What exactly is the Budack Cycle? It’s a question you may have asked since news of an engine thus configured has surfaced. Named after one of its powertrain engineers, the Budack Cycle – developed by Volkswagen – is a variation of the Atkinson combustion cycle which is already commonplace in the market.
To recap, the Atkinson Cycle lowers the cylinder’s effective compression ratio by leaving the intake valve (or valves) open for a brief moment after the piston has started making its way back upwards from the bottom dead centre position, which means some of the intake charge is pushed back out from the combustion chamber before all valves are shut and the effective compression stroke begins.
This is relative to the cylinder’s expansion ratio (the piston’s downward stroke), which doesn’t change. In the case of the Budack cycle, effectively the opposite is done, which is to shut the intake valve before the piston reaches bottom dead centre, effectively reducing the compression ratio by reducing the amount of air-fuel mixture that is being pulled in before the compression stroke begins.
The goal in both approaches remains the same, which is to attain atmospheric pressure when the piston is at bottom dead centre. This of course is also in comparison to the traditional Otto combustion cycle, where the intake valves close when the piston is at or much closer towards bottom dead centre. In effect, this is variable valve timing of sorts, which trades outright power and torque figures for improved effiency.
In the case of the Volkswagen engine, it can also switch from the Budack cycle back to the conventional Otto cycle for maximum power and torque by a camshaft lobe which alters the intake valve duration. Watch the video above as Engineering Explained gives a rundown on the engine innovation.
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Hail the Toyota Mazda’s Otto Atkinson system.
Imitation is the best form of flattery.
And yet the fuel consumption for T & M generally still sucks… Why?
Blind bashers bash for nothing…
Honda SOHC iVTEC on R18/20 had this technology long ago. VW always claim first 10 years after la. Nissan made Superturbo in the 90s and VW made twin charge some 15 years after and claim they are first.
Chock-Hai – Japan always take technology from Europe la. Not the other way round. Chee sin!
How we know it truly works or isit another software magic thing again?
Good good we welcome this high techie engine…hopefully by this year hor..cant wait..
this is totally a copy from vtec system… vtec hv valve lift system which able to close early for low power and high fuel efficiency then open larger for high power… vtec kick’ed in yo~
Genius engineer detected. Any companies want to hire him? Malaysia has talent. Malaysia Boleh
Atkinson cycle invented by guy called Atkinson….does he sound Japanese….hahahahaha
Laugh so hard
So Parkinson disease is invented by Parkinson too? Time to use your brain.
Discovered bodoh. Discovered! Why does Toyota hire brainless people in sales?