wemay
Site Donor 2023
...and if "more efficient", why isn't it used in more models?
What makes an engine an Atkinson Cycle engine
- Thread starter wemay
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wemay
Site Donor 2023
Hahahaha! That post wins the day!
wemay
Site Donor 2023
Originally Posted By: DriveHard
http://bfy.tw/AcP2
Here...let me Google that for you...
Did that. Wanted something more layman's. Thanks for the Google tutorial.
http://bfy.tw/AcP2
Here...let me Google that for you...
Did that. Wanted something more layman's. Thanks for the Google tutorial.
it's a more efficient cycle but you lose power density. If you were to have a pure Atkinson cycle engine in your car it would feel sluggish and no one would want to drive it. To bring the power up to an acceptable level you would have to increase the size of the engine and thus lose the efficiency gains. The sweet spot for these engines are low load points such as cruising at a steady speed. Toyota supplements the acceleration portion with their hybrid system and Mazda goes between the Atkinson and standard cycles as needed.
Go drive a skyactiv car and learn to feel the difference. If you drive very gently and stay in the Atkinson realm you'll get great fuel economy. However, if you just tip into the standard range fuel economy fallls off a cliff.
Go drive a skyactiv car and learn to feel the difference. If you drive very gently and stay in the Atkinson realm you'll get great fuel economy. However, if you just tip into the standard range fuel economy fallls off a cliff.
wemay
Site Donor 2023
Originally Posted By: 09_GXP
it's a more efficient cycle but you lose power density. If you were to have a pure Atkinson cycle engine in your car it would feel sluggish and no one would want to drive it. To bring the power up to an acceptable level you would have to increase the size of the engine and thus lose the efficiency gains. The sweet spot for these engines are low load points such as cruising at a steady speed. Toyota supplements the acceleration portion with their hybrid system and Mazda goes between the Atkinson and standard cycles as needed.
Go drive a skyactiv car and learn to feel the difference. If you drive very gently and stay in the Atkinson realm you'll get great fuel economy. However, if you just tip into the standard range fuel economy fallls off a cliff.
Thank you. That was what i was looking for to a tee.
it's a more efficient cycle but you lose power density. If you were to have a pure Atkinson cycle engine in your car it would feel sluggish and no one would want to drive it. To bring the power up to an acceptable level you would have to increase the size of the engine and thus lose the efficiency gains. The sweet spot for these engines are low load points such as cruising at a steady speed. Toyota supplements the acceleration portion with their hybrid system and Mazda goes between the Atkinson and standard cycles as needed.
Go drive a skyactiv car and learn to feel the difference. If you drive very gently and stay in the Atkinson realm you'll get great fuel economy. However, if you just tip into the standard range fuel economy fallls off a cliff.
Thank you. That was what i was looking for to a tee.
The short version is the compression stroke is shorter than the power stroke.
With the proper setup, I'd think an engine could move pretty well between these modes and be able to get good low-end torque when needed, good high-end HP when needed and excellent FE when cruising. I would think such an engine would need a small turbo charger (fast spin-up) to prevent/reduce perceived "turbo-lab" and very well controlled CVVT of both intake and exhaust timing/duration/lift.
The Koenigsegg's Wild Freevalve Engine comes to mind here.
The Koenigsegg's Wild Freevalve Engine comes to mind here.
Originally Posted By: RedOakRanch
The short version is the compression stroke is shorter than the power stroke.
How is this wondrous event performed?
The short version is the compression stroke is shorter than the power stroke.
How is this wondrous event performed?
Originally Posted By: andyd
Originally Posted By: RedOakRanch
The short version is the compression stroke is shorter than the power stroke.
How is this wondrous event performed?
In a modern Atkinson cycle engine? Variable valve timing.
Originally Posted By: RedOakRanch
The short version is the compression stroke is shorter than the power stroke.
How is this wondrous event performed?
In a modern Atkinson cycle engine? Variable valve timing.
Originally Posted By: Bottom_Feeder
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Good one!
Good one!
edyvw
$50 site donor 2026
Drove new Highlander few days ago with their Atkinson cycle engine. It is OK, but power is at very high end of rpms, which is really not best solution for an SUV.
Although it makes bit more torque then older engine at same rpms (4700), older engine felt bit more powerful at lower rpms.
Although it makes bit more torque then older engine at same rpms (4700), older engine felt bit more powerful at lower rpms.
Originally Posted By: Bottom_Feeder
?
someone beat me to it! But I knew someone was going to post Mr. Bean
someone beat me to it! But I knew someone was going to post Mr. Bean
Originally Posted By: 09_GXP
Go drive a skyactiv car and learn to feel the difference. If you drive very gently and stay in the Atkinson realm you'll get great fuel economy. However, if you just tip into the standard range fuel economy falls off a cliff.
I don't know. I drive mine HARD most of the time and my fuel economy still shows a combined number of 34. That's with an average speed of 37 due to all the traffic I am stuck in as well as all the traffic signals I sit through.
Go drive a skyactiv car and learn to feel the difference. If you drive very gently and stay in the Atkinson realm you'll get great fuel economy. However, if you just tip into the standard range fuel economy falls off a cliff.
I don't know. I drive mine HARD most of the time and my fuel economy still shows a combined number of 34. That's with an average speed of 37 due to all the traffic I am stuck in as well as all the traffic signals I sit through.
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