2007 Dodge Ram ISB

[damar]

Interesting article in OTR truck magazine. Engine "sweet spot", the rev range where engine is most efficient and usually makes the most power. All info from engine manufacturers and based on 65 MPH. Intennational (power stroke Ford) 1,800 to 2,000 RPM. Cummins ISB--used in medium and light trucks and as the Dodge-Cummins Turbodiesel should cruse at 2,100 to 2,400 RPM at 65 MPG, of course based on rear end gearing. Will be interesting to see what ratios will be available when 2007 is announced.

 

[BILLUA]

I cruise at 2200 Rpm's at 80 mph... @ 14. 5MPG hilly terrain

 

[betterthanstock]

Cummins ISB--used in medium and light trucks and as the Dodge-Cummins Turbodiesel should cruse at 2,100 to 2,400 RPM at 65 MPG

65mpg :--) , Mph



In an UPS truck or school bus, yes.



Empty Dodge p-up, 1500-1600 at 65 would be perfect. Towing, get out of overdrive. These trucks need taller final drive, and towing in direct drive, not overdrive. Overdrive wastes 3% fuel due to gear friction.

 

[Cattletrkr]

So what's the sweet spot for towing in direct. At 60mph I'm turning 2500rpm. I think I need 3. 73's.

 

[Buffalo]

According to Mr. Dennis Hurst of Cummins (known as "The Father" of the 2003-up engines), the sweet-spot is in the 1800-1900 rpm range.



This was from a seminar given by Mr. Hurst at May Madness.



Joe F. (Buffalo)

 

[LesStallings]

1,800-1,900 may be a sweet spot for some, and it works fine for me on fairly level ground (15,000# trailer), BUT for the hills and long grades the sweet spot for my truck is DEFINITELY 2,100-2,200 RPM. I did 20,000 miles cross country last year and had an opportunity for repeated, back-to-back runs. Running around 75 MPH out west was heads and sholders above running at 65 MPH. Again, all this is with a fairly high profile 15K trailer. I'm sure the frontal area of an 8'x8'x34' gooseneck has something to do with it!

 

[klenger]

The "sweet spot" for an engine is not a single small RPM range. It is load dependent. While the "sweet spot" for my truck may very well be around 1600 RPM when I'm empty, I sure can't tow my 10k 5er around in the hills at that RPM. As mentioned above, with a load, the "sweet spot" is around 2200.

 

[WStephens]

Yes if you try to run loaded at 1600-1900 on a grade your EGTs would go up to high. When pulling a grade or head wind loaded you need to use higher rpms so the engine can breath and keep the EGTs down in a safe range.