My 5.2L powered 1997 Ram pulls itself in OD at 70 MPH very well but the engine is loafing along at ~1750 RPM. Add a tall travel trailer and the 318 isn’t producing enough torque to keep a steady 70 MPH in OD (on flat road) at the 1750 RPM. A back of the envelope calculation indicates I need about 40 ft-lbs more torque to keep a steady 70 MPH. More displacement would be the answer if I don’t want to change gears but how much is enough? The easiest swap is to a 5.9L that I have access to, but not sure if the torque output of the 5.9L would be signifi- cantly higher than the 5.2L at only 1750 RPM. Not finding any real information on how much torque these engines produce at such low RPM—so just wondering if you have some idea if worth swapping to the 5.9 or not or if a gear change is still likely needed anyway.
At 1750 RPM, the SMPI 318 cranks out 265 ft-lbs. At the same engine speed, the 360 is more like 288. An additional 20 ft.- lbs. could be picked up by using a better exhaust system: 1992–’93 manifolds, 2¼˝ headpipes, a Flowmaster merge collector, 3˝ outlet into 3˝ hi-flow cat etc. Of course, there’s always a 408. Increase fuel pres- sure for a lowbuck “calibration.”
PS: you didn’t say whether your Dodge Ram is a pickup or B-van (but it makes no difference to my reply).