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Old 04-10-2014, 11:49 AM   #1 (permalink)
MetroMPG
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Location: 1000 Islands, Ontario, Canada
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Blackfly - '98 Geo Metro
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Toyota to use Atkinson cycle in non-hybrids: 10% efficiency boost, "no power loss"

Reports today say Toyota's going to start using Atkinson cycle engines in 14 non-hybrid models. They're starting in the Japanese market with 1.0L and 1.3L engines.

Quote:
The 1.3-liter engine will achieve thermal efficiency rates of 38 percent, while the smaller one delivers 37 percent. Higher efficiency means more energy from internal combustion is captured to power the wheels and less is lost through heat.

The outgoing engines have thermal efficiencies of 35 percent.

The new efficiency rates are on par with the 38.5 percent ratio achieved in the current engine of the Prius hybrid.
Atkinson is known for efficiency, but also low power/torque. They increased compression ratios to gain poiwer, and are carefully managing knock with 3 approaches:
  • new technology increases the combustion speed to consume more fuel before knocking can occur
  • scavenging and expelling unburned elements, so as not to overheat intake air
  • using a water jacket around the cylinder to regulate heat
Full article: Toyota unveils new generation of fuel-efficient gasoline engines

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