Need some advice, gearing/fuel mileage.

[MikeRP]

Hey

I know we have a big thread on fuel mileage going. I’m considering a 2020 Ram 3500 Crew Cab with the HO Cummins/Aisin and it has the 4.10 gears and it’s a dually. On a test drive it appeared to be doing around 2000 rpm at 70 mph.

My 2018 3500 is a SRW SB with the HO Aisin and it gets 18-20 in mixed driving and 11 mpg towing my 14,500 lb fifth wheel with the 3.42 gears.

Looks like these sales guys are ordering 4.10’s on everything but I could go w 3.73 gears and hopefully some better fuel mileage.

I tow usually around 65-68 mph. Like I said any ideas on the fuel mileage for this new truck? I live in Ohio and I try to generally stay within the speed limits.

[C_Schomer]

I have had two DRW trucks with a 4.10 gears and my 12 DRW has 3.73 gears and I am really liking them. They handle my 15KRV fine in the Colorado mountains and they are great for my occasional unloaded highway trips. Craig

[Grit_dog]

Cummins12V98 wrote:
Yessir it was a compliment.

Don’t get talkin about ‘spensive fuel too much. Some here get pretty triggered over it!!
Lol

[BackOfThePack]

4x4ord wrote:

otrfun wrote:

4x4ord wrote:
According to the BSFC map for the 6.7 Cummins that Shiner posted on another thread the 3.42 pulling in 5th vs 4.10 in sixth yield very similar MPG while towing. 3.42's should yield close to 10% better fuel economy while running empty at virtually any highway speed. Again, according to the same BSFC map, towing with 3.73 gears at 65 mph should offer a slight advantage in MPG over either 3.42's or 4.10's. Empty the 3.73 will fall half way between 3.42's and 4.10's . . .

"3.42's should yield close to 10% better fuel economy while running empty at virtually any highway speed" vs. a 4.10. Interesting. Not what I've experienced.

Are you making these observations based on BSFC maps of the crankshaft output of a Cummins in conjunction with gearing charts?

Or, are your observations based on BSFC maps formulated and based on on-the-road tests of production-ready, OEM Ram trucks? If so, I'd be very interested in seeing these. Could you supply a link? Thanks.

Like I said, my numbers are based off the BSFC map that Shiner had posted. I just got back from making 2 highway trips where I was able to set the cruise at 45 mph and drive uninterrupted for both trips. The first round trip was performed in 6th gear at about 1100 rpm and the truck got 28.3 mpg. The second trip was performed in 5th gear at about 1400 rpm where it got 25.3 mpg. I would challenge you to do something similar with your Ram ..... I'd be absolutely amazed if the Cummins engine doesn't give very similar results.

[Cummins12V98]

Yessir it was a compliment.

[MFL]

Cummins12V98 wrote:

MFL wrote:

MikeRP wrote:


Escalades are one of the best values on the used market. In three years that $90000 Caddy will be worth $35,000. It can run 300000 miles also but it won’t do that with the first owner. I’d bet 90% of those first owners never see 100,000 miles.

I am a low miles guy. I have purchased quite a few new vehicles. I have never put 50K on any of them. I have only replaced the tires on one vehicle, at 48K, and traded it shortly after. I have a long time family friend, that owns 2 Ford dealerships, a Ram/Jeep dealership, and a Chevrolet dealership. The farthest is 100 miles from me. He and his two sons, own/operate these businesses. They give me a family friend discount, on new vehicle, as well as a more than fair trade on my used. I normally own a car, SUV, and a truck, so mileage is spread out.

I've never worried about mpg, and usually use non-ethanol premium in my truck, always when towing heavy. I do notice the mileage on the display, but never calculate otherwise.

All above, just my experience, doesn't mean I'm doing things right!

Jerry

A true radical!

Well...this can be taken several ways! Coming from a person with similar convictions, likely a compliment!

[Cummins12V98]

MFL wrote:

MikeRP wrote:


Escalades are one of the best values on the used market. In three years that $90000 Caddy will be worth $35,000. It can run 300000 miles also but it won’t do that with the first owner. I’d bet 90% of those first owners never see 100,000 miles.

I am a low miles guy. I have purchased quite a few new vehicles. I have never put 50K on any of them. I have only replaced the tires on one vehicle, at 48K, and traded it shortly after. I have a long time family friend, that owns 2 Ford dealerships, a Ram/Jeep dealership, and a Chevrolet dealership. The farthest is 100 miles from me. He and his two sons, own/operate these businesses. They give me a family friend discount, on new vehicle, as well as a more than fair trade on my used. I normally own a car, SUV, and a truck, so mileage is spread out.

I've never worried about mpg, and usually use non-ethanol premium in my truck, always when towing heavy. I do notice the mileage on the display, but never calculate otherwise.

All above, just my experience, doesn't mean I'm doing things right!

Jerry

A true radical!

[MFL]

MikeRP wrote:


Escalades are one of the best values on the used market. In three years that $90000 Caddy will be worth $35,000. It can run 300000 miles also but it won’t do that with the first owner. I’d bet 90% of those first owners never see 100,000 miles.

I am a low miles guy. I have purchased quite a few new vehicles. I have never put 50K on any of them. I have only replaced the tires on one vehicle, at 48K, and traded it shortly after. I have a long time family friend, that owns 2 Ford dealerships, a Ram/Jeep dealership, and a Chevrolet dealership. The farthest is 100 miles from me. He and his two sons, own/operate these businesses. They give me a family friend discount, on new vehicle, as well as a more than fair trade on my used. I normally own a car, SUV, and a truck, so mileage is spread out.

I've never worried about mpg, and usually use non-ethanol premium in my truck, always when towing heavy. I do notice the mileage on the display, but never calculate otherwise.

All above, just my experience, doesn't mean I'm doing things right!

Jerry

[SweetLou]

Cummins12V98 wrote:
"I am. Personally I don't go through any more fuel than the average bear."

Same here. Amazing tho how many people trip over nickels!!!

Yup, they forget totally about functionality and reliability. So it cost me $3-4 more bucks to get somewhere towing. Big deal, I can do with out that starbucks anyway. If it is that important to someone, cut your speed down, gear it right, and move on.

[4x4ord]

otrfun wrote:

4x4ord wrote:
According to the BSFC map for the 6.7 Cummins that Shiner posted on another thread the 3.42 pulling in 5th vs 4.10 in sixth yield very similar MPG while towing. 3.42's should yield close to 10% better fuel economy while running empty at virtually any highway speed. Again, according to the same BSFC map, towing with 3.73 gears at 65 mph should offer a slight advantage in MPG over either 3.42's or 4.10's. Empty the 3.73 will fall half way between 3.42's and 4.10's . . .

"3.42's should yield close to 10% better fuel economy while running empty at virtually any highway speed" vs. a 4.10. Interesting. Not what I've experienced.

Are you making these observations based on BSFC maps of the crankshaft output of a Cummins in conjunction with gearing charts?

Or, are your observations based on BSFC maps formulated and based on on-the-road tests of production-ready, OEM Ram trucks? If so, I'd be very interested in seeing these. Could you supply a link? Thanks.

Like I said, my numbers are based off the BSFC map that Shiner had posted. I just got back from making 2 highway trips where I was able to set the cruise at 45 mph and drive uninterrupted for both trips. The first round trip was performed in 6th gear at about 1100 rpm and the truck got 28.3 mpg. The second trip was performed in 5th gear at about 1400 rpm where it got 25.3 mpg. I would challenge you to do something similar with your Ram ..... I'd be absolutely amazed if the Cummins engine doesn't give very similar results.

[BenK]

Decide where in the RPM range you will spend the most time towing and running empty or not towing

Then decide which of the two is more important

Then get the HP/torque curve & final hearing to pavement for your ICE.

The lowest RPM for the HP you will need for the above will tell you what diff ratio best suits your desires

[MikeRP]

ShinerBock wrote:

Cummins12V98 wrote:
"I am. Personally I don't go through any more fuel than the average bear."

Same here. Amazing tho how many people trip over nickels!!!

Yeah, and how they are more than willing to spend dollars elsewhere!

Like how my wife's cousin who thought it was stupid for me to spend money on modifying my truck yet just spent over $90k on a new top of the line Escalade. Total cost of my truck and mods are no where near $90k and I am keeping mine for at least 300k miles while he is probably going to keep his for maybe 100k.

Escalades are one of the best values on the used market. In three years that $90000 Caddy will be worth $35,000. It can run 300000 miles also but it won’t do that with the first owner. I’d bet 90% of those first owners never see 100,000 miles.

[ShinerBock]

Cummins12V98 wrote:
"I am. Personally I don't go through any more fuel than the average bear."

Same here. Amazing tho how many people trip over nickels!!!

Yeah, and how they are more than willing to spend dollars elsewhere!

Like how my wife's cousin who thought it was stupid for me to spend money on modifying my truck yet just spent over $90k on a new top of the line Escalade. Total cost of my truck and mods are no where near $90k and I am keeping mine for at least 300k miles while he is probably going to keep his for maybe 100k.

[Cummins12V98]

"I am. Personally I don't go through any more fuel than the average bear."

Same here. Amazing tho how many people trip over nickels!!!

[valhalla360]

Lwiddis wrote:
"Pulling a trailer in Cali is extremely frustrating."

That's you, KSSS. 55 mph is safer...you see more...you save on gasoline.

Yeah...except no.
- Safest is when traffic is all going at about the same speed. Running 20mph below average you are a rolling roadblock that will tend to cause more accidents.
- 55 vs 60-65...if I want to see something, I pull off and look.
- I actually get better MPG as 60-65 vs 55. The combination of engine and transmission is operating with enough extra efficiency to overcome the increase in wind drag.