Hot Weather Performance

[D Fresh]

If you had done things in a scientific way where you could legitimately attribute the changes to locking out the gear sure I would concede that point but from an engineering and mathematical standpoint based on facts and quantifiable data you are barking up the wrong tree, it is simple lower gear means higher revs which means more fuel consumption if we are both going 70 and you are in 9th gear and i am in 10th all other factors constant I am gonna use less fuel because less rpm means fewer combustion cycles hence lower fuel use If you are constantly accelerating (using the physics definition not the normal ppl one) yes you will use more fuel because acceleration requires energy so constantly braking speeding up weaving in and out will all use more gas because you need more energy to maintain your speed due to your velocity changes that isn't cause of the transmission its cause of your driving style

I tested my theory last fall as scientifically as I could. While I don't lock out gears, I use tow mode, I believe the results would be similar.

What you are forgetting in your theorization is load. Efficiency depends on load just as much as rpm and speed.

My testing was done on 3 consecutive tanks with the same drives and driver.

17k miles

Lifted on E-Rated 33"s. Otherwise stock.

Hand calculated mileage accross entire tanks. All filled at the same pump, stopped at first click off. All tanks were Colorado premium, 91 octane.

Tank driven in D= 16.15 mpg

Tank driven in Tow= 17.69 mpg

Tank driven in S= 15.56 mpg

The factory shift logic in D is quite horrible if you actually drive your vehicle. It is much more efficient to lightly roll onto the throttle when you need to accelerate. If the vehicle is in the proper gear you can do so. With the factory shift logic in D that is impossible. Since the truck wants to lug around at 1300 rpm, well outside of the power band, anytime a slight bit of acceleration is needed or load is increased you're dumping fuel in. Hit a hill at 1300 rpm in any gear and the load is going to sink you. You'll need to mash the skinny pedal to maintain speed, forcing multiple downshifts and much higher rpm, while under more load. Same thing when the speed limit jumps 10 mph, try to accelerate and you're going to initiate a downshift.

I'm talking from a driveability AND MPG standpoint here. I'm not even going to get into the fact that driving around in 8th gear at 1200 rpm and 45mph is not good on an engine.

The ten speed isn't overkill IMHO, as others think. But it's shift logic in D as delivered by Ford is borderline retarded when paired with a small displacement boosted engine.

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[dtech]

I tested my theory last fall as scientifically as I could. While I don't lock out gears, I use tow mode, I believe the results would be similar.

What you are forgetting in your theorization is load. Efficiency depends on load just as much as rpm and speed.

My testing was done on 3 consecutive tanks with the same drives and driver.



The factory shift logic in D is quite horrible if you actually drive your vehicle. It is much more efficient to lightly roll onto the throttle when you need to accelerate. If the vehicle is in the proper gear you can do so. With the factory shift logic in D that is impossible. Since the truck wants to lug around at 1300 rpm, well outside of the power band, anytime a slight bit of acceleration is needed or load is increased you're dumping fuel in. Hit a hill at 1300 rpm in any gear and the load is going to sink you. You'll need to mash the skinny pedal to maintain speed, forcing multiple downshifts and much higher rpm, while under more load. Same thing when the speed limit jumps 10 mph, try to accelerate and you're going to initiate a downshift.

I'm talking from a driveability AND MPG standpoint here. I'm not even going to get into the fact that driving around in 8th gear at 1200 rpm and 45mph is not good on an engine.

The ten speed isn't overkill IMHO, as others think. But it's shift logic in D as delivered by Ford is borderline retarded when paired with a small displacement boosted engine.

Just this summer I've begun using tow mode when going up hills - as I've experience lugging , which I believe would negatively impact fuel economy and not ideal for the engine. . This started occurring on warmer days with very dry air, this past week with cooler temps and higher humidity the lugging isn't noticeable. I've also relocated to a more hilly area than Denver , elevation around 7,500 in the past year, living in Denver prior to the that never noticed much lugging . Of course if I use more gas pedal the tranny will downshift but have to agree regards your opinion on shift logic - esp when it pertains to hills. I use tow mode going uphill only, turning it off on flat and downhill - we'll see how robust the tow mode button holds up over time.

 

[D Fresh]

Just this summer I've begun using tow mode when going up hills - as I've experience lugging , which I believe would negatively impact fuel economy and not ideal for the engine. . This started occurring on warmer days with very dry air, this past week with cooler temps and higher humidity the lugging isn't noticeable. I've also relocated to a more hilly area than Denver , elevation around 7,500 in the past year, living in Denver prior to the that never noticed much lugging . Of course if I use more gas pedal the tranny will downshift but have to agree regards your opinion on shift logic - esp when it pertains to hills. I use tow mode going uphill only, turning it off on flat and downhill - we'll see how robust the tow mode button holds up over time.

I think that for my mixed driving and style I'd do best to take it out of tow mode when I get up above say 50 mph except for hilly terrain. But it's too much of a pain to do so, so I set it and forget it.

I wish the button was on the shifter. Then I'd use tow under 50mph, and turn it off unless needed above. I suspect this is one reason @OFC Ranger prefers to lock gears out. Easier to reach.

 

[JasonTremor]

Did a few stop and go short trips today in upper 90's temps and then did my usual sport mode to enter the interstate on ramp. It fell on it's nose compared to 70 degree ambient temp days. Guess I'll datalog it sometime with the SCT logger software and see how bad the heat soak is.

 

[dtech]

I think that for my mixed driving and style I'd do best to take it out of tow mode when I get up above say 50 mph except for hilly terrain. But it's too much of a pain to do so, so I set it and forget it.

I wish the button was on the shifter. Then I'd use tow under 50mph, and turn it off unless needed above. I suspect this is one reason @OFC Ranger prefers to lock gears out. Easier to reach.

Off topic but I'm amused at all the "new" hockey fans in Denver - a good many I'd wager don't even understand the game. I had a blast yrs back taking the broken down bus from Zang's across I-25 to watch what IIRC were the Rockies play at Mcnichols and even front row seats were cheap.

 

[D Fresh]

Off topic but I'm amused at all the "new" hockey fans in Denver - a good many I'd wager don't even understand the game. I had a blast yrs back taking the broken down bus from Zang's across I-25 to watch what IIRC were the Rockies play at Mcnichols and even front row seats were cheap.

Denver has always been full of fake fans. Manning had to quiet the crowd when his offense took the field at Mile High. The fools didn't know you were supposed to be loud when your team plays D and quiet on offense.

 

[Ninda]

Yeah that will be a change! It's hot here!

Yeah that will be a change! It's hot here!

Yes, we were there last week looking at houses around Mount Airy, wasn't bad in the mornings. the afternoons that's another story.

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