3.73 Vs 4.10 Real Data

[Ratman6161]

Since this is a debate I see frequently, I thought I'd provide some real world data I've gathered from personal experience with two different trucks pulling the same trailer. The trailer is a Rockwood Ultra lite 2608BS travel trailer. Overall length 29' 8" and approximately 7600# total weight and 1020# tongue weight and using a WDH. I have no interest in debating if I need a 2500 or not or if i need the WDH or not. That is already settled...it's what I've got and I'm happy with it.

1. 2022 Ram 2500 Bighorn with 6.4L Hemi and 4.10 rear end. On one trip, towed 1,528 miles and used 206.208 gallons of gas, all 87 octane E10. Avg MPG=7.41. Worst single tank: 6.73 MPG. Best tank 8.79 MPG. I only included tanks of gas where the whole tank was towing. The truck had about 2000 miles on it at the start of this trip.

2. 2022 Ram 2500 Laramie with 6.4L Hemi qnd 3.73 rear end. Two weeks ago, towed 684.7 miles and used 90.043 gallons of gas. Avg MPG=7.6. Worst single tank: 7.05 MPG. Best tank: 8.21 MPG. Once again, I only counted tanks of gas where the entire tank was towing. As before, all gas was 87 octane E10. The truck had about 1400 miles on it at the start of this trip.

There were other trips with the Bighorn, but I only used the one trip where I had good records.

So now for the opinion part: 3.73 vs 4.10 made no practical difference in towing MPG, at least with my trailer. I don't care about unloaded MPG. This is an HD truck that has a job to do i.e. pull the trailer. 7.41 vs 7.6 is close enough that it could be chalked up to different weather (winds) and terrain. The trips in question were all in MN, WI, IA, IL, IN, OH, and MI so roughly the same terrain and I'm betting that headwinds vs tailwind were the biggest factor. I doubt a heavier trailer would make much difference unless it were a LOT heavier.

 

[Bike_Pilot]

That's great data! How did the driving experience compare?

 

[PaPitt]

What speed were you driving .

 

[Ratman6161]

What speed were you driving .

That's great data! How did the driving experience compare?

I was usually going between 65 and 70 on Interstates but with some 55 to 60 on country two lanes. I don't go over 70 even when the speed limit is higher. 65 to 68 is seems to be a sweet spot as far as MPG goes. On the interstates I was slowing down on the interstates mainly when there were strong cross winds. Head winds are the biggest MPG killer. This is why I wanted to compare two trips with significant mileage since these factors seem to a erase out over a multi day trip.

Driving experience: I didn't find there to be a significant difference. The 3.73 truck seems quicker to need a down shift, but it's not really that noticeable unless you are really paying attention to it. Based on some math I did, at any given en speed and gear, the 3.73 will be at around 200 rpm lower. For example 65 mph in 6th calculates to 2677 RPM on the 4.10 and 2435 RPM on the 3.73. On the 3.73 truck, I remember seeing that RPM of 2400 ish quite a lot. But if the 3.73 had to downshift to fifth, it would jump to 3142. So there are some scenarios where the 3.73 had to down shift and the 4.10 didn't where the 3.73 might be at a higher RPM than the 4.10. But that's getting into over analysis. Might make more difference in the mountains and/or a much heavier trailer? Really splitting hairs for me with my 7600# trailer on the plains. But even so, if I head west I'd just go a bit slower up the passes. And the plains aren't completely flat either. We have plenty of rolling hills that add up.

Having driven both, I don't have any regrets getting the 3.73.

 

[Tulecreeper]

I was usually going between 65 and 70 on Interstates but with some 55 to 60 on country two lanes. I don't go over 70 even when the speed limit is higher. 65 to 68 is seems to be a sweet spot as far as MPG goes. On the interstates I was slowing down on the interstates mainly when there were strong cross winds. Head winds are the biggest MPG killer. This is why I wanted to compare two trips with significant mileage since these factors seem to a erase out over a multi day trip.

Driving experience: I didn't find there to be a significant difference. The 3.73 truck seems quicker to need a down shift, but it's not really that noticeable unless you are really paying attention to it. Based on some math I did, at any given en speed and gear, the 3.73 will be at around 200 rpm lower. For example 65 mph in 6th calculates to 2677 RPM on the 4.10 and 2435 RPM on the 3.73. On the 3.73 truck, I remember seeing that RPM of 2400 ish quite a lot. But if the 3.73 had to downshift to fifth, it would jump to 3142. So there are some scenarios where the 3.73 had to down shift and the 4.10 didn't where the 3.73 might be at a higher RPM than the 4.10. But that's getting into over analysis. Might make more difference in the mountains and/or a much heavier trailer? Really splitting hairs for me with my 7600# trailer on the plains. But even so, if I head west I'd just go a bit slower up the passes. And the plains aren't completely flat either. We have plenty of rolling hills that add up.

Having driven both, I don't have any regrets getting the 3.73.

I have the 3.73 in my RAM 2500. I had (I think) a 4.10 in my Silverado 1500...or whatever the 2000 model year 4x4 had at the time. I got sucky MPG with the Chevy, but it towed real well.

 

[dhay13]

Similar to my experience. Towed an 8100lb TT about 900 miles from Pittsburgh to Baytown, TX with my sons 2018 2500 6.4 4.10's. I went with him and hand calculated 3 tanks in a row. Could go just over 200 miles on a tank but MPG results were 8.04 8.13 and 8.49. Truck had about 60,000 miles on it and brand new stock sized tires, semi aggressive tread

 

[Ratman6161]

Similar to my experience. Towed an 8100lb TT about 900 miles from Pittsburgh to Baytown, TX with my sons 2018 2500 6.4 4.10's. I went with him and hand calculated 3 tanks in a row. Could go just over 200 miles on a tank but MPG results were 8.04 8.13 and 8.49. Truck had about 60,000 miles on it and brand new stock sized tires, semi aggressive tread

I have the 3.73 in my RAM 2500. I had (I think) a 4.10 in my Silverado 1500...or whatever the 2000 model year 4x4 had at the time. I got sucky MPG with the Chevy, but it towed real well.

My current truck...the 3.73 truck...had about 1300 miles on it when I started the trip with it. The 4.10 had about 2000 miles on it when I started the trip with it. So both low mileage and with the standard Transforce AT tires set to. Anufactures recommended pressures. The pressures on the 4.10 truck were 60 front and 65 rear. The 3.73 was 65 frontand 70 rear. Different recommended pressures because of 20 inch vs 18 inch wheels. To 20's need a higher pressure to get their load capacity above the 6390 rear axle rating.


Ram 2500 vs chevy 1500...there are too many differences between the trucks to tell whatthe I pact of the rear end ratio was. I figured my experience was a good comparison because the the other differen es between the trucks were so small.

 

[RAM64373]

I thought I just want to share since I also was thinking converting to 4.10 gear from 3.73. I have the 2019 2500 Hemi 3.73 mega, 4x4, 20 inch wheel BigHorn with a 14000 max tow and 2900 payload . For 3 years I was pulling a TT at 7000 GVWR 30 feet to the beach 50 miles from home. I always come home at half tank(31 gallons). I sold that TT and got a 34 FW using the same truck and the same beach. The GVWR of 14600. Going and coming home 100 miles total , the fuel tank showed half tank was also consumed. I was so surprised that I doubled towing load and maybe 3x my payload but it consumed the same gas at 55-60 mph flat land.

 

[2003F350]

I thought I just want to share since I also was thinking converting to 4.10 gear from 3.73. I have the 2019 2500 Hemi 3.73 mega, 4x4, 20 inch wheel BigHorn with a 14000 max tow and 2900 payload . For 3 years I was pulling a TT at 7000 GVWR 30 feet to the beach 50 miles from home. I always come home at half tank(31 gallons). I sold that TT and got a 34 FW using the same truck and the same beach. The GVWR of 14600. Going and coming home 100 miles total , the fuel tank showed half tank was also consumed. I was so surprised that I doubled towing load and maybe 3x my payload but it consumed the same gas at 55-60 mph flat land.

That's actually not that surprising, mostly because you went from a TT to a fifth wheel. Remember that the airflow with a TT is different from that of a FW, leading to increased frontal area even though the TT is physically shorter.

With a TT, the air comes over your hood, over your cab, then DOWN to your box (or tonneau cover, if you're like me and have one). Then it hits the front of the camper, and depending on how long your tongue is it may have dropped down some as well, so you're hitting probably 60-75% of the frontal area of the camper as well. That's a LOT of increased drag due to air resistance.

With a FW, the air comes over your hood, over your cab, then within 3-4 feet hits the camper, and depending on how tall your FW is, this could be as little as 35-50% of the frontal area. That's a LOT less increase in drag due to air resistance.

Where I'm going with this is, the TT might have been half the weight of the FW while sitting still, but at speed with that much increase in frontal area, your motor may not have seen that much difference.

I've towed TTs and FWs with a lot of different vehicles, and I'd gladly take a FW over a TT any day, because they tow a LOT better.

 

[Ratman6161]

That's actually not that surprising, mostly because you went from a TT to a fifth wheel. Remember that the airflow with a TT is different from that of a FW, leading to increased frontal area even though the TT is physically shorter.

I don't know for sure since I never towed a fifth wheel and havent seen wind tunnel data But I figure whatever kind of camper you have its essentially like a barn door either way aerodynamically speaking. I figure that's why loading my trailer heavier doesn't seem to have any noticeable effect on economy.

Here is an update to my original analysis after recently getting back from a 2000 mile trip from MN to the east and back again.

Without going into the details, I did see a fuel economy improvement on this trip. On the trip at the beginning of this thread, I only had about 2,000 miles when I started out. This time I had about 4000 when I started. Overall for the trip I got 8.4 MPG Vs 7.6 on the earlier trip. I had one tank of gas where I actually got 9.6 MPG. But I attribute that to being on a particularly flat section of interstate, relatively slow speed limit of 65, and a bit of a tail wind. Still, averaged out over the whole trip the MPG did make a measurable improvement. Perhaps its getting better with age? Perhaps I got lucky? Who knows.

On this trip I also got a chance to drive it up and down some significant grades for the first time. Those of you out west might not believe this, but there are some significant climbs and descents in western PA. According to my Mountain Directory app, one of the ones I did in PA was actually a 10% grade where the steepest I ever towed on when I lived in Colorado was Wolf Creek Pass at about 8%. Of course in PA the altitude topped out at only 2100 feet or so so not enough to lose any power. Going 30 MPH down this descent in cruise control and with tow/haul on, had it not been for some sharp curves where I wanted to slow down even more, I could have made it all the way down without touching the brakes. The transmission automatically downshifted as much as it needed to to maintain the set speed. Of course that meant it was hitting 5000 RPM at times, but who cares? Its only for a few miles. Even out west, its not like you are driving around at 5000 RPM all the time. I was really pleased with the way the truck handled this. I think many of the towing tests I see online (TFL I'm talking to you) are doing their viewers a disservice by not using cruise control and just letting the truck do what its programmed to do.