Smarter minds than I, please chime in on the mechanics of this...

I don't think having a turbo automatically requires the vehicle to run on premium fuel. The actual factor for premium fuel is compression (and spark timing?). Doesn't Atkins+forced induction=Miller Cycle?

Also, there's currently NO VVT on the FEH (and sisters). The Atkins cycle is created by the specifics of the cam. Once again, others here will know the whole story and if I'm wrong.

Also, my research on the Ford Duratec line says that the engine design is based off Mazda's I4 2.0L , so if you're seeing this new type of motor already in a Mazda car then it's probably headed to the Ford platforms as well.

Smaller forced induction engine+PHEV, anyone? I'll be trading up!

 

Basically, yes, Atkinson + forced induction equals Miller cycle a la the Mazda Millenia. The CX7 doesn't use a Ford EcoBoost engine. It's a slightly de-tuned version of their turbo 2.3. It's in the Mazdaspeed 3 and was in the Mazdaspeed 6. It takes premium.

Walt makes a good point that you could use VVT to vary between Atkinson and Otto. But KenG nailed it that compression ratio limits it. I've always thought the FEH could be better with VVT and wondered why it's not included. Probably too expensive.

A turbo doesn't require premium necessarily. If it's for performance like Subaru's XT models, then it typically does.

Ecoboost basically combines variable valve timing, gasoline direct injection (see Cadillac CTS or VW's FSI engines) with light turbocharging in a very small engine relative to the vehicle's size. By tuning the arrangement for balance between economy & performance, output well over 100 HP per liter running regular is possible while still returning remarkable economy. It's cool to think a 2.0 liter 4 cyl is powerful enough (250++ HP) to perform well in a 2+ ton Ford Explorer. That's what they showed at Detroit this week.

For those interested: Lots of news is coming out right now. The Detroit Auto Show (this week) is a traditional time for American companies to announce their biggest news and breakthroughs. Surf some of the auto-oriented sites like jalopnik and autoblog or look at the big magazine's sites. Everyone's got reporters there and are posting updates constantly. It's an exciting week for those who like to keep up with the latest technology.

 

Actually, that's what you have now! Reading about this 10 years ago when the Prius came out in Japan was the "aha" moment that got me interested in hybrids.

Electric assist adds performance on demand to an engine tuned otherwise for economy. As such, adding forced induction on top of the electric assist is somewhat redundant.

It's a good idea, however, and could be awesome in certain applications. BMWs arrangements have two turbos, one small and one large. VW's got a European engine that is both supercharged and turbocharged so there is effective assistance at both low RPMs and at high RPMs.

 

I dont know why they call it an Atkinson engine other than the concept started with Atkinson. Atkinson implemented his engine with a variable crankshaft NOT VALVE TIMING. Miller used a conventional engine and changed the cam timing to accomplish a similar GOAL. Atkinson + supercharger does not = Miller. We have a Miller cycle engine without the supercharger but instead we use an electric motor for power assist.

Atkinson cycle motor http://www.keveney.com/Atkinson.html

 

This is true, which is why I qualified my own statement as "basically, yes Atkinson + forced induction equals Miller cycle a la the Mazda Millenia" and didn't get into a lot of detail.

This is also why I've often referred to the FEH engine as "Atkinson-like" instead of calling it "Atkinson" as Ford and Toyota and everyone else often does. You're absolutely correct that it's not really a true Atkinson setup as per the original patent and design.

There are some pretty cool animations and explanations on the internet of the real, actual Atkinson design for anyone interested. For the purposes of this forum I keep it fairly simple. Apologies if anyone was confused by that.

 

VVT as we know it does not change the duration. So, when the valve opening time changes, so does the valve closing time. That doesn't help much in optimizing the Atkinson cycle.

As Mark Smith said here, or in another thread, complete dynamic control of the valves would allow a great improvement in all areas of ICE performance.

 

Let me clarify, if I could get a 1.7L Turbo PHEV Escape... I'd be trading up in a heartbeat...

I was looking to the turbo to allow decreased overall engine weight (and rotating mass?) while maintaining current engine power. I would even expect increased performance over the naturally aspirated engine when higher RPM is needed and where the electric motor is already maxed out. This would addresses the issue raised about diesel engines scenarios and having two efficient low end torque providers when you really want the high end power from the ICE and the low end from EV.

<side note>

Back in 1987, GM/Buick had a 3.8L V6 turbo that out powered ALL of their other production performance engines and got far better FE. Talk about light and fast, I miss that Power6.

The thing I like about turbos is their non-parasitic nature. If you're not requesting boost, they have little drain on the engine output (and thus FE) but they are there in a big way when called into duty (OK, maybe there's a little lag).

It's sad that the most auto manufacturers turned away from forced induction in favor of larger engines. It seems forced induction fits perfectly with the general American public's demand for quick acceleration while they spend large amounts of time cruising at highway speeds needing much less power. I think several manufacturers agree with my assessment on the American driving style and this is the whole reason behind cylinder deactivation technology (anyone remember the 8-6-4 from the '80s Cadillacs?).

<end side note to prevent my further digression>

 

Yes, exactly.

I always thought it was kind-of a false advertising by Ford to call it simply "Atkinson".

What "Atkinson" did, and what Ford also claims, is to reduce the pumping losses inherent in an Otto 4 cycle gas engine.

 

I thought engine design changes like VVT were to allow a single engine to vary between operating at max efficiency and operating at max power. For our hybrids, we really want just max efficiency because the electric motor makes up for any extra power (torque) we might need when required. In other words, the extra complexity and cost of things like VVT would be wasteful on a hybrid. No?

 

This is a thread that really makes you think.

Is there anyone else here who has experience with the Ducati Desmo head engines? These engines have no valve springs. The valves are forced open with one cam and forced closed by another cam. (Valve lash adjustment is something of an art.) This design would allow independent adjustment of valve opening and closing.

Also, I think the discussion on the exact meaning of "Atkinson" is moot. Atkinson's original engine was a really strange thing. "Atkinson cycle" has come to mean any normally aspirated engine that has extended intake opening resulting in asymmetric compression and power strokes.