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6.4 Rocky mountain towing review

406Linetrash

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Thought I would post another towing review for the 6.4. Seems to be a popular subject with varying numbers. This one should different only in the fact this should be a worst case scenario review. Not a stock truck. At higher speeds in the mountains. I crossed the continental divide multiple times. As well as took a few sections that your grandpa used to take to school. The ones that are somehow uphill both ways. Multiple uphill runs from 4500-6500 feet.

Ran from montana to salt lake south on i15. With a detour through hwy 30 to lava hot springs. I'll start and end the review in helena montana. It's central and my first fill up since I left with a partial tank and screwed around on the first one running errands.

Truck: 2020 2500 QCSB 4x4. 4.10/LSD. Leveled. 35x11.5r18 AT's. Front air dam trimmed to 2wd drive style. Timbren SES

Trailer: 29.5 ft (33 actual) jayco eagle fifth wheel. Dry weight of about 10k pounds. GCW at cat scale was 17430 for this trip. B&w is all the way down and forward. Have 7" of bed rail clearance and trailer is level behind the truck.

I've pulled this trailer with a 2019 L5P duramax before. As well as had multiple 6.7 cummins, 5.9 cummins and a 6.7 ford. If you want comparisons. Only gasser I can compare is a 6.0 chevy. That deserved to be burned down it was so gutless.

The TLDR. First gas truck in like 15 years. Overall MPG for the trip was 8.5 mpg. Plenty of power. Ran better than I expected. Transmission is great. Shifts great. Ran cool. Small tank is an issue when pulling. Speed is your mileage killer. You can do 10mpg. But you better not break 65. Or it better be flat. 4.10's are absolulty the way to go in these trucks. Unless you don't pull at all. Don't regret the gasser at all. Fits all my other needs better. Now that these 1k mile runs are a once or twice a year trip I'm more than happy with performance. If I was still dragging this kind of weight across multiple states. Multiple times a year. I would go diesel. But we stay in the montana area for 90% of our camping. Ran 89 and 91 octane the whole trip depending on what was available.

Helena to butte: 70-75mph. I fought the hell out of a headwind. Like 40mph in my face. This is 60miles of up and down. Long grades. 5.5 mpg. ( To be fair I've had multiple runs in my L5P at 8.5 mpg on this stretch)

Butte to dubois idaho. 70-75mph. Straight into the wind. Another 5.5 mpg tank. I went 130miles and my fuel light was on. Slowing down would absolulty have helped. (not uncommon to do 10mpg in my L5P on this stretch)

Dubois to the tremonton area. 70-75 mph. Got 8.5 mpg on this stretch. Little flatter and wind died down.

tremontonn area to outside salt lake. 70-75 at first. Then traffic and construction slowed us to 55-65 depending on conditions. This tank yielded 10.8. (You'll see a trend here.)

Vacation stuff in/around salt lake unloaded. Tank was 11.5 mixed city/hwy.

Salt lake to mcannon. 70-75mph. Detour to hot springs was 65mph. Overall tank was 9. Around 8 during the 70-75 section. Lie o meter ran above ten during the 65 sections.

Mcannon to dubois. 65. 10 mpg tank. Filled up in dubois cause I was doubting making it to butte if I didn't.

Dubois to butte was 8. Filled up in butte in case 5.5 mpg on previous run wasn't a fluke. Turns out I could have skipped this fill up.

Butte to helena 70-80mph. 8 mpg tank.

These are rough numbers. Hand calculated mileage for whole trip was 8.2.

Power was fine. Trans spent most of it's time in 6. Some In seventh. Some in 5th. A few grades pulled in 4th about 4800 rpms. I was able to gain speed on grades and pass semis if needed. Cruised along great.

Temps were rock solid. Outside was 45-75 degrees. Hottest temps were 175 trans. 218 coolant. 230 oil. All these dropped quick. Cooling seems more than up to the job. I pulled over once and the grill shutters were closed.

The truck will drag this weight around 70-80 with ease. Climb steep grades at 65 no problem. But you will pay for it at the pump. If you slow down a little. Or live in flat terrain. I see no issues getting 10 plus out of this. To be fair to truck. I would disregard first two tanks. Heading into a wind that strong isn't a fair comparison.

I could see the small tank being an issue in states that are less populated. I knew where there was fuel. But in unknown territory, hitting wind or just moving to fast. This could catch a guy. These trucks need a bigger tank. I filled up twice at half tank cause I was unsure what was ahead.

Overall I'm happy with the pull. I don't regret jettisoning the diesel at all. This is a better fit for my other needs. And am willing to sacrifice the mileage in a once a year long haul.

Overall. This should give you an idea of worst case scenario pulls and mileage if your on the fence. About a 6.4.
 

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Great write up. Your experience is similar to mine, only my TT is 30' and just under 9000 pounds. Biggest problem at times can be finding a gas station that I can get in and out with my 52' land train. This is the one advantage the diesel guys have as they can go to the big rig pumps. What really has been surprising is the tollways from Chicago and east that are not very truck/trailer friendly for gassers. The worst is my own state of Illinois using their "oasis" rest stops to fuel. Because of all the curbing surrounding the gas pump area it can be difficult to get out if there are a number of cars in there. But overall I am very glad I went with the big Hemi and 4.10 gears. As you say, plenty of power!
 
Great write up. Your experience is similar to mine, only my TT is 30' and just under 9000 pounds. Biggest problem at times can be finding a gas station that I can get in and out with my 52' land train. This is the one advantage the diesel guys have as they can go to the big rig pumps. What really has been surprising is the tollways from Chicago and east that are not very truck/trailer friendly for gassers. The worst is my own state of Illinois using their "oasis" rest stops to fuel. Because of all the curbing surrounding the gas pump area it can be difficult to get out if there are a number of cars in there. But overall I am very glad I went with the big Hemi and 4.10 gears. As you say, plenty of power!
One thing we have going for us in the NW. All the stations on the way were setup for trailers. Multiple had RV islands with gas/diesel.

Just a ton of rv's boats and horse trailers, so everyone is geared up for it
 
Great write up. Your experience is similar to mine, only my TT is 30' and just under 9000 pounds. Biggest problem at times can be finding a gas station that I can get in and out with my 52' land train. This is the one advantage the diesel guys have as they can go to the big rig pumps. What really has been surprising is the tollways from Chicago and east that are not very truck/trailer friendly for gassers. The worst is my own state of Illinois using their "oasis" rest stops to fuel. Because of all the curbing surrounding the gas pump area it can be difficult to get out if there are a number of cars in there. But overall I am very glad I went with the big Hemi and 4.10 gears. As you say, plenty of power!
You are close in size to mine, we have a TT that is 34.5 feet total length, and around 9000 pounds at camping weight. Some gas stations just can not handle that much rig.
 
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