Volkswagen's New Engine Cycle - The 'Budack' Cycle

How Does VW's New Budack Engine Cycle Work?

From the Volkswagen Tiguan Media Kit:
"The all-new 2018 Volkswagen Tiguan arrives in dealerships this summer powered by the most advanced version ever of Volkswagen’s EA888 four-cylinder engine. The updated version of the benchmark EA888 four-cylinder, turbocharged and direct-injection engine uses an innovative modification to the conventional four-stroke cycle to offer an improved combination of power, efficiency and responsiveness.

First introduced in the 2009 CC, the EA888 continued Volkswagen’s move toward smaller, turbocharged engines that offer the fuel economy benefits of downsizing with the power of a larger-displacement unit. Though EPA estimates are not yet available, compared with the 1.8-liter EA888 Gen 3 engine that is fitted in the current Passat, Jetta, Beetle, and Golf family models, the new 2.0-liter EA888 Generation 3B is expected to offer improved fuel efficiency along with a 20 percent boost in maximum torque to 221 pound-feet. The majority of the engine—from the cast-iron block to the aluminum-alloy pistons and cylinder head to the valve springs—has been updated along the way.

During development, engineers focused on making the engine more efficient in the range of driving that most customers use every day, which led to the introduction of a modified Miller combustion cycle that is unique to the Volkswagen Group. Whereas the traditional Miller cycle closes the intake valves just before the end of the intake stroke, the so-called Budack-cycle closes the intake valves much earlier. This results in longer effective combustion as well as faster air flow for the incoming gases, which improves the mixing of the fuel and air. The net effect is lower fuel consumption and more torque than the 2.0-liter EA888 engine fitted in the 2017 Tiguan.

The key feature that enables the new engine to produce better fuel economy, as well as excellent performance, is the variable valve timing system on the intake camshaft. Depending on engine load, it is possible to switch between short and long valve opening. At idling speed and under partial load, the valve opening is shorter. When the engine is placed under greater load, a switch to the camshaft lobe that opens the valve for a longer period is made and the driver can make use of the full power and torque of the engine.

The changes in the new version of the EA888 advance the twin goals of power and efficiency. The peak 184 horsepower (for the Tiguan) kicks in at 4,400 rpm, 400 revs sooner than in the 1.8-liter edition, and maintains its output until 6,000 rpm. Maximum torque of 221 lb-ft is achieved at 1,600 to 3,940 rpm. As in the previous 2.0-liter TSI® engines, the increased displacement comes solely from a longer piston stroke (92.8 mm vs. 84.1 mm in the 1.8 TSI), while the compression ratio rises to 11.7:1 due to a modified piston crown and combustion chamber. New TSI injectors can push fuel into the cylinder at a higher maximum pressure (250 bar or 3,626 psi), with up to three injection sequences per stroke depending on conditions."

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[starvalkyrie]

I like how these engineers are out here changing valve timing slightly and calling it a new cycle. Bow down before otto.

[steveman]

Koenigsegg be like: WIth our electronic valve control (Freevalve), you can have any cycle you want.

[doyouhavegainsonyourphone]

Doesn’t seem like a new cycle. If it was, every single engine that had different timing than another would be considered a “new” cycle.

[anguswett]

Everyone: floating a valve
VW: new engine cycle!

[Mr]

The "absolutely nobody will be able to fix it" cycle

[sganzerlag]

Very unimpressed. Since when does variable valve timing qualify as an entirely different type of cycle? Wtf.

[StopDropandLOL]

Sounds like the German thing to do.. make something inherently complex with completely average returns.

[eknaap]

The Budack cycle has one drawback compared to the Atkinson cycle: When closing the inlet valve before the piston reaches bottom dead centre, it creates a minor vacuum. That slows down the piston speed.

[bestleesinna]

sooo...VW made anti-VTEC. For all of you saying it's VTEC, you're wrong. The engine has LESS power than a normal engine running the Atkinson cycle, and then when you put your foot on the gas, it uses normal power. Anti-VTEC...a dark and well...not very powerful force.

[lohphat]

"Now with 40% less emission fraud!"

[AmaroqStarwind]

Something I'm particularly fond of is Freevalve technology, which uses pneumatic valve control to ditch the camshaft altogether. One of the greatest benefits of a camless design is that your engine can be fully programmable.

[shaind]

If this is coupled with supercharger or turbocharger, then this will benefit from having less intake resistance than conventional atkinson cam timing.

[dynamicsolution]

So the piston is pulling on a vacuum at the peak of it's stroke and this is advancement in engineering, good work vw!

[Alexsketchstudios]

To me this just seems like fancy variable valve timing

[daves]

Thanks for the quick/easy explanation of Budack!! Improvements, even when they don’t go to the top of class are still GREAT things!!

[loktom]

Having knowledge & experience of VW products from the past .
I am actually afraid of it.
No not the innovation folks.
It's the future repair BILLS.

[diegofianza]

“Shultz, these fuel efficiency numbers look awfully high on our new engine.”
“Herr Klink, I know nothzing! Nothzing!”

[xGolBLiiN]

“Can I borrow your homework?”
“Sure just change it a little”

[kurtisengle]

"Monkey Motion" The most reliable engineering you can buy. Thanks for the explanation.

27 mpg highway? SELL IT. While it still works.

[SpecialEDy]

My 1997 Plymouth Grand Voyager gets 27mpg highway with a pushrod 3.3L V6 that has 412, 000 miles on it. Im very unimpressed.