Highway speed gear 3.07 vs 2.87

[Ronmar]

Yea, what inefficiencies?

 

[Awesomeness]

The automatic is not significantly more inefficient when the TC is locked. Why do you suppose the ENTIRE automotive industry has adopted automatics for better fuel economy and control? Also it's a 5 speed up to their test speed not a 4 speed, and if you surpass 65 mph you can easily get into 7th gear making it a 6 speed. My 3700SP works great along side the ECO hubs. I daily drive my truck, do all my own work, and if it sucked at any aspect of how it operates you can bet I would switch back in an instant - it wouldn't cost me a dime. So what exactly is my motivation to continue to defend my position here? If you think a couple of $400 ECM flashes is the reason you are sadly mistaken - I don't own a performance shop with a chassis dyno to make $400 once every couple months when someone decides they need their speedo to read correctly. I have a $40,000 saltwater aquarium in my lobby - this service ain't even paying for fish food pal.

You're confusing me with someone else. I haven't said anything about you selling anything. But you're doing an awful lot of chest thumping, to help prove your points, I guess.

The study even says it in passing, because, like me, I assumed everyone was on the same page about transmissions. "Automated manual transmissions provide the same user interface as an automatic transmission, i.e. accelerator and brake pedal, with the efficiency benefits of a manual transmission." Manual transmissions have fewer moving parts, no/less pumps, just the one clutch, ... basically less of everything. And that means efficiency is improved, pretty simple. Go look up fuel mileage on any car you can buy with a manual or automatic (e.g. Jeep), and see which one is better.

As to why the entire auto industry uses automatics, the same reason all cars come with backup cameras, power windows, etc. People are lazy, and the manufacturers are running out of meaningful drivability (e.g. engine, suspension, reliability, etc.) features to put in, so it's lots of convenience-fluff now.

 

[GeneralDisorder]

Sorry - others have claimed I'm trying to pump up sales because the designer of the ECO Hubs is appreciative of my review and programming his ECM so he is including my information with every sale in case people need my assistance with correcting their speedo or increasing their performance, etc. Not the case since I could care less one way or the other given the small amounts of money involved. Just helping the community in that regard.

The difference in manual vs. auto efficiency is negligible. It's not just that people are lazy - it's that automatic's have caught up and surpassed manuals in terms of performance and economy. And when you consider the need to eventually replace the dry dual-clutch (AMT's use twin clutches to shift between twin input shafts typically) when it wears out they typically have increased cost of ownership compared to automatics. Check out the complete cluster-F that is the Ford Powershift. The technology hasn't really taken off compared to true automatics and CVT's.

I think ultimately eliminating the entire drivetrain in favor of electric third members is probably the future. Hopefully someday I can yank the entire drivetrain and install batteries in it's place to power these:

https://www.meritor.com/technology/

 

[Awesomeness]

The difference in manual vs. auto efficiency is negligible. It's not just that people are lazy - it's that automatic's have caught up and surpassed manuals in terms of performance and economy. And when you consider the need to eventually replace the dry dual-clutch (AMT's use twin clutches to shift between twin input shafts typically) when it wears out they typically have increased cost of ownership compared to automatics. Check out the complete cluster-F that is the Ford Powershift. The technology hasn't really taken off compared to true automatics and CVT's.

I think ultimately eliminating the entire drivetrain in favor of electric third members is probably the future. Hopefully someday I can yank the entire drivetrain and install batteries in it's place to power these:

https://www.meritor.com/technology/

It's hard to argue that the automatic's inefficiency is insignificant, while also arguing that the hub heat is very significant. The automatic transmission generates way more heat than the hubs (or a manual transmission), so much that it has its own cooling system. Do AMTs have cooling systems? I googled it, but couldn't find anything.

The increased number of gears in new automatics are a huge boost the MPG efficiency, and now some automatics are starting to get better MPG than manuals because they have a few more gears (8-speed auto vs 6-speed manual). The CVTs are theoretically even better, if not for the complexity and reliability issues. It took decades for the automatics to reach an engineering maturity that made them mainstream, then a few more decades to start "taking over". I'm not sure if we'll get there with CVTs, despite the faster technological advances, before electric drives stop efforts to improve them.

Electric drivetrains change all of it. Since electric motors develop maximum torque as they approach stall (0 RPM), they set themselves up pretty naturally for vehicles. You don't have to get it spinning, then engage a clutch, like an ICE. Match the motor characteristics to the tire/wheel/axle/etc., and you get tons of pulling/launch power, with a minimum motor package. The problem is that on electric motors low-end torque is amperage-limited, and then at some RPM they become voltage limited instead, so they have to be very carefully engineered for their purpose. It looks like Meritor's got around that with a gearbox... "Two-speed gearing allows for a smaller, lighter-weight motor and heavier load capacity, operating in the sweet spot for maximum efficiency."

 

[Lostchain]

So at 2600RPM the engine might need 10gal/hr of fuel to make 100HP, and at 1200RPM it needs 9.5gal/hr. That's a 5% change, not a 50% change, like you suggested.

Back to this point for a moment. Your own data on the 3116 shows a 50% increase in Fuel consumption between 1200RPM and 2600RPM at full load (dyno test). Now you also say at some lower load, that consumption delta drops all the way down to 5%. That didn't make any sense to me but I figured that is easy to test.

So my first test was to check my fuel flow at 1200RPM in neutral and then compare it to my fuel flow at 2400RPM in neutral. My results are in the video linked below, but the summary is 1.3gph at 1200, 4.0 at 2400. That is quite a bit more in-line with your CAT Dyno data. Well above 5%

IMG_1916.MOV - Google Drive
Note: in these videos, RPM is upper left, Fuel Flow in GPH is Lower Left.

So then I thought I'd try to test your idea with a road test. My understanding of your position, is that it takes X fuel to do a given speed in the LMTV and if the only variable is the RPM, then again, there will not be a dramatic difference, even 5% is suspect.

I apologize in advance for the videos of my test, it is tough to film and keep your eyes on the road and your speedo at the same time. Basically I tried to hold the engine as close to 42 as possible, as that was basically at redline in 3rd gear for the high-rpm test. The videos linked below show the full test, it took me roughly 40 seconds on both tests to get the speed (and fuel flow) stabilized, and they were both taken at the same start and end points.

This is the low RPM video, and you can see that most of the time it is between 4-6 gph

IMG_1915.MOV - Google Drive

This is the high rpm video and you can see that most of the time it is between 7-8 gph also, the boost is significantly higher on the high RPM test and my temperature was rising rapidly. This is basically how my truck ran before the ECO hubs, mega boost and fan kicking on every 2 minutes to maintain highway speeds.

IMG_1917.MOV - Google Drive

Again, my testing showed a much greater than 5% difference in fuel consumption when the only variable was engine RPM. I am curious what I am missing here with my tests.

 

[johnz]

There are people that never admit they are wrong and don't have the ability to apologize.

We all know people who just can’t apologize — well, here’s why

Non-apologizers are maddening to be around, especially when they’re clearly in the wrong. Here’s what drives their unrepentant ways and what you can do, from psychologist Guy Winch.

ideas.ted.com

Spot on! That's exactly what's at work here.. Once I identify this type of behavior, any hopes for a productive discussion ceases and I simply enjoy it for what it is; entertainment... Thanks for posting the link!

 

[GeneralDisorder]

Back to this point for a moment. Your own data on the 3116 shows a 50% increase in Fuel consumption between 1200RPM and 2600RPM at full load (dyno test). Now you also say at some lower load, that consumption delta drops all the way down to 5%. That didn't make any sense to me but I figured that is easy to test.

So my first test was to check my fuel flow at 1200RPM in neutral and then compare it to my fuel flow at 2400RPM in neutral. My results are in the video linked below, but the summary is 1.3gph at 1200, 4.0 at 2400. That is quite a bit more in-line with your CAT Dyno data. Well above 5%

IMG_1916.MOV - Google Drive
Note: in these videos, RPM is upper left, Fuel Flow in GPH is Lower Left.

So then I thought I'd try to test your idea with a road test. My understanding of your position, is that it takes X fuel to do a given speed in the LMTV and if the only variable is the RPM, then again, there will not be a dramatic difference, even 5% is suspect.

I apologize in advance for the videos of my test, it is tough to film and keep your eyes on the road and your speedo at the same time. Basically I tried to hold the engine as close to 42 as possible, as that was basically at redline in 3rd gear for the high-rpm test. The videos linked below show the full test, it took me roughly 40 seconds on both tests to get the speed (and fuel flow) stabilized, and they were both taken at the same start and end points.

This is the low RPM video, and you can see that most of the time it is between 4-6 gph

IMG_1915.MOV - Google Drive

This is the high rpm video and you can see that most of the time it is between 7-8 gph also, the boost is significantly higher on the high RPM test and my temperature was rising rapidly. This is basically how my truck ran before the ECO hubs, mega boost and fan kicking on every 2 minutes to maintain highway speeds.

IMG_1917.MOV - Google Drive

Again, my testing showed a much greater than 5% difference in fuel consumption when the only variable was engine RPM. I am curious what I am missing here with my tests.

Kinda what I figured we would see. There's a small factory's worth of machinery being flung around at high speed in our drivetrain. Running all that stuff at double the speed is going to require fuel.

The study that showed 22% improvement stated it was mostly due to final drive ratio and although it's not stated anywhere specifically that I can find, I have to assume when they changed the FDR to 4.50 that was retaining the 2:1 reduction hubs - there was no mention of removing them so I have to assume they remained in place and they used a 2.25 R&P third member.

Those reduction hubs probably account for some of the additional economy we are seeing - partially that and partially that we took the FDR higher than the study did. Those hubs generate a lot of heat and noise - you can HEAR the lash in them. Heat and noise require power to create and that's lost energy.

I daily drive my truck and what I'm seeing currently is that before the change I was having to fill up every other Friday and after the change it's about 2.5 weeks before I'm getting down to where I was before. It's more mixed driving than straight cruising at steady speed. I would estimate I'm seeing about 15-20% improvement in mixed driving.

 

[Awesomeness]

Back to this point for a moment. Your own data on the 3116 shows a 50% increase in Fuel consumption between 1200RPM and 2600RPM at full load (dyno test). Now you also say at some lower load, that consumption delta drops all the way down to 5%. That didn't make any sense to me but I figured that is easy to test.

So my first test was to check my fuel flow at 1200RPM in neutral and then compare it to my fuel flow at 2400RPM in neutral. My results are in the video linked below, but the summary is 1.3gph at 1200, 4.0 at 2400. That is quite a bit more in-line with your CAT Dyno data. Well above 5%

IMG_1916.MOV - Google Drive
Note: in these videos, RPM is upper left, Fuel Flow in GPH is Lower Left.

So then I thought I'd try to test your idea with a road test. My understanding of your position, is that it takes X fuel to do a given speed in the LMTV and if the only variable is the RPM, then again, there will not be a dramatic difference, even 5% is suspect.

I apologize in advance for the videos of my test, it is tough to film and keep your eyes on the road and your speedo at the same time. Basically I tried to hold the engine as close to 42 as possible, as that was basically at redline in 3rd gear for the high-rpm test. The videos linked below show the full test, it took me roughly 40 seconds on both tests to get the speed (and fuel flow) stabilized, and they were both taken at the same start and end points.

This is the low RPM video, and you can see that most of the time it is between 4-6 gph

IMG_1915.MOV - Google Drive

This is the high rpm video and you can see that most of the time it is between 7-8 gph also, the boost is significantly higher on the high RPM test and my temperature was rising rapidly. This is basically how my truck ran before the ECO hubs, mega boost and fan kicking on every 2 minutes to maintain highway speeds.

IMG_1917.MOV - Google Drive

Again, my testing showed a much greater than 5% difference in fuel consumption when the only variable was engine RPM. I am curious what I am missing here with my tests.

Thanks for doing the test. And yes, that is my position that you should not see a huge difference between the two.

I went through the second video, and took the average of the "Estimated Fuel Rate gal/h" reading at the beginning of the each second (as best I could do, pausing/playing), 0:34-1:22, and it's 5.14 gal/hr. At 43.5MPH, that would be 8.46MPG.

I did the same for the third video, 0:20-1:22, and it's 8.32 gal/hr. At 42MPH, that's 5.05MPG.

That's a 41.3% reduction, which is a highly unexpected finding. It doesn't line up with anything (e.g. my theory that it should be as flat as the torque curve, your theory that it should cut in half like the two RPMs on the fuel consumption chart, the theory that removing the hubs is required to get improvements, or any of the engineering studies about possible fuel consumption improvements).

So I'm a bit stumped, for now. A couple thoughts...

• This test likely represents the "worst case", with the largest possible spread between results. It would be hard to drive like this for long durations, so the 60 seconds may not be representative of a whole tank of fuel, or longer-term.
• How is the fuel rate "Estimated", and what is it's accuracy? Anecdotally, I know that my daily vehicles claim ~20% MPG than I get by tracking actual fuel usage, even over long durations (>100k miles). Are any inaccuracies similarly proportioned over the whole range (e.g. 10% off at 50% throttle, and 20% off at 100%)?
• In the low RPM test, "Throttle Position" holds pretty well around 40, and in the high RPM test, it's around 100.
• I have never been able to find the torque curve for these specific military 3116's, but the spec sheet lists 9 other 3116's, and they don't seem to have a "hard dive" in efficiency at the top end (2500-2800RPM). I don't think I have a torque curve for a C7 (I'll need to look).
• The 5-8.5MPG is similar to my 3116's mileage, which has averaged 4.5-7MPG (5.4MPG lifetime), with a couple "best tanks" up in the mid-7's. My MPG also didn't change much when I swapped to 3.07:1 gears (it went from 5.2MPG before the swap, to 5.4MPG after... 4% improvement).

 

[ramdough]

Maybe it would be good for those on here with differing beliefs to work together to come up with a reasonably repeatable range of easy tests to determine what an actual difference is made under various specific load conditions.


Sent from my iPhone using Tapatalk

 

[Lostchain]

That's a 41.3% reduction, which is a highly unexpected finding. It doesn't line up with anything (e.g. my theory that it should be as flat as the torque curve, your theory that it should cut in half like the two RPMs on the fuel consumption chart, the theory that removing the hubs is required to get improvements, or any of the engineering studies about possible fuel consumption improvements).

Appreciate you taking the time to look at my videos and coming up with the numbers.

To be clear, I never thought that the fuel consumption would be cut in half, what I said was:
"A 50% reduction in rpm manifests less than 5% better MPG in your mind?"

What I was trying to convey with that question is that, to me, an RPM drop of 50% is a huge reduction, and should manifest in a substantial (far greater than 5) percent drop in fuel usage. I was surprised you thought 5% was the upper limit to a change of that magnitude.

You said that you averaged it out to a 41.3% reduction on my test videos, and I am not surprised by that in any way. Do I think it is going to be 40% better all the time? Absolutely not there are far too many variables to make that leap. But wat I AM saying, and what I currently believe my tests have proven, Is that RPM has a large influence on the efficiency of our trucks, and thus the ECO hubs make a large difference. I don't actually care that much about the fuel efficiency of our vehicles myself. I bought the ECO hubs because I found I was avoiding taking my truck out on long trips because even at 50MPH the engine was screaming and the fan was running constantly. It pained me to flog my truck so hard, yet people lined up behind me and rushed to pass me for driving so slow. For the record I have absolutely no tie to the dude who make the ECO hubs. I'm just a happy customer who enjoys driving his truck a whole lot more now.