs will likely kill the engine design for most applications.

[@MrJamesBanana]

Yeah, 500hrs is nothing for an engine. Especially if that is in multiple different test cycles. Also, the two cylinder version will probably vibrate a lot since there is no way to get even firing intervalls for it. At least without making a two stroke engine of it. Also highly doubt an engine like this will be able to handle euro 7, those rules seems kind of strict.

[@blinkybagger8342]

Though the double ended scotch yoke rod has another piston attached (presumably )at an opposite point of the combustion cycle, the forces may be less even momentarily as the combustion forces do their thing. Wrist pins may reduce friction and improve assembly & servicing.

[@kevinmurimi2176]

Trying to imagine the sound of a flat 8 cylinder engine makes me smile. Great video

[@Georgiaguntraining]

Excellent analysis. Thank you.

[@torque350hp]

I can't help think having a wrist pin at this stage is just the easiest step in development to connect them.

[@user-hb8sq6ce9u]

yes, are the piston and crankshaft different material - at least they might be easier manufacture as separate parts and then should be connected in some way.

[@boywhohasl1vedhascometodie469]

Really good video! I’m intrigued to see where it goes! I’d imagine it would have some good practical efficiency, but if it was put in a diesel format, the crank journals are not seeing past 10,000 miles. But overall, it would be an interesting journey for this tech!

[@user-dv1zg1yk7t]

Diesel predates benzine and is more prone to calking things up with carbon... Also high combustion temperature 🌡️ that makes it efficient is hot enough to release reactive nitrogen populations NOX bad for 🧬 biological chemistry - induces errors, unlike X-Men we get cancer if the cells don't die or get killed. Currently cancer can only be located with fancy radioactive ☢️ Sugers as it feeds, in growth phase. Can't target 🎯 what you can't detect "do no harm" 🙄😒 an all... So, the consumer needs to be isolated from NOX and other carcinogens. Target the conception phase of cancers. Diesel still has it's niche place in the world but it's top dog days been gone with the jet engine and now SpaceX's staple diet of meth... ane. They are quite progressive in displacement of cheracen too. In the future the jets should make the switch too but that would take more than a disruptive startup in large industries. Anyway not to go too far off on a tangent Diesel will be used on cargo ships until LNG can be easily managed or all the new nuclear powers decide to use the stuff for economic growth instead of deterrent and defense. But that stuff is rarer than gold so... Yeah probably not very many nuck ship 🚢 outside the Arctic 🐻‍❄️... Rail is more efficient and safer but people need jobs or they start things they can't finish... Again another tangent topic. In my defense Mr Diesel had a very troubled life success and suicide or robbery on a boat 🚢 - just can't be successful share things with shady people. 🤐

[@paulfuller5646]

Great explanation and detail, well done. thank you. The boxer engine name was coined for the pistons moving in the same manner as a boxer does when punching. The scotch yoke design, while innovative, operates in same manner improving upon the original boxer design, hence, “scotch yoke boxer”.

[@Tom89194]

If you look at the moving parts in a swashplate hydraulic pump/motor you will notice that the thrust from the pistons is transferred through a sliding shoe. This is solved by allowing some oil to travel down the piston into the sliding shoe. The oil film lifts the shoe off of the plate it is sliding on and the shoe and plate wear becomes negligible. The sliding block in this engine just needs to have enough oil lift to keep the metal parts from touching each other.