Ram 3500 MPG test

4x4ord wrote:

Cummins12V98 wrote:
4X I did lockout 6th on my 11 DRW with 3.42’s. On flat ground the mileage was the same at 62. It performed better overall leaving it in 5th. No down shifting on hills that way.

Mor important would be to know what my RAM would be turning if I had the same geared trans as the Ford 10 speed with my 4.10’s at 70 mph.

I'm not understanding what you're asking. The Ford 10 speed has a .632:1 gear ratio in 10 th gear .... same as your Aisin in 6th. So if you swapped the 10r140 for your Aisin it wouldn't change your 70 mph engine rpm.

Ah I did not know that. I assumed it would have been running lower rpm than mine.

So one more question. Did the ford have 4.10’s?

4x4ord wrote:

ShinerBock wrote:

4x4ord wrote:


To get an idea as to what the 10 speed would do for the Cummins all you'd have to do is drive your Ram down the road towing a heavy load at 1700 rpm in high gear and reset your milage meter...... drive a few miles and see what your average trip mileage was. Then go back and drive the exact same stretch of road at the same speed in 5th gear (about 2095 rpm) and see what your trip meter says for mpg. There is always people claiming they lock out high gear while towing and don't see any loss in mileage. I've never believed these claims, but at the same time I don't think the increased fuel usage is going to be anywhere near 30%.

The same way a shorter rear gear ratio will provide better fuel economy when loaded, so will will a shorter trans gear when loaded. Don't believe me then ask a Ford engineer.

"Also consider that the axle ratio is only a portion of the overall pickup gearing. Manufacturers spend a lot of effort on powertrain matching. "Powertrain matching is really a systems approach," says Dennis Slevin, vehicle engineering manager, Ford Commercial Vehicles. "It is the engine, transmission, axles and tires working together. It is the effective ratio of engine power transmitted all of the way through the drive system to the ground."

He adds, "From our perspective there are interconnected reasons to choose optional axle ratios -- if you are hauling heavy loads with large trailers in hilly terrain, and you do a high frequency of towing." Consider a PowerStroke 6.7-liter diesel that offers a choice of a 3.31, 3.55, 3.73 or 4.30 axle ratio. "The 3.31 might be capable of towing the trailer. But if you are towing the majority of the time, you probably want the 3.55 because it will tow better and provide better fuel economy loaded.""


How to Pick Pickup Truck Axle Gear Ratios to Improve Performance

If you are in to high of a gear and "lugging" the engine to overcome the load, then the engine is not operating efficiently. The most efficient rpm is always changing based on speed and load. Towing 7-14k at low speeds of 60-70 mph, then it is best to lockout 6th to keep you at more efficient rpms. At speeds above 70, the 6th becomes more efficient.

I understand this stuff very well. As a rule for any speed you are travelling the highest gear the engine will pull the load in is the gear that will give you the best fuel economy. There might be some isolated segments in an engine's lower rpm range under certain power demands where running the engine a little faster might gain you 3 or 4% better fuel economy. The Cummins engine might like 1900 rpm better than 1700 pulling a load like TFL was pulling. If one rpm is going to be better than the other it's not going to be better by a very significant margin.

I was commenting on this "There is always people claiming they lock out high gear while towing and don't see any loss in mileage. I've never believed these claims..." Believe it or not, you can gain fuel economy by using a shorter gear ratio depending on your speed, load, and the engine's sweet spot. Even the Ford engineer agrees.

And yes, per Cummins, the 6.7L's sweet spot is 1,900-2,100 rpm, not 1,700.

ShinerBock wrote:

4x4ord wrote:


To get an idea as to what the 10 speed would do for the Cummins all you'd have to do is drive your Ram down the road towing a heavy load at 1700 rpm in high gear and reset your milage meter...... drive a few miles and see what your average trip mileage was. Then go back and drive the exact same stretch of road at the same speed in 5th gear (about 2095 rpm) and see what your trip meter says for mpg. There is always people claiming they lock out high gear while towing and don't see any loss in mileage. I've never believed these claims, but at the same time I don't think the increased fuel usage is going to be anywhere near 30%.

The same way a shorter rear gear ratio will provide better fuel economy when loaded, so will will a shorter trans gear when loaded. Don't believe me then ask a Ford engineer.

"Also consider that the axle ratio is only a portion of the overall pickup gearing. Manufacturers spend a lot of effort on powertrain matching. "Powertrain matching is really a systems approach," says Dennis Slevin, vehicle engineering manager, Ford Commercial Vehicles. "It is the engine, transmission, axles and tires working together. It is the effective ratio of engine power transmitted all of the way through the drive system to the ground."

He adds, "From our perspective there are interconnected reasons to choose optional axle ratios -- if you are hauling heavy loads with large trailers in hilly terrain, and you do a high frequency of towing." Consider a PowerStroke 6.7-liter diesel that offers a choice of a 3.31, 3.55, 3.73 or 4.30 axle ratio. "The 3.31 might be capable of towing the trailer. But if you are towing the majority of the time, you probably want the 3.55 because it will tow better and provide better fuel economy loaded.""


How to Pick Pickup Truck Axle Gear Ratios to Improve Performance

If you are in to high of a gear and "lugging" the engine to overcome the load, then the engine is not operating efficiently. The most efficient rpm is always changing based on speed and load. Towing 7-14k at low speeds of 60-70 mph, then it is best to lockout 6th to keep you at more efficient rpms. At speeds above 70, the 6th becomes more efficient.

I understand this stuff very well. As a rule for any speed you are travelling the highest gear the engine will pull the load in is the gear that will give you the best fuel economy. There might be some isolated segments in an engine's lower rpm range under certain power demands where running the engine a little faster might gain you 3 or 4% better fuel economy. The Cummins engine might like 1900 rpm better than 1700 pulling a load like TFL was pulling. If one rpm is going to be better than the other it's not going to be better by a very significant margin.

Real world empty run for Los Wages to Denver. Average speed was 70 MPH and 80 in some stretches. 15 MPG My SRW with 3.42 would have been around 19 MPH or a little higher. https://www.youtube.com/watch?v=9sFgt4rkLBg

Cummins12V98 wrote:
4X I did lockout 6th on my 11 DRW with 3.42’s. On flat ground the mileage was the same at 62. It performed better overall leaving it in 5th. No down shifting on hills that way.

Mor important would be to know what my RAM would be turning if I had the same geared trans as the Ford 10 speed with my 4.10’s at 70 mph.

I'm not understanding what you're asking. The Ford 10 speed has a .632:1 gear ratio in 10 th gear .... same as your Aisin in 6th. So if you swapped the 10r140 for your Aisin it wouldn't change your 70 mph engine rpm.

4x4ord wrote:


To get an idea as to what the 10 speed would do for the Cummins all you'd have to do is drive your Ram down the road towing a heavy load at 1700 rpm in high gear and reset your milage meter...... drive a few miles and see what your average trip mileage was. Then go back and drive the exact same stretch of road at the same speed in 5th gear (about 2095 rpm) and see what your trip meter says for mpg. There is always people claiming they lock out high gear while towing and don't see any loss in mileage. I've never believed these claims, but at the same time I don't think the increased fuel usage is going to be anywhere near 30%.

The same way a shorter rear gear ratio will provide better fuel economy when loaded, so will will a shorter trans gear when loaded. Don't believe me then ask a Ford engineer.

"Also consider that the axle ratio is only a portion of the overall pickup gearing. Manufacturers spend a lot of effort on powertrain matching. "Powertrain matching is really a systems approach," says Dennis Slevin, vehicle engineering manager, Ford Commercial Vehicles. "It is the engine, transmission, axles and tires working together. It is the effective ratio of engine power transmitted all of the way through the drive system to the ground."

He adds, "From our perspective there are interconnected reasons to choose optional axle ratios -- if you are hauling heavy loads with large trailers in hilly terrain, and you do a high frequency of towing." Consider a PowerStroke 6.7-liter diesel that offers a choice of a 3.31, 3.55, 3.73 or 4.30 axle ratio. "The 3.31 might be capable of towing the trailer. But if you are towing the majority of the time, you probably want the 3.55 because it will tow better and provide better fuel economy loaded.""


How to Pick Pickup Truck Axle Gear Ratios to Improve Performance

If you are in to high of a gear and "lugging" the engine to overcome the load, then the engine is not operating efficiently. The most efficient rpm is always changing based on speed and load. Towing 7-14k at low speeds of 60-70 mph, then it is best to lockout 6th to keep you at more efficient rpms. At speeds above 70, the 6th becomes more efficient.

larry barnhart wrote:
Maybe this story needs to end. chevman

4x4ord wants it to go until everyone confirms that FORD's get 30 percent better mileage.

Why doesn't someone post some real world Fuelly app data that proves it one way or another?

In tow haul my RAM/Aisin/SRW/3.42s will not shift to 6th until over 65 MPH. Last winter 2018/2019 towing the 8K TT verses the 16K 5th wheel the mileage was about the same at 60-62 MPH. This last fall I sped up to 65 and 6th gear and gained MPG with the little TT.

Maybe this story needs to end. chevman

4X I did lockout 6th on my 11 DRW with 3.42’s. On flat ground the mileage was the same at 62. It performed better overall leaving it in 5th. No down shifting on hills that way.

Mor important would be to know what my RAM would be turning if I had the same geared trans as the Ford 10 speed with my 4.10’s at 70 mph.