Print 65 comment(s) - last by superstition.. on Oct 19 at 12:54 AM

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 hpglow on 10/16/2013 11:55:51 AM , Rating: 2
My 2000 VW Jetta TDI just flipped 200k miles a month agao. That is with it pushing 24lbs boost up over the stock 17lbs for the last 100k miles. A well designed turbo engine is just as reliable if not over-built compared to its NA counterpart. The last GM car I bought seized after 140k miles. All my vehicles get their proper maintenance. Modern turbos aren't like the turbos of the past they are far more durable.

RE: According to whom?
By bobsmith1492 on 10/16/2013 12:18:32 PM , Rating: 2
And the turbo in my brother's 04 Jetta TDI died with around 100K miles just after he bought it. Point is a sample size of 1 is not very informative.

RE: According to whom?
By Devilboy1313 on 10/16/2013 3:35:41 PM , Rating: 2
If it died just after he bought it I see the problem. The last owner knew there was something wrong and wanted to pass on the problem to somebody who may not have taken it to a professional to be checked.

Min sample size should always be a diverse 50+.

RE: According to whom?
By Jeffk464 on 10/16/2013 5:21:22 PM , Rating: 2
its a bummer and expensive to fix on an old car. You can always open up the turbo and take out all the insides and put it back in. The car will run fine you just loose a lot of power.

RE: According to whom?
By Heidfirst on 10/16/2013 5:15:34 PM , Rating: 2
except that your 2000 VW isn't a modern turbodiesel ...
Modern turbodiesels have very high pressure common rail injection, DPFs, DMFs etc.. They may be more durable but they are less reliable because they are more complicated.;) & when the common failures occur in the UK you are typically looking at $1500 fixes.

RE: According to whom?
By superstition on 10/19/2013 12:54:41 AM , Rating: 2
That's nothing compared to the timing chain replacement with gears cost for the B5 Passat or the fuel system failure problem due to metal shards with the more recent CR VW diesels.

Bosch and the EMA in general warned, at least as early as 2008, that the lubricity of US diesel will cause premature wear. Their designs were not made for anything about 460.

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