Do we really need more speeds than a six speed auto trans

No, actually I do not believe it to be a ratio or spacing issue except as dictated by the practical constraints of using a relatively low power engine¹ to drive a relatively heavy vehicle.

I suspect Toyota's engineers spent a lot of time determining, hand-wringing and lamenting, what ratios and spacings would find their way into production--certainly they knew the engine's overall characteristics were inadequate to what many would expect in a mid-size pickup truck--and they did the best they could.

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¹- Apparently the "global community" has decided that 3.5 L is as big as an engine needs to be for all but the heaviest applications--of course that is enormous compared to the "big" 2.4 L 4-banger World Gasoline Engine standard being boosted by the Global Engine Alliance.

 

What would that "proper gearing" be?

Here are the existing ratios--what would you change to make it better...



I know what I would change...

 

I swear on my life if Toyota puts a CVT in either the Tacoma, Tundra, 4runner, or Sequoia, I'll torture every executive and design official with daily 0w-30 chugs, branding them like cattle with a metal Toyota symbol, and make them drive a 16-17~+~ auto 3rd gen for the rest of their lives (let's hope the 18 fixes some major issues...)

 

Very little difference...

 

I would not change anything except for 5th an 6th. As it stand 3.90X.58=2.26 gear ratio. That does not count for larger tires. I would bump 5th to .78 an 6th to .70 which would be a 2.73 gear in 6th. If lower RPMs were needed for interstate fuel mileage. Then I would change gear ratios in both ends which probably would not be much.

 

i couldn't imagine our trucks with a 5 speed. Obviously they would have to be geared differently. Anyways the problem isn't with the tranny itself. It's the programming. Obviously they want to try and get the most fuel economy. The programming was crap. Better after the TSB but still not perfect but that won't change because of the gear ratios in the rear end. If you haven't had the TSB done try that and see what you think

 

I think the transmission would work better if the truck was tuned for better low end torque. Ovtune has been working on some stuff. Or maybe but doubtful Toyota will have a reprogram of the ECU. My wife's 2011 highlander feels stronger off of idle then my truck does. Better tuning with more torque at around 2000rpm will help the truck downshift less on the highway.

 

The fundamental problem is with the 3.5 L engine's torque delivery¹--here are Toyota's charts for the 1GR-FE and 2GR-FKS (note that both the vertical and horizontal scales differ, making simple visual comparisons challenging, however the differences in the torque curves are quite clear):



The 1GR engine's torque output has a near linear upward slope from 1000 (220 lb·ft) to 4000 rpm (266 lb·ft)--this is desirable for the sort of "low end" drivability one would expect in a truck.

The 2GR engine however delivers only 180 lb·ft at 1000 rpm, struggles to 260 lb·ft at 2600 rpm then dips and recovers to 260 lb·ft at 4000 rpm where it continues to climb to its peak--this explains the "you need to put your foot in it" advice offered by many; and why the tranny hunts for the proper gear at lower engine speeds--throw in the "Atkinson" mode and what you have is not a truck engine...

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¹ - The 2GR is what we old timers would call a "cammy" little engine--great output for it's displacement and probably fun on a race track, but around town you need to "drive it like you just stole it" to make it impress onlookers.

 

Low end torque is the issue--see my post above, if it can be improved with tuning it would fix a lot...

 

Yup. If they reprogrammed for more low end torque. And everything else stayed the same. There would be a lot less complaints about the transmission. And I think real world fuel economy would increase.

 

These aren't the Tacoma 2GR curves. That looks like the higher revving Lexus variant. Below is what I figured was the best candidate a while back in the "2016 Tacoma Dyno Torque HP Crve" thread. I kind of gave up looking. This is a "7GR-FKS" from a chinese Prado that has almost the exact same specs as the Tacoma 2GR. This and the 1GR are both at almost exactly 300 Nm at 1500 rpm. (All these charts seem to start at 1200 rpm.)

...and "Atkinson" has zero effect on these curves. (Lexus RC-F has "Atkinson".)

 

[edit]
The 2GR dyno chart I posted above did not come from the linked document below--can't find the source, however I suspect it is the Lexus version of the engine,

I left the link in place as it is an interesting read.
[/edit]

Could be the Lexus version--I got it from this document which does not specify the application. I am of course aware that the "Atkinson" cycle nonsense does not affect these charts; that would be one heck of a torque "suck-out"; but it does effect "real world" performance; and not in a good way based on my limited 3rd Gen driving experience.

Nonetheless the similarity of the torque curves is striking with that same dip and trough between 2000 and 3500 rpm--if that could be tuned out and made to resemble the linear rising slope of the 1GR I suspect drivability would be greatly improved.

I say "if" it can be tuned out as it (the odd torque curve) looks to me characteristic of intake and/or exhaust flow deficiencies. I have seen similar curves on Mustangs with cheap "performance" CAIs that were just pieces of straight pipe and poorly sized rubber elbows, and equally crummy headers--all sorts of rpm and load dependent peaks and valleys.

My feeling is Toyota got carried away with making it "fuel efficient", to the point of forgetting it's supposed to be a truck engine--it will be interesting to see what 2019 or 2020 bring...

 

I have come to believe that statements like these are only made by people that don't understand how simulated "Atkinson" is achieved in this engine. As it relates to "Atkinson", the only difference between the 2GR-FKS and the 1GR is the range of the VVT-i. If the 1GR did not have VVT it would not be as powerful, efficient, or have as high or broad a torque curve. VVT is good. Do you think your 1GR VVT robs you of performance? The problems with this truck's performance is almost entirely related to the DBW throttle control and the A/T shift logic.

The 5VZ closed the intake valves at 42 degrees after bottom dead center (ABDC). The 1GR VVT-i can close them as late as 60 degrees ABDC. The only difference that compels Toyota to call the 2GR VVT-iW simulated / on-demand Atkinson is that it can delay up to 105 degrees ABDC. Mazda SkyActiv does the same thing, they just don't call it Atkinson, AFAIK.

If this negatively effects performance, why would they put Atkinson in the 467 HP Lexus RC-F $60-80k sports car???

 

Fuel economy, to save on "gas-guzzler" taxes, and marketing hype because very few understand what the faux-Atkinson cycle really does--they market it as a performance boosting thing, which it is if we define "performance" as maximum fuel economy.

And yes I do understand how it works--keeping the intake valve open until 105° ABDC, ejecting a portion of the intake air, effectively reducing the engine's displacement and compression ratio; thus reducing the amount of gasoline it consumes and thereby its power output during periods of operation when less power it required--like cruising at steady speeds on level ground.

Here are some "back-of-a-napkin" calculations I made re: the faux-Atkinson cycle operation, based on information provided in this Toyota document and other info I could dig up on the web. I believe what I concluded is a "worst case/maximum possible" effective reduction in displacement, in actual operation I suspect the ECM does not delay intake valve closing to the full extent of the published specs.

If anyone wants to know just about all there is to know about internal combustion engines I recommend John Heywood's

Internal Combustion Engine Fundamentals

Internal Combustion Engine Fundamentals; and/or Charles Fayette Taylor's

$49 The Internal Combustion Engine in Theory and Practice: Vol. 1 - 2nd Edition, Revised: Thermodynamics, Fluid Flow, Performance

The Internal Combustion Engine in Theory and Practice (two volumes). I had the distinct pleasure of studying under Dr. Heywood some many (46) years back...

 

I think a 7-Speed Manual aka 6+1 with a more powerful engine like a diesel would be nice.

 

...and when more power is required the VVT adjusts to provide it, just like any other VVT system. So, where is the problem?

What is the calculated displacement at 60 degrees ABDC using max displacement of 4.0L? Less than 4.0, right? So, 1GR is also atkinson? No one is complaining about that.

 

The 60° ABDC intake closing on the 1GR has nothing to do with the imitation Atkinson cycle and is actually quite a bit less delayed than many "full race" performance cams on plain ol' pushrod V8s that don't close the intake until 80°+ ABDC--and don't idle for shit.

The intake charge has mass and therefore inertia, at higher intake velocities closing the intake valve late provides a "ram" charging effect as the incoming charge's inertia pushes exhaust gases "out of the way" and stacks up against the closing exhaust valve.

The opposite occurs at TDC when the scavenging effect valve overlap allows exhaust gases (which have mass and inertia too) to suck in an amount intake charge in addition to that pulled in by the just downward motion of the piston within the cylinder. Read the references I provided earlier and you will know all this.

This is basic 4-stroke/cycle stuff that existed long before computer controlled (hydraulic or electrical) cam timing--and is quite distinct from deliberately doing it to the extreme (i.e. 105° ABDC when the piston is already more than 1/2 way up into the cylinder) at low loads and engine speeds to eject a portion of the intake charge and reduce the engine's effective displacement.

FYI here is the cam timing for a 1.5 L 1965 Triumph Spitfire that I happened to have on hand (as I used to race them):



Note that the intake closes at 58° ABDC--mechanically and consistently on each cycle as built into the cam profile. Contrary to popular belief not much of this stuff was invented yesterday.

There is nothing radical or "Atkinson" like about the 1GR engine--your making such a statement says more about your knowledge of ICE operation than anything else. Again, read or at least skim through the books I referenced then we can talk further...

 

is not so much the -.5L loss in the 3rd gen but the stupid, idiotic, down right dumb Atkinson cycle engine. who in their right mind wants a engine where the intake valve stays open at the beginning of the compression stroke? there is a video of how the Atkinson cycles works, if that had been playing on a flat screen at the dealership when i bought mine i never would have considered it. only saving grace is the ECT function which i am in 100% of the time, and am fairly certain it disables the Atkinson cycle.

 

You know comparing a racing engine with a 'truck' engine tuned for low end torque (within the constraints of it's shorter than 1GR stroke) is apples to oranges. And you know the dynamics of air flow do not lend themselves to a back of the napkin calculation. E.g. I recall that the displacement of Pruises with similar valve angles are effectively reduced by ~40%. This would put the 2GR at about 2.1L minimum effective (~2x napkin). This is all beside the point, as we agree in principle on this matter.

What I don't understand, and you have not articulated, is why you think this lowest load condition should or does affect performance (efficiency not withstanding). The GM 3.6 competitor has exactly the same max hp/L/rev; so, how has the 2GR been crippled by "Atkinson nonsense"? The only issue I can see is that it may take ~twice as long to phase the cam; but, I can't find anything about how long it takes... never heard any complaints of 1GR cam phase lag. I suspect it is trivial; do you know?

And again... the Lexus RC-F has the most powerful V8 they have ever made and it has 'Atkinson'. You can't honestly think they intentionally crippled this engine (0-60 in 4.4). The only logical explanation is that wider VVT has an imperceptible effect on performance.

Look at page 146 of the pdf you posted... It plainly shows how they numb the throttle control (and is why M/Ts are still apparently affected). IMO, this and the A/T programming are the reason for disappointment. I have seen no credible arguments to suggest otherwise.

 

This is sort of rambling, please bear with my chronic insomnia. Thank you for providing me an opportunity to exercise my brain!

I believe my use of the term "cripple" created some confusion as to my position and understanding of the faux-Atkinson mode. I never meant to imply that this mode caused an overall permanent and fatal crippling of the 2GR engine. However it is inescapable that when activated the "Atkinson" mode diminishes engine output. This is of course what it is intended to do; reduce fuel consumption when only minimal HP is needed (it takes only 30 to 35 HP to hold a 4000 lb vehicle at 60 mph on level ground).

Cripple was no doubt too strong a term as it implies a permanence; "Temporarily alters" (negatively) would be better. That it is a temporary mode employed only when the ECM determines it to be in your best interest is good; making it optional with end user ability to disable it would be even better.

When the "Atkinson" mode it is not enabled the engine behaves as I would expect any contemporary dual VVT 3.5 L engine to behave; and as is common with engine "downsizing" the "needed" and much publicized HP increase over the 4.0 engine is achieved by sacrificing low-end torque in favour of maintaining a more extended ("flatter") curve after the torque peak, thus moving the HP peak from the 1GR's 236 @ 5200 rpm (238 lb·ft) to 278 @ 6000 rpm (243 lb·ft). Impressive and testament to the new engine's design and tuning is that peak torque for the 14% lower displacement 2GR is just 1 lb·ft less (265 lb·ft @ 4600 rpm) than the 1GR's 266 lb·ft @ 4000 rpm--it is unfortunate, for a truck engine, that low-end torque had to suffer.

While this may be the future of truck engines it surely does not reflect the traditional emphasis on low-end torque, the (rightful) holy grail of diesel enthusiasts.

This is of course entirely independent of the "Atkinson" mode. Valve timing and better intake/exhaust flow are all that's necessary to shift the powerband. On engines with less sophisticated control systems exhaust header design alone can narrow/widen/move output torque over a surprisingly wide range.

That the ECT power mode exists is to me an indication that Toyota was well aware of the challenges presented by the new engine and transmission. Allowing it to rev higher into the "meat" of it's powerband does improve driveability. I drove my neighbor's 2017 to Daytona t'other day and played with both the ECT and "S" modes. The "slapstick" mode is fun but completely removes the primary reason for having an automatic transmission. It is just one pedal away from have a 6-speed manual.

Including an "Atkinson" mode on the Lexus is more likely related to marketing hype¹ and EPA emission and fuel economy requirements, than "performance" (in the traditional sense of implying "high performance", increased power). Turn it off and you have a plain ol' gas-guzzling V8 like the unapologetic 526 HP 5.2 L Voodoo engine in the latest Mustang GT350.

People that buy expensive sports cars, or sort of expensive sports cars², or even the more popular SUVs and pickups don't really give a crap about fuel economy--heck, I don't really give a crap about it³ and haven't bought a car based upon it in well over 30 years. The government keeps telling us that "Americans want smaller fuel efficient vehicles."--the reality however is that the US auto industry (domestic and imports) is surviving mostly on big-ass SUVs and pickups.

To my mind Toyota's decision to switch the Tacoma to a smaller displacement higher revving engine was a marketing blunder, I'm sure it was driven by government imposed emission and fuel economy requirements. It is certainly not on the same scale as New Coke, but a blunder (perhaps unavoidable) nonetheless. A local Ford dealer has four low mileage (1.5 to 20k miles) 2016/17 Tacomas on their used lot, the Toyota dealer has three.

All else being equal there is "no replacement for displacement". It will be interesting to see what Toyota does with the 2019 or 2020 Tacoma--or maybe even the 2018 MY which seems to now be scheduled for early 2018 release...

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¹ - I am amazed by how many, including my "I thought" mechanically inclined neighbor (he has a very nice 427 AC Cobra replica), believe the "Atkinson" mode produces more power--this in no small part due to the vague references and descriptions utilized in hyping same and implying that the Atkinson cycle mode is a full time thing--as in:

"Tacoma’s available 3.5-liter DOHC V6 direct-injection Atkinson-cycle engine gives you more of everything you want. It’s got 278 hp and 265 lb.-ft. of torque, giving you the muscle you need to tow, haul and run the dunes. It’s also more efficient, giving you better mpg too."
from the 2017 eBrochure

² - $60k to $80k in 2017 for a high performance sports car is not a whole lot. My '98 SL500 was $101,275 when new, and even then that was not "a lot" as in Ferrari/Lamborghini/Maserati/etc.

³ - I spent 5 years commuting 110 miles round trip in a 2003 Mustang GT, 18-19 mpg on average--it wasn't cheap to run but it beat the crap out of having to commute 110 miles a day in an Echo.

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As a complete aside, but relevant to pushing up claimed HP by spinning a small engine faster:

The 1st generation Honda S2000 was advertised as producing 240 HP (n/a) from 2.0 L; a very impressive 120 HP/L super-bike territory output (imagine 420 HP from the 2GR). It did make 240 HP but it happened @ 8600 rpm. At 2500 rpm it barely managed 50 HP and the car was an absolute dog "off the line while on the street" unless as one magazine editor put it "...you drive it like you just stole it." It didn't make 100 HP until 4500 rpm and to get any sort of impressive street performance without bogging you had to launch it at 3500 to 4000 rpm, which made onlookers think you were some sort of "gee look at me" attention grabbing idiot.

In 2004 with the 2nd Gen S2000 Honda quietly bumped the engine to 2.2 L, pumped up the low-end torque and moved the 240 HP peak to a still high but more reasonable 7600 rpm. The car became much more drivable but it was never the "Miata killer" Honda wanted and was dropped in 2009. It was only produced with a 6-speed manual transmission, that engine with a slushbox would have been a god-awful mess.