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Chrysler to use Atkinson engines?

by David Zatz on

Chrysler will use an Atkinson-cycle V6 on its new minivans, according to reliable source oh2o.

The normal minivan will use a standard Pentastar engine, while plug-in hybrids will have an Atkinson-cycle version with an SI-EVT (Single Input Electrical Variable Transmission).

Mazda uses the Atkinson cycle in its SkyActive cars and Toyota uses it for the new V6 in the Tacoma. This would be the first Atkinson version of the Pentastar V6. Allpar’s “AutoTechnican” wrote,

Generally, for the Atkinson cycle, you raise the static compression (e.g. to 13-14:1), and hold the intake valves open into compression stroke. This effectively makes the power stroke longer than the compression stroke, allowing more energy to be extracted. If your valve timing system is flexible enough, you can make the engine dynamically switch between Otto and Atkinson.

Pentastar V6 engines

One challenge is the need for highly accurate fuel injection, which would be aided by direct injection. The timetable remains unclear on when the hybrid will actually be announced or released.

Mike V. added that pure Atkinson engines allow the intake, compression, power, and exhaust strokes of the four cycle engine to occur in one turn of the crankshaft.

With the Otto cycle, some pressure is left in the cylinder; in the Atkinson cycle, there is almost no remaining pressure in the cylinder, making it harder to pump fresh air into the next firing cylinder and  causing a power loss.

That’s why the Atkinson cycle is not normally used — a lack of low end power. They do, though work well with hybrid engines, which make up the gap with electric motors. Toyota has long used Atkinson cycle engines for their hybrid cars.  Full 2017 minivans page

David Zatz founded Allpar in 1998 (based on a site he had begun in 1993-94), after years of writing reviews for retail trades. He has been quoted by the New York Times, the Daily Telegraph, the Detroit News, and USA Today. Before making Allpar a full-time career, he was a consultant in organizational psychology. You can reach him by using our contact form (much preferred) or by calling (313) 766-2304


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