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Atkinson Cycle Engine

AriLea

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So anyone with better info on this, jump right in, please, be my guest!

The Atkinson(link) cycle engine Toyota is developing for their Aygo car, is claiming it will get 78mpg.

As only a 1 liter engine, this is similar to the Elio engine class. I haven't got solid conclusions on the US vs the euro mpg, but (loosely speaking) it appears that the current US Aygo is in the 50's(mpg) and the euro is up as high as 68mpg. Although this euro-metric may be a miss-quote for the measurement scale used. Like maybe k/gal?

So given the suppositions above, the new engine maybe as high as a 15% improvement(?is that right?) over the comparable current Aygo engine. Assuming the current Aygo engine tech is equal to the Elio tech, an Elio type autocycle design using the Atkinson technology could get (84 x 1.15) = 96.6mpg.

It's doubtful Toyota would enter into the Elio class market, at the Elio pricing, until real-world marketing performance data is collected. But if it did, and kept to the tight Elio pricing structure, it could definitely give Elio a run for it's money. So that is only a possibility after the first Elio Year 3's hit the showrooms.

On the other hand, if the Atkinson engine costs substantially more to produce, then they can't keep the vehicle down to an Elio competitive level. That same kind of issue eliminates both hybrid and EV tech as direct competition to the Elio, since that would push those products to a different class of buyer.

I have to add however, if you value the extra MPG at $100 per mpg per $1 in gas pricing, as often I do, then at $3/gal a 97mpg vehicle at $10,700 is a direct equal to a $6800 Elio for my financial decision making. With gas down to $2/gal I calc that out to $9400 as equal competition. Not every person does that kind of calculation, unless the bank drives them to it.. lol

Note: Atkinson theory can be added retroactively to existing engines with between moderate to heavy modifications. This is an option Elio could take in the future, if need be.
 
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skychief

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... if you value the extra MPG at $100 per mpg per $1 in gas pricing, as often I do, then at $3/gal a 97mpg vehicle at $10,700 is a direct equal to a $6800 Elio for my financial decision making. With gas down to $2/gal I calc that out to $9400 as equal competition. Not every person does that kind of calculation, unless the bank drives them to it.. lol
Note: Atkinson theory can be added retroactively to existing engines with between moderate to heavy modifications. This is an option Elio could take in the future, if need be.
Wow. that's overthinking it a bit. :D
It's doubtful Toyota would enter into the Elio class market, at the Elio pricing, until real-world marketing performance data is collected. But if it did, and kept to the tight Elio pricing structure, it could definitely give Elio a run for it's money. So that is only a possibility after the first Elio Year 3's hit the showrooms.

IMO, Toyota cannot possibly enter the Elio class market, at the Elio pricing. Because Toyota uses a completely different business/marketing model than EM. They could never produce a new vehicle and sell it for under 8 grand. Toyota is no threat to EM.

Its important to note that the Atkinson-cycle technology gets its efficiency at the expense of horse-power-vs-displacement. So if this technology was implemented in the Elio engine, and the displacement (900 cc) stays the same, you can kiss 55 HP goodbye.

IMO, EM already has a good formula for power/economy/cost/practicality/function. They should be in a class all their own... At least until some other auto makers make drastic changes to their business model.
 

Cjr

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The Atkinson engine is in current use in Toyota (Prius) and Ford (Cmax, Fusion) hybrids and plug-in hybrids. To have an Atkinson engine of this design requires 1) 4 cylinders and 2) electronic/electrical valve control/actuation instead of a camshaft. Both requirements would increase the cost of the engine substantially.

The Atkinson cycle engine (https://en.wikipedia.org/wiki/Atkinson_cycle) gets better fuel economy by varying its effective displacement. James Atkinson's original 1882 design did that with a complex mechanical design. Modern Atkinson cycle engines use variable valve timing to generate the increased power stroke expansion that yields better fuel economy.

Relative to power vs. fuel efficiency, the 2 liter 4 cylinder Fusion Atkinson engine variant gets about 140HP or 70HP/liter. The Elio 0.9 liter engine gets 55 HP or 61HP/liter. Although it is true that a power penalty is associated with an improvement in economy, the Elio engine design has already paid that penalty in its design. The primary issues are increased complexity and the costs associated with it.
 

Coss

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... and I'd like to see this one!

That motor looks like a mechanics worst nightmare; oh that's right, we don't have mechanics any longer, now they're Service Technicians.

But can you imagine that much mass, and that many moving parts at high revs; that if something decided to have a bad day and come apart internally what kind of destruction and horrible noises that motor would make?
You would have to just pull it out, and toss it in the scrap metal pile to be melted down.
 
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Ty

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That motor looks like a mechanics worst nightmare; oh that's right, we don't have mechanics any longer, now they're Service Technicians.

But can you imagine that much mass, and that many moving parts at high revs; that if something decided to have a bad day and come apart internally what kind of destruction and horrible noises that motor would make?
You would have to just pull it out, and toss it in the scrap metal pile to be melted down.
It wouldn't be easy to rebuild. That's for sure. I like that instead of having the connecting rods ride around the crank, there is an intermediate lever that rides the crank. By simply moving the far pivot point, you change how high the piston goes. That is a simple way to change the compression ratio. I reckon that's easier than having the whole head move up and down. Maybe a button in the head that is normally flush but when you want a higher compression ratio, it extends into the combustion chamber slightly. Hmm...
 
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