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Larger displacement Atkinson cycle engines may be in the future for Toyota

A number of automotive manufacturers have begun to move away from larger displacement naturally aspirated engines to smaller displacement turbocharged engines. The general idea was that smaller and lighter engines would use less fuel while offering the same sort of performance thanks to the addition of a turbocharger. However, in the real world many drivers have discovered that turbocharged small displacement engines are often unable to deliver on their fuel efficiency claims.

Toyota is considering bucking the industry trend and rather than going with smaller turbocharged engines, is considering larger naturally aspirated engines to improve fuel efficiency. Senior managing officer in charge of drivetrain R&D for Toyota Koei Saga recently said that Toyota believes gasoline engines could benefit more from upsizing capacity in conjunction with Atkinson combustion cycles than going smaller with turbochargers.
Atkinson engines today are typically only used in hybrid vehicles like the Prius, Ford Fusion Hybrid, Hyundai Sonata Hybrid, and Honda Accord Hybrid.

Toyota Camry
Increasing the displacement of an engine using the Atkinson cycle would deliver a specific output less than that of similarly sized conventional combustion cycle engines, but fuel economy would be better. Toyota believes that fuel economy would be better than the smaller engines they replace.
Toyota has offered no timeframe for bringing larger displacement Atkinson cycle engines to market and hasn't hinted at which models might get the Atkinson cycle engines.
Mazda experimented with similar “delayed valve” Miller Cycle technology over a decade ago in the Millenia midsize sedan. But instead of using electric motors to make up for the reduced power density like today’s Atkinson-engine hybrid vehicles, the Millenia used a supercharger.
Saga also talked a bit about the next generation Toyota Prius saying that the vehicle will use a mixture of battery technology including lithium-ion and nickel batteries. The reason for mixing battery types is that lithium-ion batteries are better for performance, but the durability and lifespan is better for nickel batteries. 

Source: Green Car Reports

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It's All About Torque
By Stiggalicious on 10/16/2013 10:51:28 AM , Rating: 2
After switching from a naturally-aspirated to a turbo engine, I will never buy a car with a naturally-aspirated engine ever again. Turbocharged engines that are designed well (like Ford's 2.0T in the Focus ST or the VW/Audi 2.0T) have oodles of low-end torque and almost no turbo lag whatsoever. They turn the cars they're put in into highway overtaking monsters. They last just as long as any normal NA engine* and weigh less. I would much rather have a 1.0T that delivers the same power (and probably more low-end torque) as a 2.5 Atkinson cycle engine. It may sacrifice 1 or 2 MPG, but it makes up for it by reducing the weight and size of the engine significantly (enabling better handling, acceleration, braking, and lower rolling resistance from the tires).

*About the lasting-longer part: If you drive 3-4 miles per day for your commute and don't get your engine and oil up to temp, then yes a turbocharged engine will die sooner. However, nowadays the engine will still outlast the rest of the car since the car tends to wear out and break pretty much everything else by the time 250,000 miles/15 years comes around. Sure, a Crown Vic NA V8 can last for 600k miles no problem, but nearly everyone gets rid of their car by the quarter-million-mile mark.

RE: It's All About Torque
By chromal on 10/16/2013 4:56:44 PM , Rating: 2
I feel the same way, plus I live in Colorado and drive between 5500ft and 12000ft elevation. Did you known that naturally aspirated engines lose 3% of their max horsepower for every 1000ft above sea level that they're driven? This starts to matter when you live at 8700ft and need to literally climb mountains. Turbocharged engines make for a happy engine in Colorado.

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