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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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RE: According to whom?
By BikeDude on 10/17/2013 5:51:16 AM , Rating: 2
Make sure you compare apples to apples.

If you choose a V6 NA over an inline 4-cylinder turbocharged engine, you might get the same performance, but...

Make sure the larger engine is still maintainable. A colleague of mine was charged an excessive amount of money to replace a simple thermostat on his VW Passat (w/V6). It is so difficult to gain access to the thermostat so what should be a simple procedure becomes a very complex operation. Unless you enjoy doing such jobs yourself, you might not be saving the kind of money you think you are.

I've replaced the thermostat on my Saab 9000 2.3T myself. It is a much faster car than my colleague's VW and the thermostat was easily replaced.

The turbo isn't that hard to replace either. I got my dad a second hand low-mileage turbo for $200. Still less than what my colleague paid for that thermostat.

As for fuel economy: Yes, the faster you get up to speed, the sooner you run the risk of having to slow down. Every press of the boring brake pedal means a loss of energy, so faster will always be more expensive. However: I have the choice every time I ride my car. And I can accelerate out of potentially dangerous situations.


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