Volkswagen Created A Unique Engine - The Budack Cycle!

[@MotoDash1100]

"You know the cycle" _proceeds to mislabel the 4 Cycles_ Excuse me sir, it's: "Suck, Squeeze, Bang, Blow!"?!

[@versastyle5007]

It's like you're directing a dirty movie 😮

[@jasonstclair6293]

Came here to say the same thing

[@rumoara]

Same thing I thought😂

[@p60b4_xxgamerboixx]

this is Donut Medias terms for a 4-stroke to people who don't know.

[@DeathMonkeyX]

@p60b4_xxgamerboixx its not theirs, they have just used it, and made a meme song out of it

[@Presy_P]

Caterpillar engineer here: Nice video, but that's not a new cycle. It's just a miller cycle, and caterpillar has been using it on their natural gas powered industrial engines for years

[@TheJamesLykins]

Ever think they are two different things?

[@mr88cet]

@@Presy_P, hmmm… My off the cuff recollection is that the Miller cycle is Atkinson cycle plus a turbo.

[@Bootchair]

Leave to the Germans to complicate things and rename it.

[@peglor]

The Atkinson/Miller cycles leave the intake valve open for part of the compression stroke rather than closing it before the end of the intake stroke, so the rising piston pushes some of the air/fuel mix back out the intake as it rises before the intake valve closes rather than closing the intake valve before the piston has completed the intake stroke. Atkinson/Miller cycles never have a pressure less than the ambient atmospheric pressure in the cylinder (Ignoring scavenging/resonance effects in the intake/exhaust manifold and the throttle restriction), while the Budack cycle does. The question is, does drawing a vacuum make it work any better. The upsides are the intake air doesn't have to change direction and go back out the intake valve as the piston goes up at the start of the compression stroke, but the priority for this engine cycle is thermodynamic efficiency rather than volumetric efficiency, so that's not really an issue, though presumably there's more loss pumping air/fuel that's not being used back out than not pumping it in to begin with. The downside is the possibility this vacuum will cause other effects like drawing oil past the control rings into the combustion chamber or pulling the inlet valves open against the springs (I doubt if this can happen given how stiff the valve springs need to be to work reliably at 5000 rpm). Another interesting possibility is that for the same compression ratio the air/fuel charge will probably be slightly cooler in the Budack cycle because the same small volume of gas stays in the cylinder longer, so the engine's cooling system has more time to take heat out of it as it compresses. Unlikely to make a huge difference on emissions or anything, but the IC engine industry has been creeping up on the Carnot efficiency limit (With emissions restrictions) for a while, so splitting hairs like this could make or break the viability of the engine. A very interesting possibility is that with variable valve timing type control of the exhaust valves, the vacuum part of the intake stroke could be used to draw exhaust gas back into the combustion chamber eliminating the EGR valve as a separate part of the engine. If the engine has variable valve timing on the exhaust valves already it would be a simpler solution.

[@liamwoodman4950]

It's not quite a Miller cycle. Here the valve closes early. In a Miller cycle they shut late, requiring a supercharger or similar.

[@mr88cet]

Interesting indeed: As opposed to leaving the intake valves *_open longer_* for the Atkinson cycle!

[@JETZcorp]

I think Atkinson makes more sense! This cycle creates pumping losses trying to pull against a closed intake valve.

[@gabrielfernandessilva3707]

It is the opposite. Having the valve open longer will make the engine lose energy on the turbulence at the valve. While it pulls on the closed valve while it goes down, the atmospheric pressure will push the piston back up on for some fraction of the compression stroke.

[@neolerades2987]

@@JETZcorp In my opinion - the vacuum acts like a spring - the piston will be pulled by the vacuum as it moves up and the energy will return.

[@Giuliana-w1f]

​@@JETZcorpthat same vaccum can pull the piston back up. Atkinson creates losses by pulling the air in, then having to pull it back out

[@Defianthuman]

Its the same thing with the atkinson cycle not closing the valve until 20 to 30% of the way back up during the compression stroke both are limiting the amount of air.

[@lukeberry94]

I did this with an old Subaru, all I had to do was put the timing belt on with the cam sprockets in the wrong spot.

[@sarcasticguy4311]

You were an INNOVATOR!

[@HexFire03lmao]

​@@_TheDoctorNo I'm not sure that's what he said at all

[@nine1690]

Those “little consequences” include lower torque at absolute best, which means you’ll have a harder time with uphills or loads, and at absolute worst results in you completely ruining your engine. And that’s assuming it can be modified in that way. If you’re not intensely familiar with the engine and how to modify it into an Atkinson or Miller cycle, I wouldn’t suggest it.

[@PC_CERTIFIED]

@@_TheDoctor 🤣

[@daneda8997]

it's not bad mecanic, that's science

[@williamcapps6120]

I was gunna say, like the Atkinson cycle, but it closes early instead of late. I feel like that's functionally the same but with the added benefit of extra oil consumption lol.

[@bobbygetsbanned6049]

Ha didn't think of that, so when it closes the valve and basically starts pulling a vacuum on the cylinder, it's probably sucking oil through the rings?

[@callummoss5940]

Not to mention more pumping losses

[@dovydaskaminskas4227]

@@callummoss5940 less pumping losses

[@jersey3686]

Less fuel burned also allows lower octane fuel

[@LovejitKharod]

@@bobbygetsbanned6049 Cylinders would already pull a similar vacuum in a low throttle environment anyway, I don’t expect there would be significantly more vacuum (vs standard, not Atkinson) without being very low on power. I imagine it would just be a different way to manage/restrict airflow with less pumping losses like valvetronic.

[@golfbravowhiskey8669]

The old Pratt and Whitney radial engines from years ago used the same system. They're not breaking new ground, and it was abandoned just due to duty cycle procession. PW abandoned that type of engineering just due to excessive premature wear for the prolonged exhaust gases being on the sleeves. Yamaha did the same thing back in the 80s.

[@jamesbowen2105]

@@golfbravowhiskey8669 covertimg it into variable wavetable algorithms is "new".

[@TucsonDude]

Are you an engine designer? I'm a M/E and this blew my mind.

[@adotintheshark4848]

P/W did it to lower the compression ratio and cool the chamber, as their pistons were so big they were worried about detonation. Those engines only ran about 6-1 compression, yet they still had to run very high octane Avgas, around 145.

[@moshet842]

​@@TucsonDude My question is, what about the extra energy required to essentially pull a vacuum when the intake valves close early? I assume that is taking away some usable horsepower and efficiency.

[@deathsheir2035]

@@moshet842 That's why the cycle is trading power for effeciency. Less power, more fuel efficiency, for an increase in maintenance cost, because of the extra wear and tear the cycle puts on the engine. There's a reason P&W and Toyota abandoned using the Atkinson Cycle. Budack Cycle, doing the exact same thing as Atkinson Cycle, will also have increased wear and tear on the engine, increasing maintenance cost.

[@Dave5843-d9m]

It’s also a great way to avoid direct injection clogging the inlets with unburnt carbon.

[@KR-jg7gc]

now talk about the disadvantages like the other people did 😂

[@incrediblehonky1]

It’s a bold strategy Cotton, let’s see if it pays off!

[@MichChief]

Can an average joe understand this?

[@matthewcohen9582]

Trying to understand how the stroke changes with a difference in compression. Also, by closing the intake valves early, in an airtight cylinder you're going to pull a greater vacuum on the combustion chamber if the piston hasn't completed its stroke. The time differential may be minimal, but for that brief moment in time, wouldn't that act like a brake on the piston? If it does, by slowing the rotational speed of the crank across all the cylinders, won't it then require more work (subsequently less power output) to turn the crank? Unless, of course, this is a variable action which only occurs some of the time through cam phasing and only occurs during low-load situations?

[@treymiller5736]

That vacuum would also still be active when it starts the compression cycle being power back into the engine as well. (Though because of friction half of it will be lost) After the exhaust stage because of the very hot gas you still have a lot of potential energy rapidly forced out of the engine rather then being captured. This would decrease that. (We also choke air into the engine so the engine fighting a vacuum is normal outside of the throttle be wide open, if gas mixture is lean it burns slowly or fails to burn at all)

[@Clyde-2055]

@matthewcohen - Yes, and yes …

[@matthewcohen9582]

@@treymiller5736 Yes, but think of it this way: If you have a certain volume of intake charge (fuel/air mixture) into a cylinder which operates from TDC to BDC like any other reciprocating engine, that cylinder is going to have a fixed volume of displacement. For the charge to enter the cylinder, the chamber has to be under a vacuum, which begins after the piston is traveling down from TDC and the intake valve(s) begins to open. The delay from TDC to where the piston is at when the valve is coming off the seat is what builds the initial vacuum to pull the charge in. As the valve opens, it pulls a certain amount of fuel/air in, and this ceases when the valve is closed. Then as the piston comes up, the state in the cylinder switches from vacuum to pressure as it compresses the mixture to create potential energy. My point is that the cross from vacuum to pressure inside the cylinder is a specific threshold determined by the volume of the cylinder and a "normal" amount of intake charge. If you bring a lesser amount of intake charge in by closing the valve before the piston has reached BDC, not only have you reduced the volume of intake charge, but you are also pulling further in.Hg. worth of vacuum in the cylinder, increasing the linear distance the state has to travel before crossing the pressure threshold. Further vacuum than normal means further load on the piston before it reaches BDC, and for that brief moment in time, that piston saps kinetic energy from the crank, essentially creating rotational drag, which is compounded when it's happening across all of the cylinders. What EE said about lowering the compression ratio is correct, because the volume of charge relative to the volume of the cylinder is lower. But the stroke is fixed by the piston, rod, & crank. Reducing the compression ratio via fueling doesn't make the piston travel further, or less. It just lowers the potential energy of the cylinder, in the name of using smaller quantities of fuel per cycle.

[@treymiller5736]

@ yes it would reduce air intake that’s the design. I think the idea is the vacuum of the design is “less” harmful then the gains they get from capturing more of the potential energy of the stroke. (In terms of efficiencies in terms of max power you absolutely lose) (or at least that’s the theory and since they built it I would assume it has some merit)

[@jstefa2]

@@eerso9301 google overcompressed engine, its a neat invention from aviation in ww1.close the valves early and you get the compression losses of a 9:1 and power efficiency of 15:1

[@s4dg]

combine this with a toggle-able VVT system, and you could have an extremely efficient car which can take regular gas, and an extremely powerful car on high octane fuel.

[@nirodper]

it's called valvetronic

[@Darkcruzer23]

and still be unreliable and not easy to work on

[@dirkfrazier9779]

So instead of a 400 HP V-8, I'm now riding a 125cc moped because it gets great gas mileage?

[@TonyBogdanov]

My thoughts exactly, if you're going to cap an engine like that, why use it in the first place? Just use a smaller one, you'd gain even more mileage from it being lighter and less complex (less cyllinders for example). I never understood eco-tuning, you pay for the whole thing then proceed to use 60-80% of it...

[@justw4lkbesideme]

​​​@@TonyBogdanovlower price, not good... (My assumption)

[@SEKTORMYNE]

Engine dropping that NY Compression on some fire beats🤘🤘🤘

[@mob1235]

If Volkswagen creates something, be aware it will not hold longer than 60k kilometers.

[@NathanFromme]

The cylinder heads on this engine are 30-40k miles replacement maintenance. It’s like $8000 to pay a shop to do it. I’m a VW tech for 4 years now. All the gen 3 EA888 engines in the Tiguan suffer from this. Some Audi q5s as well

[@INTEL-REDACTED]

VR6 disagrees.

[@hardcopydk3001]

well my engine has gone 190.000 km so far with ease

[@thecoolguy9364]

​@@INTEL-REDACTED vr6 and 1.9tdi are both the kost glorious engines gifted to us

[@thecoolguy9364]

Most*

[@garybarbourii8274]

Wow I've been designing just an engine and had planned to convert an old diesel to this style engine and it's already being done!

[@UrbanistAstra]

This would be great when combined with either freevalve (if it was available on a regular car) or VTEC

[@Akira-nw4jl]

Totally agree with you because although this modified Atkinson cycle saves gas, it makes the engine weaker but when timed correctly you use the weaker cycle when you don't need power but can instantly raise compression when more power is demanded. Great?

[@SargentoDuke]

this is actually e-vtec

[@nosky3132]

love the moment the engine started the combustion cycle over and over again

[@euroovca25]

yes and it consumes 5x more oil than it did before. so efficiency out of the window.

[@erikhordnes7408]

I dont see how that would increase oil consumption

[@maszkalman3676]

@@erikhordnes7408 Because since this shłt got in car volkswagens eat up 1-1,5 liter oil per 1000 km if they got odler than 5 years old....

[@monty9373]

@@erikhordnes7408 Overexpansion during intake rendering cylinder pressure a vacuum relative to the crankcase around BDC. I had the same thought, but there's plenty of other details left out. Also, the better compare/contrast is likely is Miller cycle, not Atkinson.

[@erikhordnes7408]

@@monty9373 Oh yeah that does make sense. Although i think 5x is an extreme overestimate.

[@wtfiswiththosehandles]

@@erikhordnes7408 It's a VW. I had a new passat that consumed over 1l of oil per 1000km. VW said it was well within spec.

[@kyototomokui6676]

“You know the cycle!” Yeah, it’s “suck squeeze bang blow,” not the full legal name you just doxxed 😂

[@LordmonkeyTRM]

Government name

[@stickmouse5002]

who gave you that name? a toddler?

[@kyototomokui6676]

@@stickmouse5002 Who, me? Or the cycle?

[@stickmouse5002]

@@kyototomokui6676 the cycle, ovbiously

[@overzealousmaverik]

That sounds just like they changed the duration of the intake lobe on the cam and patted themselves on the back and to make themselves feel extra special called it something new. Gold stars all around.

[@lucianopaoli1259]

Yeah i mean, isn't it just the same thing as having a bigger engine and using less throttle?

[@teebob21]

Different timing regimes are what make Atkinson cycle engines different from Otto cycle engines, and different from Budack cycle engines. Yes, the differences are subtle, but if you don't have a deep enough understanding to grasp the distinctions, try to do better than to just mock the idea.

[@AnotherWisenedOne]

Don't forget the participation trophies there!

[@florianvelling6427]

All of these processes have distinct pressure -volume and temperature - entropy diagramms. The shape of these diagramms is what defines a thermodynamic cycle process (all internal combustion engines with a piston use a thermodynamic cycle process). So it is by definition something else, so you also gotta call it something else.

[@covoxer]

It is not new. Toyota is selling this in huge numbers for over a quarter of century already. With each Prius and some other models. ;)

[@charliehorse8686]

Question: Do engines exist where valves are moved buy solenoids or other electric actuators, rather than with a mechanical cam?

[@jamesgizasson]

God, I hope not! XD

[@gonzaloestigarribia3256]

@@jamesgizassoncheck koenigsegg free valve engine

[@FGuilt]

I feel like that would run the risk of misfires. Timing chains make it practically impossible for the engine to not sync with the cams. Less electronics the better.

[@charliehorse8686]

@@FGuilt I agree it would be problematic and likely lead to catastrophic failures. BUT...Some creative things could be done with adjustable valve timing on-the-fly. Perhaps in a race car where the engine is expected to push risky limits anyway.

[@jamesgizasson]

@@gonzaloestigarribia3256 Safe to say I'll never be digging into anything Koenigsegg makes. :3

[@robinfutt8336]

What is the benefit of this technology compared to an intake throttle valve?

[@nightsidechild.]

Simplicity, it's just different timing. also, due to the decrease in pressure in the suction stroke, the air temperature decreases, which reduces knock

[@Giuliana-w1f]

Longer combustion compared to compression, less energy wasted to the exhaust

[@mnxs]

​@@nightsidechild.The reduction in temperature from lowering pressure is immediately lost when the compression stroke starts and returns it to the same pressure again. However, because the charge effectively spends longer in the cylinder, it's possible it can bleed off heat better to the walls, and thus lowering overall temperature that way.

[@jevoniscool]

​@@mnxs wouldnt the walls be hotter than the air was when it entered the chamber, thus transferimg heat on the intake stroke?

[@JohnBorden-fu6my]

​@@jevoniscooldrop in the compression ratio automatically decrease cylinder wall temperatures

[@KevinMc-b6f]

all of this went right over my head , but nice shirt! : )

[@Wised1000]

Very similar to the Atkinson cycle...AKA virtually the same.

[@EngineeringExplained]

Difference is valve timing, close valves early vs close valves late.

[@bavarianbarbarian2443]

I would say this is called the Miller cycle. And is nothing new...

[@Jamil-j5s]

This is a messed up Atkinson, less air=bad performance, unburnt fuel, poor efficiency and emissions. Proper Atkinson does not lower the compression ratio but the expansion stroke is lengthened

[@bavarianbarbarian2443]

@Jamil-j5s There is nothing messed up about it. Your conclusions are just wrong. Why would there be less air than in an atkinsons cycle? If you design an engine with higher CR an then lower it on purpose with atkinson/miller, then you purposely designed an engine with higher ER. AKA "expansion stroke is lengthened"

[@imtheonevanhalen1557]

Ya know I used to think when home porting heads just a straight through to the piston was the goal, and then I watched a vid of John Kasse cutting a hole in the intake runner of a HP engine on the dyno. He said the vacuum pules were extremely violent, to the point he was worried they would break his finger....and then it dawned on me...the intake valve closes, and creates a massive pressure wave behind it, ready for the next open cycle of the stroke....balancing the timing of those two events creates the magic

[@-gp-78]

Ok, I have this serious question. Why adjust the cam to close earlier when u can just control the amount of fuel to make the cycle efficient?

[@SatlaE]

because when you burn lean fuel it burns very hot and can be too much for the engine to handle, like melting things. you cant be lean with high load. but this is efficient in terms of energy, look up attkinson cycle.

[@-gp-78]

@@SatlaE does it produce more power ? Anyways thanks man

[@SatlaE]

@@-gp-78 what produces more power? the lean burn or attkinson?

[@-gp-78]

@@SatlaE comparatively what produces more power?

[@SatlaE]

@@-gp-78 well technically attkinson cycle does not produce more power but more efficiency. but lean burning basically will produce more power because you burn all the fuel completely, but you face limitations like temperature

[@Giuliana-w1f]

Would be interesting to see this combined with multiple cam profiles (one Otto, one Budack) and forced induction (being basically to Budack what Miller is to Atkinson). Would be great with a lot of boost, relatively low compression on Budack mode (when in high boost), and a normal-ish compression in Otto mode (for when in lower boost). Also, why are so many people confusing this with the Miller cycle? This closes the valve earlier rather than later (compared to Otto), and has nothing to do with forced induction.

[@what9418]

Doesnt a throttle body limit the intake air as well and basically does the same thing? Please explain the difference.

[@LovejitKharod]

Great question, the throttle body limiting the air creates pumping losses, which is the energy expended to keep a continuous flow of air through the restricted opening. As if the engine is constantly sucking through a straw. This alternative of valve based air restriction could even be an alternative to a throttle body, which is basically how BMW valvetronic works. If I understand correctly, since the air is already moved into the cylinder before being dropped to a lower pressure, we only deal with a smaller amount of effort to pull the slight vacuum within the cylinder, which will then return the energy during the compression stroke. So it would be a similar solution with less wasted energy along the way.

[@bechirbenothman5453]

that will reduce the torque produced by the engine as well as the HP. It should be usefull only in eco modes.

[@malcolmmackenzie9202]

Would be cool to have that changable so you can still make max power with full cylinder pf air and fuel

[@Coolgamer400]

Better specific fuel efficiency effectively gives you more power per fuel. The principle doesnt necessarily mean it has less power. Additionally the mechanical compression ratio can be too high for "normal" cycles (knock).

[@b0bsaget007]

​@@Coolgamer400 it does make less power when running like that because it is not able to take in as much air due to the intake valve closing sooner. What the OC is saying is to switch between this Budack cycle and the normal Otto cycle with the normal intake valve duration for more power when demanded. And, if I'm not mistaken, the VW engines that use this Budack cycle already have this switching ability in place.

[@MaxMustermann-bm7qt]

Of course it can. You just don’t close the valves as early.

[@Giuliana-w1f]

@@b0bsaget007 if the engine is optimized for Budack, the compression ratio would be relative to that. With a 2.0L BDC to TDC, If it was closing 20% before BDC (1.6L intake close to TDC), creating a compression ratio between intake close early and TDC of 10:1 (0.16L at TDC, 1.76L at intake close); if you changed the cam to one that closed the intake at BDC, you'd have a 2.0L with 13.5:1 compression ratio (2.16L BDC, 0.16L TDC). If the initial compression is higher (likely is), the displacement (BDC to TDC) is bigger, and/or the difference between intake close and BDC is larger, the final compression would be even higher (to likely unusable levels, even NA). People have done different cams in Atkinson engines for high compression (Atkinson closes the intake after BDC instead of before it, but the effect is basically the same), like G&G with a 2AR-FXE in an MR2

[@TeemoDIY]

Point seems to be using intake valve to regulate power instead of separate throttle valve (as usual). The benefit may come from related thermodynamic effects, that is there is no intake manifold vacuum. Elliminating intake manifold vacuum increases efficiency because now thermodynamic cooling effect occurs directly inside the cylinder. This increases the temperature difference to work with. Kind of in-cylinder pre-cooling. All this applies to the low engine load conditions only. At maximum load it most likely works exactly the same as conventional engines.

[@johnbelwell2461]

Everything's gangsta on this engine up to the time the piston rings start to wear 😂😂😂

[@gertvanderhorst2890]

I'm afraid you made an educated prophecy.

[@johnbelwell2461]

​​@@gertvanderhorst2890It is common sense if you know the working principle of an ICE to know what will go wrong, this engine creates some vacuum by closing the intake valves early for this "variable" compression, thus when the piston rings stop breaking in and start to wear which happens after around 50k miles with ideal oil change intervals (around 150 hours of engine operation for constant load per aviation standards for ICE), what happens is the engine eventually starts drawing air from the bottom end. 1) There is extra wear on the piston rings and bearings by the two way loading and movement of the piston unlike a normal 4 stroke where it is always in compressing state in all the strokes (itake is also "compressed" by either atmospheric pressure or forced induction, and exhaust is forcing the gases out). 2) When this happens and the engine is working under this operation mode, the vacuum created will draw oil into the cylinder, this will then cause two problems: A) Excessive oil consumption B) Extra wear as the cylinders can starve of oil C) Excessive gunking of the piston rings leading them to get stuck. 3) All the above can get a dramatical increase with the engine loaded at low RPM due to the extra time the piston has to complete the stroke. This can only work flawlessly in stationary engines which are usually well maintained and overhauled per schedule. While it is very common to take a cylinder head off or even replace a cylinder and piston in marine and stationary engines as regular maintenance, or even get your team to overhaul the whole engine, in cars it's a whole different story. You get the guy with the 90's Corolla saying it "burns oil" but works without needing any other maintenance, and we're talking about an engine that not only it does not operate as designed at any range, but it has stopped being within factory specs 30 years ago. ICEs are and need to be as precise as Clockworks.

[@johnnycarson67]

Okay it's more efficient. So just how much better mileage I would have engine yet with the budack cycle? Also can the same thing be applied to diesel?

[@ChrisBigBad]

The chairs on the Titanic's deck are exceptionally well set up today ^^

[@camsmith4047]

With a new water resistant varnish, cost us millions to develop

[@Bijorak]

so will they burn more oil?

[@cartert147]

Genius!! sick shirt too

[@No5elfCTRL]

This concept is very old. If it was Genius, all cars would use it

[@KaosProject21]

Also, you're killing it with the jokes lol I love Engineer/Great lakes dry humor lol

[@kemottomtr]

What's the difference between those smart engine cycles and not opening throttle body all the way up? In both cases we get expantion radio greater that compression ratio. Why to make simple internal combustion engine more complex? Is it worth it?

[@jakke1975]

duh if you can increase efficiency somehow, it is always worth the extra complexity. Maybe you don't see the big difference from 1 model to another but if you look at all the small increments made over the years, total efficiency numbers have LARGELY increased. Higher efficiency means you consume less fuel and have less waste to pump in the air. With all the climate crisis issues, I'd say it is quite important and quite relevant.

[@joshuagordon4267]

Great way to not answer his question

[@ZealothPL]

Simple internal combustion engines are too inefficient and polluting

[@kemottomtr]

You dont get my question. Asked about difference between closing intake valves earlier during intake stroke and simply leaving throttle body not fully opened. In both cases we get smaller amount air-fuel mixture inside combustion chamber and smaller pressure during compression cycle. Where that efficiency comes from? Both power and exhaust strokes in both cases look the same. Wheres the difference?

[@kemottomtr]

@@jakke1975 I get it, more efficiency, even slightly is a step forward. I'm just wondering where that efficiency comes from. Trying to understand the physics behind it. Is it something with evaporation of fuel, or swirl effect, maybe enables leaner mixture to ignite? If you know, please, explain.

[@luca6819]

I think Fiat's multiair also already did that, when appropriate conditions are met

[@NidalDajani]

It is another way of imitating Atkinson cycle. Either you close the intake "early" (to reduce the compressed air charge), or you close it "late" ( allowing some of the inlet air to return back into the intake manifold, thus reducing the compressed air charge). Closing "early" results in less chamber pressure to fight against during compression stroke. Closing "late" results in less air mass to compress during compression stroke. While lclosing early (during inlet down stroke) robs the piston some of its down inertia which tends to slow down the piston (parasitic power loss), closing late pumps back into inlet manifold (along with part of the fresh charge) some exhaust gases which results in "diluting" the next "fresh" charge, which translates to less power.

[@bonez72392]

You can also open the intake valve late and cause a pressurization effect in the intake.

[@AR_434]

Isn‘t that just a Miller cycle?

[@keenheat3335]

I'm guessing they named it that way to avoid licensing issue.

[@matteocristini6221]

If I recall correctly it's actually the opposite. Doesn't the miller cycle keep the intake valves open during part of the compression stroke?

[@siontheodorus1501]

@@matteocristini6221 that is atkinson cycle

[@matteocristini6221]

@@siontheodorus1501 I just checked and apparently atkinson and miller do the same thing, but they're different mechanically

[@AR_434]

@@matteocristini6221 Yes, Miller opens before BTC and Atkinson after BTC.

[@zaz4667]

My car uses the Fred Flintstone stroke and when my feet don't get traction my shoes wear out fast!

[@fixingstuff8117]

I have done something simular with my turbo diesel. Made the valve gaps of exhaust valves bigger, so it opens at about 10 deg Bbdc and thus closes earlier. Also mzde intake valve gaps from 0.4mm to 1.5mm. Thus intake valves opens late and closes early. I get some EGR. 15km/l in town. 17.6km/l on highway. I am still busy testing things. In town the exhaust burns clean with no soot build up, so clean to touch. Not yet on highway, still figuring it out. Basically it is Miller cycle with expansion ratio more than compression ratio. So you can run with less fuel to get same fuel ratio. Less cam energy needed to open valves. More time for fuel to fully burn out and more energy extracted before exhaust valves open, with cooler exhaust. And no the velve lifters does not hit the valves harder, the slope is basically the same according to the engine engineer drawings.

[@vanjamenadzer]

How does it affect the power output and what car do you drive?

[@fixingstuff8117]

​@vanjamenadzer I never use all the power of the engine, so I can't honestly tell. But it has plenty enough power. I detuned the 'smoke screw' on the injector pump long ago for less fuel anyway. It is an Isuzu 2.8l Turbo diesel.

[@Workerbee-zy5nx]

Brilliant..oh and love the shirt.😂

[@ahmeeeeeeeeeeeed]

I love that shirt

[@ThisIsBrendon]

Budokai is definitely my favorite cycle

[@sinthetikk6516]

Its just the miller cycle. Close the inlet earlier before BDC and the piston creates an expansion effect which cools the cylinder. The atkinson cycle keep the inlet open for longer, after BDC its still open creating a “leaking” effect where the compression stroke pushes some of the air mixture back into the inlet before it closes

[@brianschuetz2614]

Love the shirt. Not sure why anyone would find it strange.

[@WillPower311]

Yeah man. Probably as good as vw clean diesel...

[@ChipArgyle]

The K-cycle engine was able to do that decades ago. As the cylinders all rotated in a housing over a track rather than being attached to a crankshaft, each of the strokes could be of different lengths.

[@kyletrummel69]

"Check out this new engine." Yes. "It's a clever twist on the Atkinson cycle engine." Yes. "It was made by Volkswagen." NO.

[@larryl43]

Thank you

[@theodoremonroe6440]

From Volkswagen hmm did they just get caught for cheating?

[@isaiahspinney6113]

I’d imagine it pulls a bit of vacuum, must help the fuel atomize?

[@MejbiMajonez]

I don't want better efficiency, I want MORE POWER!

[@markbroad119]

You're also able to stick the oil vapor into the cylinders to keep lubed while keeping you on your toes about oil level

[@ChefBoyarDEEZ]

So it's like the opposite of skyactiv?

[@blackbusiness7]

Is less fuel injected in as well or does it run slightly rich?

[@willpugh8865]

Does this require any special parts? Or can this be programmed into existing engines software?

[@outcast_performance]

So does the vaccuum caused by more expansion help pull the piston during the first part od the comprrssion stroke?

[@nerainowen]

It is always a compensation balance between power vs efficiency. U want power, you go for more compression and fuel, if you want more efficiency, you go for more expansion ratio but at the expense of smaller combustion.

[@DerekKerton]

So you reduce the available power output for a given engine size, but you increase the engine's fuel efficiency. I like it. I can see why it wasn't a favorite until gas prices got very high, and CO2 started to be important to us.

[@R.A-117]

Where did you get the shirt from? It is awesome 😅

[@andrejs9112]

Bigger strain on rings? How long will those last?

[@Lovelessh3art]

If I'm understanding this right, it's more fuel efficiency at the cost of less power per stroke right?

[@For_What_It-s_Worth]

How is this different from running at part throttle? Same lower charge density. I suppose it is a reliable way to limit peak power charge density to prevent detonation while having a high compression ratio for its efficiency advantages. Effectively an asymmetrical stroke cycle.

[@bryaniskoo]

Does it also rapidly cool the intake air due to the vacuum?

[@bartoszskowronski]

I don't think it have any influence because it will compress to atmospheric pressure at the same time as in classical miller cycle intake valve close.

[@JohnJohn-zh4ov]

Yes it does cool the in-cylinder charge significantly prior to compression, it's been used for years. It's normally known as the miller cycle, which can have early or late valve closing.

[@joedad9999]

This would be great with variable camshafts where, when more power is wanted/necessary, the camshaft lobe could get a bit wider (or more accurately a wider camshaft lobe would be used) to open the valves longer

[@yassine-sa]

The weird looks pun at the end is pretty good 😂😂😂

[@Luka_3D]

You think they might use this in their range extenders?

[@mozeskertesz6398]

To be honest, this technology exists since at least the 20s. Some diesel engines used even more radical valve timing for coldstarting.

[@kofola9145]

Budack kicked in yo.

[@Raima888s]

Doesn’t closing the intake early increases resistance and reduces efficiency?

[@covoxer]

Not really. It's compensated on the way back, at the beginning of compression stroke. Intake stroke is harder, but compression stroke is lighter. So in general it's about the same.

[@YTsnatchedawaymyhandle]

So all you basically need is a cam with different profile and a ecu remap on a regular engine?

[@16scalerccars40]

Is it as clean as a vw diesel?

[@johnodei618]

But if you force it to go down with no additional air doesn’t this mean negative pressure? Isn’t this bad for the piston rings, in time oil may leak because of the wear?

[@Ricky-j8f]

So you drop the pressure in the combustion chamber. . .so what does that do to the crankcase pressure?

[@frayzenanimes9909]

How is the ratio of power longer if the piston will go the same distance in any kind of average explosion?

[@crazyoilfieldmechanic3195]

I always find it interesting when this type of thing is discussed because of the claims of improvement. Improvement needs to be defined. Improvement in milage ? Power ? Engine longevity? Almost any naturally aspirated gasoline burning engine will benefit from the valves opening farther and faster with the duration of opening matched to the compression, rpm range and intake and exhaust tracts of the engine. A maximum performance effort will always benefit from the highest opening and longest effective duration at the intended rpm range.

[@edwxx20001]

I believe the expectation is an improvement in MPG, which with volkswagen's track record would require a third party testing. The cycle would also come at the cost in engine power and longevity, all things being equal. A lower power eco mode, for idle and low intensity city driving. Although again, its not apparent HOW much more efficient it would be, or how much HP you would lose.

[@TheMrJackob]

Now I know why my old 2.0 tdi 16v burns so little fuel 😂 I not knowingly set exhaust camshaft about 2.5° earlier than intake cam when I was replacing timing belt.

[@fielddoktor4179]

This feels like the same idea as a reverser/cut off on steam locomotive engines. Pull the bar back and you put in less high pressure steam and let its expansion push you faster. And with greater efficiency

[@guitarlet300]

having a longer stroke makes it ideal for torque right? probably a good idea for a truck

[@Amin.Ashraf]

How about the 'power' of the combustion. The torque that rotate the crankshaft. Would it be less?

[@robertkesselring]

How is that fundamentally different from limiting intake air with a throttle plate?

[@GhostKoffee]

In other words, closing the valves early on the intake stroke kind of acts like a vacuum to give more power and force the compression and power strokes?

[@ShayeDeeeee]

That's a lot of words to say the cam timing makes it so there is less "suck" per "bang"

[@hypothalamusjellolap8177]

Recycling heat from the cylinder like an expansion valve to vaporize and chill. Perhaps allowing less cooling required.

[@simonlin9474]

cant u do the same if u make the vaule close late for compression?

[@commieTerminator]

What's the net energy efficiency?

[@BeanoNoir]

From a physics perspective, this can be less efficient as the crank case is always pressurized to a degree. By stretching the air charge, the absolute pressure is reduced in the cylinder. This will create a small degree of engine braking, increasing the parasitic loss during the intake stroke. This would be negated in a larger number of cylinders, but it would be noticeable in a 180 degree inline 4. Secondarily, due to the shorter intake cycle, the pressure at the plenum will be higher, which could also affect any systems relying on engine vacuum. This could necessitate the use of an additional vacuum pump, increasing mechanical losses. Now, if it is implemented in a turbocharged application, both of these issues will be negated when delivering boost.

[@frankbiz]

So if I run my car with a dirty air filter I will be doing the same thing right, less air?

[@anthonylipke7754]

I've heard it called early intake valve close Miller cycle elsewhere.

[@JmcGingerMan]

I'm sorry if this is noobish but since you can control the opening and closing of the valves anyways... Why not move the exhaust valve to the bottom of the piston cycle so that after the bang cycle happens the exhaust valve immediately opens and releases the gasses? Is it due to EPA? Also can gasoline be vaporized before being injected to increase the ultimate area that it is in before the bang cycle thus increasing efficiency?

[@michaeltaylor4613]

When do we get to see the emission ratings for these?

[@Berlintheking]

The never-cleaned intake air filter in my 4-year-old Mazda does the same thing.

[@Tony-ps9qk]

I need an engineer to answer the question. With the weak low tension rings they are running what are the chances of a vacuum situation causing more oil to burn (they already burn enough)....

[@KnightGravy]

Consumer here, when I step on the gas pedal does it convert cash to noise and make the vehicle go really fast?

[@CounterfeitDuck]

Every Turmoil player agreed with your shirt.

[@appomattoxross6751]

How about improving on GDI instead?

[@BobAbc0815]

So it is similar to a 5 Stroke?