Post your '16 MPG

The valve timing of the power stroke is indeed unchanged whether it's running the Otto or Atkinson cycle, but the T-s diagram of the power stroke is different depending on cycle. In Otto, the cylinder pressure is above atmosphere at BDC, but in the Atkinson cycle it's near atmospheric at BDC. That's why the Atkinson cycle is more efficient; it fully expands the power stroke, despite producing less specific power overall.

 

I get what you are saying, I just think "expands the power stroke" is misleading/confusing to anyone trying to understand what is going on. The engine isn't doing anything different during the power stroke; "Atkinson" happens only as a result of the intake valves closing very late.

BTW, when does it become "Atkinson"? 2GR-FKS can delay from 25-105° ABDC. 1GR-FE can delay from 10-60° ABDC. 5VZ-FE closes at 42°.

 

Exactly!

 

I forget sometimes that most people aren't familiar with thermodynamics terminology. "Fully expanding" the power stroke means that the Atkinson cycle extracts every bit of energy possible from the combustion gases. This is only possible because the effective duration of the intake stroke is so short (it sucks air in, then pumps a bunch of it out).

The Brayton (gas turbine) and diesel cycles are more efficient still, which is why airliners and locomotives, respectively, use them. Barring some major advance in battery technology, I think the next step in auto powertrain technology is serial hybrids powered by a gas turbine or diesel reciprocating engine.

 

Cool.

 

Thanks Sam; but, is it V6 4WD Auto or what?

Don't get me wrong, I am totally buying a 2016 soon; but, this just doesn't make sense to me. My 3.4 4WD Auto gets ~21 at 70 and ~20 at 75.

 

Planning any long distance freeway driving soon? It would be interesting to me to know what you are getting at 70 or 75 mph for 50-100 miles. I really hope THAT number is closer to 24.

 

I should be doing this over the next few days and can report back for you. I'm averaging in the high 19s in the city right now.

 

2X4 or 4X4

If people list their trucks in their profile, please add the drive config.

 

That is based on the trucks telemetry so far. I have driven approx 150 miles and almost used a quarter of a tank. And that's only having the truck for 150 miles, so I haven't been able to do the math yet.

 

2x4

 

Done

 

This is the picture I posted yesterday I think after only driven 100 miles in the car. I'm in suburbia so I think "city" is inaccurate, but I do deal with a good bit of stop and go. Just have to be gentle withe the throttle.

 

Once I leave work I'll snap another picture of today's numbers along with the fuel gauge reading.

 

And you already have people saying they are exceeding those figures on the highway

 

What's the terrain like where you are though? That could be the difference. It's not too hilly where I am.

 

Honestly I didn't even look to see what mine says, but I'll look when I leave. It's still in the back seat.

 

With our 2nd tank of gas, we're averaging 19.6 in the city with a 4x2.

 

We are limited to 60 here, but I still run 70 on the highway

 

Yeah and I'm still getting passed at that speed lol