Volkswagen's New Engine Cycle - The 'Budack' Cycle
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Have you guys heard of this?
https://www.youtube.com/watch?v=JjM14JBPdBI According to this, the 2017 gets 20/24 and the 2018 will be rated 24/30. How much of that is from the Budack Cycle? "the [2.0-liter] engine will provide `1.8-liter power with 1.4- to 1.5-liter efficiency.'” http://ecomodder.com/forum/attachmen...1&d=1506002103 VW's New 2.0L Turbo is More Efficient, More Powerful and Runs on Regular Gas » AutoGuide.com News |
Interesting, they're closing the intake valve early on the intake stroke vs leaving it open longer on the compression stroke. It seems like the Atkinson cycle would still be superior for efficiency purposes as it would reduce pumping losses more than the Budack cycle. However, there isn't air/fuel going back out the intake valve which is a nice thing. Overall I bet the differences between the two are negligible. Therefore it probably comes down to whatever is easier/cheaper to manufacture.
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Which cycles require licensing? That would affect manufacturing cost, right?
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Just another trick to emulate the Atkinson effect in an Otto engine, given a different name for marketing reasons. I could guess the intention of naming it as a new cycle might be also an effort to whitewash Volkswagen's reputation in the post-Dieselgate era.
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It sounds more like the difference between six and half a dozen.
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The Fiat MultiAir had early intake valve closing in one of it's modes of operation.
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Also, because you end up with a piston creating lower pressure in the cylinder with the remainder of the downstroke, you're depressurizing the air and may actually be pulling heat out of the cylinder walls, rather than losing it into them, which would be a net thermodynamic gain. |
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This is why cylinder deactivation works better if you close all of the valves, rather than leave them all open. Open, and you're doing the work of pushing air through the valves. Closed, and although you're compressing the air, after TDC that compressed air gives its energy back to the piston. |
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