Atkinson's Cycle

Guess I am doing research after the fact because I have bought the truck.... But looking into the Atkinson cycle engine; it is kind of a neat concept. The intake and power stroke are different lengths for supposedly better efficiency. However looking at the actual fuel mileage people are reporting, it doesn't appear to be much, if any better than the older trucks. It appears to have a lot more moving parts and many more bearings. I am wondering if increased internal friction eats up the supposed efficiency gains?

 

But it has 7% more torque down low.... Yeah no Toyota dropped the ball in some ways... They need to tune more torque so people don't dip into the throttle as much.

 

This is why it is never a good idea to buy the first year of a new model... bugs need to be worked out!

 

Atkinson cycle will really shine on long highway drives with cruise control when the engine can remain in this mode for a long time. If you are constantly giving it gas, you are back in Otto cycle and the advantage is gone. In city driving you are mostly in Otto cycle which will not show much of an advantage. Any reports of long highway mpg?

 

Should not be the case at all. Every modern version of an Atkinson engine I've seen is done via ECU and VVT.

 

If that's the case the 4.0L has VVT and why not just program it to have "Atkinson cycle". I think the 3.5L has more moving parts to make it work

 

What is ECU & VVT. (I am not good with remembering acronyms). If VVT is variable valve timing, that is a neat feature that would obviously help the efficiency of an atkinson cycle, but how would that affect friction?

 

Yes sir you are so correct. Let the first buyers reveal all of the Tacoma 2016 bugs. I will wait till the 2017 come out and more than likely you will get a better deal. Keep test driving folks and provide us with all of the bugs

 

So if I'm reading this correctly it's possible for Toyota to make a programming change on the fly to reset the shiftpoints or Atkinson cycle if they feel the need based on real world feedback? Possibly during a scheduled maintenance visit without the need of changing any major?

When driving in the city we drive in ECT quite a bit. It has plenty of get up and go and no lack of power at all in this setting. It would be nice if Atkinson kicked in only when certain criteria is met such as above 45 mph and at a constant rate of speed for a certain period of time such as highway driving. Someone else mentioned this, but it would be nice if ECT was the default driving mode and the ECT button was actually an "Eco" mode.

We're satisfied with how it drives now, but making these subtle changes can enhance the driving experience and put the naysayers to rest.

 

ECT is tow haul mode.... always was, always will be. 2Gen dont have tow haul button but thats what putting in 4 does.
Driving constantly in ECT will probably wear the hell out of your transmission. Its not designed for. Its designed to run when you need to tow and you are not putting 12 000 miles on it.

 

Correct. Anything that is controlled by the computer can most likely be altered via firmware update. Takes some of the risk out of a 1st gen vehicle as they can make adjustments if needed.

 

Speculation at best. It just changes the shift points and running at a higher engine RPM (within reason) can actually reduce some of the strain on components. The existing shift logic is set for maximum fuel economy, not longevity.

 

Think the bugs need to be worked out of the 4 cylinder? I got cold feet on the V6 for that very reason.

 

If you read correctly, you'd see I just drive with it in the city. That's also not 100% of the time, just when I need some good get up and go. The shift points in ECT on the 3rd gen, are probably close to the same as the 2nd gen is normal and transmissions aren't falling out now are they? You're always looking for the gloom and doom angle, it's boring really.

 

You know, since you are so smart you should drive on 4x4 for extra traction, to go along with your extra power....

Most of you did not know what ECT button is couple weeks ago now you are expert and know transmission is build for it..

 

First off, I drive a 4x2, secondly I'm very familiar with ECT and what it does since I have a 2008 F250 with the same thing for towing and hauling. Leave now troll.

 

Hmm?? Yes, people criticize apple and other phone manufacturers. Apple especially for extreme dishonesty, where virtually every one of their "new inventions" or "new features" are actually stolen from somebody else. Its really pathetic, and people should be ashamed for supporting that.

 

FYI: It isn't actually an atkinson cycle engine. They are just partially simulating an atkinson through monkeying with the valves. I.e., the "short stroke" part of the atkinson cycle is simulated by holding the intake valve open through part of the compression stroke. It is *not* as efficient as an actual atkinson cycle engine would be, but most likely a heck of a lot smoother running.

 

Hold the phone! I was all confused. I looked up "Atkinson cycle" in Wikipedia. It showed the Atkinson Cycle to be a very complicated arrangement with the piston rod connected to the crank with complicated linkage to provide a different length stroke on intake and combustion cycles. Didn't look like a good way to make an efficient engine to me. I thought this is what Toyota must be doing. Doing further interweb searching showed me that Toyota approximates the same thing by simply leaving the intake open longer into the compression stroke on a normally designed engine to get the "Atkinson" cycle. Not nearly as big of deal,complicated or scary as I originally thought.

 

Yes, I have mentioned this in several threads as many people seem to think this engine is vastly different than the previous 4.0. The only real difference regarding "Atkinson" is that the:

4.0 Variable Valve Timing can change the intake cam angle by 50°
3.5 Variable Valve Timing can change by 80°

If that was the only difference they could have the same max HP and Torque numbers. I think the reason it feels weaker than expected has mostly to do with the programming of the new automatic transmission. No one knows what the torque curve looks like yet. Did Sweers says 90% max torque at 2000 rpm or am I imagining that?