RPM "Sweet Spot" for 2014 Tradesman with 6 speed manual transmission

[Reno Dave]

I just finished a 600 mile trip hauling my trailer to the North Coast of California. In my old 99' Dodge Diesel I knew the sweet spot for fuel economy was between 1800 and 2000 rpm's with the boost gauge at 10lbs.. Now, with this new 2014 6.7 it seems the rpm's are lower because of the increased horsepower and torque. While towing (trailer weighs approx. 8000 loaded), I hovered between 1500 and 2100 approx..
My average fuel consumption was 11 mpg.
Any of you folks out there have insight where as to where the "sweet spot' should be?
Thanks,
Reno Dave

 

[RVTRKN]

Whats your rear end ratio?

 

[Deleted member 995608]

Whats your rear end ratio?

Has to be 3:42 unless he changed it himself

 

[Reno Dave]

Whats your rear end ratio?

The rear end ratio is 3:42, 6 speed manual transmission, 4x4, long bed

 

[n7gxz]

I just finish doing a 6000+ mile trip pulling a 24' enclosed trailer, about 2/3 the trailer was lightly loaded and the last 1/3 was loaded with 10 dual sport motorcycles. I was running 55 to 60 mph which puts the RPM about 1600-1700 area (3.73 gears). My mileage ran around 11.8 mpg unloaded or loaded so the weight was not what was cutting my mileage but the aerodynamics of pulling a brick.

Kevin

 

[EDankievitch]

I had found with my 05 that had the 3.73 gears with the 315-75-17 tires that at 70 mph my rpm's would be around 2,000 Wind restance was the biggest issue. Exhaust temp's would run around 750 when towing Mpg's would be around 12-13 with no head wind and 10-11 with a 20 mpg head wind. If I dropped my speed down to 63-64 RPM's around 1675. My exhaust temp would drop down to 650 and the Mpg's would jump up to almost 14. Any slower I would be lugging the engine and the boost would run around 5-7 lbs exhaust 750-800. At 55 if I down shifted down to 5th the boost would jump up to 10-12 lbs but exaust would drop below 600. My Mpg's would jump up to almost 15. Mr Cummins if I remember correctly had found the sweet spot for most diesel engines is 10 lbs boost and less than 600 degrees exhaust temp. That all said best advise install a good set of gauges and drive by them for the best MPG's

 

[Joseph Donnelly]

On the flats, the new engine seems to like 1500-1700 rpm; to pull hills with a trailer (4k to 8k weight), 1700-1900 works.

 

[Newsa]

Agreed 1500- 1700. Where the torque peaks. But it would take you longer to make the trip because you're going 55 mph +/- 2 mph (instead of 65-70)

I had more time on one day of my summer vacay pulling a 5000 lb trailer that sticks up 9+ feet in the air. And got 15-16mpg vs. 11.5 mpg at faster speeds.

Part of that might also be less wind resistance at 55 mph compared to 65-70 mph. But I'm inclined to believe that if I had another gear (7th gear), it would still do very well in the 1500-1700 range. You can tell it's happy there.

 

[Too Tall]

I have found, For fuel economy, the slower you go, the lower the rpm (without lugging), the higher your mpg will be. When you are dealing with a lot of wind resistance, mpg goes up exponentially with increased speed. When pulling my travel trailer, I just slow down, stay in the right lane and enjoy the trip. I make up the time difference with short stops. You'll get there with a lot less stress also. But this is an old man's view. The good news is fuel prices are coming down.