6.4 Road Trip Results

[tjfdesmo]

Just completed a trip to Coleman, OK and back, 2687 miles, Max MPG 15.9, Min MPG 14.5, Trip AVG 15.1, EVIC Indicated Trip Avg 18.0. They don't call it the Lie-O-Meter for nothing LOL. This was empty, running 75. Pretty flat terrain along the I-10, I-20 corridor, and remarkably little wind. I was hoping she'd get 16 on a trip like that, but at 7K+ lbs with a gas motor, it is what it is.

 

[Firebird]

That's really not that bad. How many miles on the truck? What gears?

 

[tjfdesmo]

That's really not that bad. How many miles on the truck? What gears?

24K miles and 4.10 gears.

 

[SouthTexan]

Yeah, they don't call a lie-o-meter for nothing. To be fair though every vehicle I have had from my Ford's to BMW's or my wife's vehicles like her Mercedes' to Infiniti's have all been off by 1-3 mpg.

 

[tjfdesmo]

Yeah, they don't call a lie-o-meter for nothing. To be fair though every vehicle I have had from my Ford's to BMW's or my wife's vehicles like her Mercedes' to Infiniti's have all been off by 1-3 mpg.

Yeah, this is about the least accurate one I have had with a gas motor. My '05 CTD was really wacky, the harder I worked it the more inaccurate it got. If I was pulling heavy it was sometimes 6+ mpg off. That was a real head-shaker. With a toy hauler on the horizon, I wish I had the old girl back.

 

[JohnnyMac]

but at 7K+ lbs with a gas motor, it is what it is.

This^^^

 

[GsRAM]

Not bad considering the speeds you were running. When it comes to mpg, speed kills. Plus you have the 4.10s. I've been up over 17mpg average on a mostly highway trip, empty with my 73s, but I try to keep her around 70.

 

[Nick@GotExhaust]

O man I dont even want to think about hand calculating my Power Wagon then. My Lie-O-Meter says 12.5 and 11.xx in the winter. its not all the trucks fault, I like to hear that Solo Performance muffler delete scream bald eagles out the tail pipe!

 

[mohemipar]

If I reset mine and drive the truck just to work and back M – F it will tell me I’m averaging around 8 MPG by Friday. If 8 MPG is the truck lying to me I’ll take the sugar coating. Lol.

 

[tjfdesmo]

Not bad considering the speeds you were running. When it comes to mpg, speed kills. Plus you have the 4.10s. I've been up over 17mpg average on a mostly highway trip, empty with my 73s, but I try to keep her around 70.

Agree 100% on speed. But here's the deal with gearing, with 4.10s I am at 2K RPM at 75 MPH(Peak torque is 4K RPM), and it will barely pull even slightly rolling terrain in 6th gear without downshifting, and this is at lower elevations. There were plenty of those times on this trip where the couple hundred fewer RPMs with 3.73s would have caused it to unlock the converter and downshift, etc. When that happens repeatedly MPG really suffers. We already did a trip last year into Colorado, and at higher elevations it really struggles even with 4.10s.

 

[Sweetee]

Just for comparison, I drive for our local dealership doing dealer trades. Last Tuesday I brought a 5500 RC 6.4 back from Michigan (about 400 miles). It was an unfinished cab-chassis(no weight - just the frame out back) and I got 13.9 mpg. Of course, this one had a 4.88 rear gear. It was one bouncy ride!

 

[sandawilliams]

Agree 100% on speed. But here's the deal with gearing, with 4.10s I am at 2K RPM at 75 MPH(Peak torque is 4K RPM), and it will barely pull even slightly rolling terrain in 6th gear without downshifting, and this is at lower elevations. There were plenty of those times on this trip where the couple hundred fewer RPMs with 3.73s would have caused it to unlock the converter and downshift, etc. When that happens repeatedly MPG really suffers. We already did a trip last year into Colorado, and at higher elevations it really struggles even with 4.10s.

I do a lot of towing in Colorado mountains. About 8500# with another 1200 in the bed. My 3.73's do great. Not saying that 4.10's wouldn't be a little better.

 

[tjfdesmo]

Just for comparison, I drive for our local dealership doing dealer trades. Last Tuesday I brought a 5500 RC 6.4 back from Michigan (about 400 miles). It was an unfinished cab-chassis(no weight - just the frame out back) and I got 13.9 mpg. Of course, this one had a 4.88 rear gear. It was one bouncy ride!

How does the Aisin trans behave behind the 6.4?

 

[Sweetee]

How does the Aisin trans behave behind the 6.4?

This is the first time I've driven a 6.4 with the Aisin, but over 370 miles, it was flawless. I actually got better mileage (by 2 mpg) with the 6.4 4x2 than I did with the 6.7 4x4. Of course, that was "naked" and not towing!

 

[tjfdesmo]

This is the first time I've driven a 6.4 with the Aisin, but over 370 miles, it was flawless. I actually got better mileage (by 2 mpg) with the 6.4 4x2 than I did with the 6.7 4x4. Of course, that was "naked" and not towing!

I would have gladly paid to get the Aisin if they offered it in the pickups, but only the C&Cs can get it.

 

[SouthTexan]

Doesn't the Aisin 66 have the same ratios as the Aisin 69? If so, the it will have taller gearing(less torque multiplication) than the 66RFE is some of the higher gears.

 

[tjfdesmo]

Doesn't the Aisin 66 have the same ratios as the Aisin 69? If so, the it will have taller gearing(less torque multiplication) than the 66RFE is some of the higher gears.

You got me there, ST, I don't know. Based on what I have read on TDR about the "behavior" of the Aisin, I was more thinking about it not having adaptive learning, and perhaps being more predictable, as that's how I like stuff to work. The more computer nannyism, the less I like something. I'll have to try to dig up a chart out of curiosity. This thing can't tow much in 6th anyway, so if the Aisin has a useable fifth gear for pulling, that could be a plus???

 

[carmantl]

The only issue I have with my Aisin behind 6.4 in my 2017 chassis cab is that shift points are limited to 4600 RPM so I don't get to use the upper 1000 RPM. I am guessing this is why my engine is de-rated to 370 HP since I don't get to use the upper 18% or so of my power band. I have a 9 foot Knapheide utility bed on it. Truck weighs 7375 empty, GVWR is 11000, current loaded weight is around 10200. I have yet to see mileage above 10 hand calculated. Liemeter says 11.

 

[tjfdesmo]

The only issue I have with my Aisin behind 6.4 in my 2017 chassis cab is that shift points are limited to 4600 RPM so I don't get to use the upper 1000 RPM. I am guessing this is why my engine is de-rated to 370 HP since I don't get to use the upper 18% or so of my power band. I have a 9 foot Knapheide utility bed on it. Truck weighs 7375 empty, GVWR is 11000, current loaded weight is around 10200. I have yet to see mileage above 10 hand calculated. Liemeter says 11.

Thanks for the feedback carmantl, I assume the derate is for duty cycle reasons, same as the Cummins in the C&C???

 

[6.4 dude]

Here you go, got one of each.