I have 2003 2500 4x4 5.9 turbo cummins eng.I have a 22' trailer, fully loaded with bikes water gas its about 9,000lbs. I have problems going up hills without od.I have a clomplete exhaust and air intake system.Also how fast can I go with out the overdrive while towing my trailer..??
How fast are you able to tow up the hills? If it struggles you might need to manually downshift. Out of OD doesn't limit your speed really. It's the max RPM's you probably want to keep an eye on as well as temps.
The weak link with any oil burner is EGT but if engine is not chipped there is little danger of damage on a long sustained pull. Myself I would limit RPM?s to about 2600 or so on along steady pull I would not take it to the redline and hold it there. Not that it would really hurt it but fuel economy will suffer on redline pulls and why bother just to get up a hill 5 or 10 mph faster when the other side will still be there when you get there?
I think you got it backwards there. Cummins recommends that you operate the engine ABOVE the peak torque rpm (but below max operating rpm) in full throttle conditions.
From the Cummins ISB owner's manual:
Do not operate the engine at full throttle operation below peak torque rpm (refer to engine dataplate for peak torque rpm) for more than 30 seconds. Operating the engine at full throttle below peak torque will shorten engine life to overhaul, can cause serious engine damage, and is considered engine abuse. Cummins engines are designed to operate successfully at full throttle under transient conditions down to peak torque engine speed. This is consistent with recommended operating practices.
Do not operate the engine beyond the maximum engine speed. Operating the engine beyond the maximum engine speed can cause severe engine damage. Use proper operating techniques for the vehicle, vessel, or equipment to prevent engine overspeed.
Check the dataplate on the front of your engine for the peak torque rpm and the maximum operating rpm. When you are climbing hills you want to be in the rpm range above peak torque but below maximum engine rpm. You can be at full throttle for extended periods within this rpm range. If you are below the torque peak rpm when climbing a hill at full throttle, downshift. You can drive as fast as you want with overdrive locked out as long as you don't exceed the maximum rpm.
bother
That is what I said as 2600 RPM (the limit I set) is above its torque peak, not below it. I have driven several commins trucks and know its power curve well. Regardless of ratings, it has peaked by 2000RPM, actual below that in a Dodge. As you increase the RPM near redline, effeciency drops as pumping losses increase resulting in higher fuel consumption for the load on it. In my younger years I used to help a inlaw farm and I always ran tractors a few 100 RPM above rated torque peak and that way they would slug though tuff spots real good and fuel consumption was lower too. If you worked it near the redline as my inlaw did sometimes, it would pull down more in tuff spots and use a bit more fuel and not sound as "happy" either
My mistake, I was looking at the HP/RPM ratings, not torque.
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