2GR-FKS more 'Atkinson' than Prius.

I had been wondering just how "Atkinson" this new engine could be... I figured: not very; it's mainly marketing talk (especially considering the MPGs turned out to be not too impressive.) But according to the spec sheet I found, the VVT-iW on the 2GR-FKS can close the intake valves three degrees later than the current Prius 2ZR-FXE!

It can delay intake valve closing until 105° after bottom dead center. Wow! That means it can use about half the air of a normal engine. So, it should use about half the fuel at idle, right? Why not better MPGs? Seems like there should be a huge MPG benefit somewhere. (BTW: I wish EPA would amend their stickers with a chart or graph: it gets this MPG@45mph, this MPG@50mph, etc.)

http://www.toyotareference.com/guts/tacoma16_engine.pdf

 

Prius also idles using the electric motor, not the engine about 95% of the time

 

To be clear, I am not trying to say the tacoma should get prius mpgs. I am just saying it can go legit atkinson which makes me think it should easily get better mpgs than, say, the GM twins.

 

My Atkinson is bigger than yours.

 

I will get better mpg than the GM twins. I drive slow

 

I'm guessing power to weight and aerodynamics..

 

The combination of Direct Injection plus Atkinson cycle might improve efficiency 10-15% over a port-injected Otto engine of the same displacement. But if the truck is heavier and aero wasn't improved significantly, this doesn't translate to a big difference in real-world fuel economy.

When Mazda switched from port-injected Otto to DI Atkinson, their highway MPG soared from 31 MPG to 37 MPG. However, this was accompanied by big weight loss, massively improved aero, a taller/more efficient transmission, stop/start, etc. Compared to Mazda, Toyota only performed a half-measure by improving the engine and transmission without reducing weight or improving drivetrain efficiency elsewhere.

 

Watch. The Tacoma will have greater or equivalent real-world MPG as the GM twins.

 

Note that Toyota did significantly improve aero. Coefficient of drag was reduced by ~8%.

 

I'm not convinced this wasn't "achieved" primarily by foisting the tonneau cover on dealers; they have a quota that the majority of TRD/limited models have to have it. The published specs apply to the "most common" configuration.

Also note that Cd is pretty meaningless on its own, it's Cd*A*Q=drag force. To me, the new grille looks like it has more frontal area.

 

2016 Tacoma....18 city, 23 highway
2015 4Runner....17 city, 22 highway
2015 Taco..........16 city, 21 highway

So, the 4Runner is heavier and shorter, two distinct advantages for the a Taco as longer vehicles have significant advantages.

The taco has Atkinson cycle, direct injection, dual VVT, six speed, the latest aerodynamics......all designed to increase economy,

The 4 Runner has an 11 year old motor from the same family with dual VVt, the only up grade over the old Taco motor and has the older 5 speed. Please, someone explain to me why the word "hype" doesn't come to mind. The 4Runner has similar HP and torque numbers at a significantly lower rpm.
The new Taco should be quieter and ride and handle better. Other then that, I am at a loss to figure out what all the excitement about this freak'n motor is about. The trans mission improvement alone will improve mileage by one to two...

Maybe, actual mileage will be different. . Guess I am dreaming. Atkinson cycle ? Wtf cares.......

 

BTW, today is the press day for the 2016 Prius. Much like our press day was Aug 17th. I know all of you are so jazzed for the new Prius.

 

this.... I had a Focus and I got less MPG then they estimated. I now have a Tacoma and I get higher MPG than should be possible (21) with a lift and 285/70R17. I think GM/Ford over inflate and Toyota is conservative.

Carl

 

EPA testa are quite different then real world mileage. A lot of vehicles don't get close to advertised mileage. While others will match or beat advertised mileage. Let's wait and see before making any judgement.

 

I think overall the EPA figs have become pretty accurate. More so on the highway than city. If you live in a small city, you will get worse city MPG for gas cars. That's because you probably don't hop on the freeway to cross town, you stop at a lot of lights, and your engine doesn't have a chance to get fully warmed up. I get shit mileage in the city but I get EPA or better on the highway.

 

Indeed; the 4.0L 4x4 Tacoma beats the 2.7L 4x4 F150 on Fuelly by 1 MPG or so, despite a 2 MPG deficit in the EPA combined ratings. Real-world of the 2016 3.5L 4x4 will probably be 20-21 MPG combined. New Colorado is averaging ~19 MPG combined on Fuelly.

 

I would guess the new engine design is more for meeting EPA emission standards than anything. They still have a long way to go to get a motor that exceeds efficiency standards along with emissions. European standards call for so much power per displacement as well as emissions and they build engines around those. Here in the U.S. we build an engine and then add a bunch of crap to try to make it comply, resulting in shit. Toyota seems to have adopted this theory.

 

I think it is also interesting to note that the FKS didnt bring much of an improvement to the lexus GS.....1mpg improved highway and combined for the AWD GS350, but then a 1mpg improvement only city (no improvement highway/combined) for the RWD GS350: http://kaizen-factor.com/from-fse-to-fks-the-evolution-of-toyotas-2gr-3-5-liter-v6/

Is incremental improvement like that enough to hit their CAFE targets?

 

New motor is complete BS just like a Seatbelt bracket Mike's statement about drum brakes being great for off-roading.
The only place that atkinson cycle can run and save any fuel is idle. Who the F idles that much. Yes if you caught in traffic jam than you will save 0.0001MPG, otherwise there will be always demand for power greater than the minimum of the air-fuel mixture (its a small car engine after all). Now if that engine was in the 2000Lb Camry than yeah idle and some highway driving.
However, whatever you save through Atkinson cycle will be blown away by Injectors cleaning cycle than can last up to 10 minutes. Thats a 10 minutes of dumping extra fuel..
Real life MPG may be way worse than 1GR .. especially when somebody is trying to tow with that thing.
It looks like Biggest savings in MPG for highway come from improved aerodynamics, but hey if somebody wants they can install the stupid airdam on 2gen truck with tonneu cover and claim same aerodynamics.

 

Wrong.

Injector cleaning cycle? Where do you get this crap?

I predict wrong again. Go fear monger somewhere else.

OP, Atkinson cycle saves gas by burning it more efficiently, not by burning less of it. The compression stroke is designed to allow just enough gas into the cylinder so that when it combusts, the resulting air pressure in the cylinder at dead bottom of the expansion stroke is equal to 1 atmosphere, ie all of the potential pressure generated by the combustion is used up and there is no remaining pressure that is wasted.

In the Otto cycle, when the gas is combusted, the pressure is much greater than in an atkinson cycle engine, however, at the bottom of the expansion stroke there is a lot of unused kinetic energy as the resulting pressure in the cylinder is much greater than 1 atmosphere at dead bottom of the stroke (ie, it still wants to force the cylinder down further but can't as the cylinder is at the end of the stroke). This extra pressure (ie energy) is wasted out through the exhaust.

Atkinson cylce will see better MPG's across the spectrum than otto cycle, at the expense of power. In the 2GR, expect to see MPG savings when ever you are not accelerating.