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Old 01-12-2015, 12:48 PM   #1
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Toyota new Atkinson-cycle engine

"2016 Tacoma will be powered by a 2.7-liter four-cylinder engine and a segment-first 3.5-liter Atkinson-cycle V-6 equipped with Toyota's D-4S technology, featuring both direct and port fuel injection."
Anybody knows what is "Atkinson-cycle" engine? Apparently it is new Toyota development and such engine can achieve 78 MPG
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Old 01-12-2015, 01:00 PM   #2
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http://en.wikipedia.org/wiki/Atkinson_cycle

Not new, just different.
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Old 01-12-2015, 01:10 PM   #3
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Old 01-12-2015, 01:32 PM   #4
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Not new. Will likely be a very slight increase in fuel economy.
They call it atkinson cycle but it only is in idea. Its just a matter of holding valves open longer. They have had VVT for a while now so it's not a big surprise.
I'm not looking forward to it.
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Old 01-12-2015, 01:35 PM   #5
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The rotary application would appear to have similar issues to the wankel in respect of rotor seals.
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Old 01-12-2015, 01:42 PM   #6
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There's a link in the first post. This is a conventional piston design. It's only Atkinson Cycle by virtue of what they're doing with the valve timing. The Wikipedia link I posted describes both styles of engine.

This is from the link in the OP.

Quote:
In order to achieve significant improvements in thermal efficiency, the Atkinson Cycle engines have been lavished with numerous innovations including a reshaped intake port, increased compression ratio, idling-stop, Variable Valve Timing intelligent Electric (VVT-iE) and a cooled Exhaust Gas Recirculation system (highlighted in image)
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Old 01-12-2015, 01:45 PM   #7
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Yawn. Call when when someone reveals a new Miller-cycle engine.
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Old 01-12-2015, 01:53 PM   #8
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Very similar to the Diesel cycle with similar efficiences but down on power. Used in many hybrids, maybe this is the precusor to a hybrid truck?
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Old 01-12-2015, 02:12 PM   #9
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Quote:
Originally Posted by motogon View Post
"2016 Tacoma will be powered by a 2.7-liter four-cylinder engine and a segment-first 3.5-liter Atkinson-cycle V-6 equipped with Toyota's D-4S technology, featuring both direct and port fuel injection."
Anybody knows what is "Atkinson-cycle" engine? Apparently it is new Toyota development and such engine can achieve 78 MPG
They've been using atkinson cycle engines in the prius for years.

They likely won't be using an actual atkinson cycle engine, they'll be cheating (As the do in the prius) and just making a normal Otto cycle engine with a cam that holds the intake valve open as the compression stroke starts.

Mazda had something similar - they called it a "miller cycle" engine. It held the intake valve open as the compression stroke started, but they had a supercharger on it.

EDIT: 205'ed by, well, everyone.
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Old 01-12-2015, 03:18 PM   #10
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My wife's '14 Avalon has one hooked up to/with the electric hybrid set up. It hauls asx and sounds like it is just revving away with a CVT. The hybrid Avalon is only .1 seconds slower in the 1/4 mile than the regular gas v-6. I haven't yet found a lack of power situation and 40 mpg. No fan belts at all on that car.
If the new Toyota will get 78 mpg, they won't keep 'em in stock.

From what I read a while back it does have something to do with the valves or valve timing as Donkey Hotey said or some sort of super magic to provide power and economy as a bonus.
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Old 01-12-2015, 03:24 PM   #11
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Originally Posted by Gillus View Post
From what I read a while back it does have something to do with the valves or valve timing as Donkey Hotey said or some sort of super magic to provide power and economy as a bonus.
High mechanical compression ratio to extract as much heat as possible from the power stroke, but delayed or extended intake valve timing to reduce the charge density so it doesn't ping itself to death from excess cylinder pressure. Easier to pull of now with direct injection, because it's just air being pushed back out the intake valve instead of air and fuel.
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Old 01-12-2015, 05:48 PM   #12
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Fail. Should have been a small diesel.
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Old 01-12-2015, 06:19 PM   #13
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Fail. Should have been a small diesel.
The problem in the states is diesel is too expensive relative to gasoline. You've got to a get serious mileage boost to make up for the $.50 to $1 gallon price premium diesel commands.
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Old 01-12-2015, 06:28 PM   #14
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My friend had a miller cycle mazda six from like 2001. That thing was a mighty piece of shit - no power down low and once it spooled up... still not much.

Pretty nice looking though.
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Old 01-12-2015, 07:13 PM   #15
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Originally Posted by motogon View Post
Apparently it is new Toyota development and such engine can achieve 78 MPG
In a 1L 3 cylinder it can. It's not going to get anything like that in the Taco
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