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-   -   Atkinson cycle swap (https://www.fuelly.com/forums/f8/atkinson-cycle-swap-2591.html)

Sludgy 08-01-2006 05:22 AM

Atkinson cycle swap
With all of the engine swaps, has anyone thought of putting an Atkinson cycle engine in their car?

For example, the Toyota Prius head has Atkinson cycle cams and a high expansion ratio. Could it be swapped into a Corolla or a Yaris engine?

Likewise, the Ford Escape Hybrid 2.3 l engine has an Atkinson head. Could it be swapped into a Ford Ranger 2.3?

What about swapping the whole engine?

JanGeo 08-01-2006 06:21 AM

me thinks that the engine swap would require a starter added or you will be bump starting all the time...

GasSavers_brick 08-01-2006 06:26 AM

You could also try converting the existing engine to an atkinson cycle. It would be tricky depending on the particular application, but a DOHC motor could probably be converted with not much more than a custom or re-ground intake cam. Something tells me it would get more interesting with a SOHC engine since you wouldn't really be able to touch the cam without screwing up the exhaust timing.

krousdb 08-01-2006 07:13 AM

If i'm not mistaken, the Corolla uses the Atkinsonized 1.5 that is in the Prius. But I may be mistaken. Did I say that I may be mistaken about that? Someone else might want to check it out.

Sludgy 08-01-2006 09:35 AM

The Corolla uses a 1.8 liter. No mention of Atkinson cam timing, but its output of 126 HP is probably too high to be Atkinson. It does get great fuel economy, though.

The Prius has a 1.5 liter engine. Maybe the easiest swap would be into a Yaris. It too has a 1.5 liter engine, probably the same block.

thisisntjared 08-01-2006 06:12 PM

what is this atkinson engine?

SVOboy 08-01-2006 06:17 PM

We're not kewl enough. Is the insight atkinson? I forget!

Sludgy 08-02-2006 05:34 AM

Atkinson cycle

Originally Posted by thisisntjared
what is this atkinson engine?

The Atkinson cycle uses late intake valve closure (well after the piston has reached bottom dead center) to reduce the amount of air trapped in the cylinder.

This has two effects on efficiency:

1) At low loads where engine efficiency is poor, throttling/pumping losses are reduced.
2) It reduces the compression ratio to prevent knock, while keeping the expansion ratio high. Expansion is where the engine produces power, and anything that increases the expansion ratio improves efficiency. In a dedicated Atkinson engine, the expansion ratio can be increased while keeping the compression ratio low.


I suspect that Toyota and Honda's VVT engines may use Atkinson under some load conditions, simply because their FE is so good.

thisisntjared 08-02-2006 07:39 PM

hmm.... very interesting...

so how do you time the injectors?

Sludgy 08-03-2006 06:47 AM


Originally Posted by thisisntjared
hmm.... very interesting...

so how do you time the injectors?

Not sure about injection and ignition timing details of Atkinson engines. I suspect that nothing has to change when in closed loop operation, since the A/F ratio is constant at 14.5 to one. With low compression, I suspect ignition timing could be advanced more than a regular engine.

But only Toyota and Honda and Ford know for sure about each individual engine. I only know enough general info about engines to be dangerous.

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