What is the Budack cycle?

By Product Expert | Posted in FAQs, Fuel Efficiency, Technology, Volkswagen Innovation on Thursday, June 25th, 2020 at 5:07 pm
Close-up view of the machinery inside a car engine

Budack Engine Cycle Explanation and Definition

Volkswagen is continually innovating, whether with design, technology, or mechanics. One impressive innovation they’ve created is a new type of engine cycle that bestows unique benefits on their vehicles. This is referred to at the Budack cycle. What is it?

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The Budack cycle is a new version of the Atkinson engine cycle. It was created by Volkswagen to provide its vehicles with a more efficient combustion process and improved fuel efficiency. The Budack cycle also provides the driver with more power at-the-ready when they press down on the throttle.

Benefits of the Budack cycle can be seen on the Volkswagen Tiguan.

How does the Budack cycle work?

To understand the Budack cycle, we first have to take a few steps back to look at the basic automotive engine cycle. This standard cycle is called the Otto cycle; it’s made up of intake, compression, combustion and exhaust.

A step beyond the Otto cycle is something called the Atkinson cycle. The Atkinson cycle involves leaving the intake portion of the 4-stroke process open a bit longer than the Otto. As a result, this process carries over into the compression stage. The engine compresses some of the air in the piston chamber out, which lowers the compression ratio. By doing this, the Atkinson cycle allows for a more efficient combustion stage.

The Budack cycle created by Volkswagen also alters the timing of the intake valves. However, instead of leaving the valves open for a longer period, this cycle closes the valve earlier than on a standard engine. The result is a lowered compression ratio. While this means that less power is created, it also means the engine maintains a more efficient combustion process and improved fuel efficiency.

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Does the Budack cycle make an engine less powerful?

Though the lowered compression ratio brought about by the Budack cycle does result in less power, it also bestows higher variable valve timing on the vehicle. This means that the driver will experience more power at-hand when they press down on the throttle. The intake valve timing moves to a standard cycle, with the result being that one gets more power when they want it.

In this way, the Budack cycle-equipped engine switches between operating cycles depending on whether the driver indicates a greater need for power or fuel efficiency via their throttle input.


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