Engine/Transmission (1994 - 1998) engine sweet spot

[SPatyna]

If any one has TDR issue 33--pg30 or issue47--pg103 could someone please post the sweet spot / rpm that a 12 valve cummins should run at for torque etc. I have 94 Ram and just installed 4:10 gears as i pull a fairly heavy 5th whl. , truck is auto/bd#6plate/boost orifice@29#/K@N/ no cat / superturbo muffler/autometer gauges/ Truck has never been dynoed ,does anyone have an approximation of what HP/Torque it might have Thanks --- :-{} :-{}

 

[Rams-n-Hogs]

The sweet spot on mine is right around 2000 rpm. Can't help with the hp estimate, though, as mine is a 5-sp with a #10

 

[DogDiesel]

Mine pulls good between 1900 and 2200. Hard to discern difference in this range.

Wayne

 

[Gene Arnold]

I saved a copy of Cummins Power Booster News, Summer/Fall, 2000. It has an article that covers the subject. Here's the pertinent information from that newsletter: "We suggest you run the twelve valves at 1700 to 2000 rpm for best fuel economy and 2000 to 2700 for optimum performance. "



FYI it also notes, "The 24 valves run best at 1900 to 2300 for fuel economy and 2400 to 3200 for performance. We're finding that the 2000 and 2001 models like to run at even higher engine speeds. RPMs in the mid-2000 ranges tend to get better mileage. When a driver runs at lower speeds he becomes aggressive in the throttle and goes through periods of acceleration and deceleration which use more fuel. We see this same occurrence in the semi-trucks as well. "



My '96 with a 4:11 runs very nice at 2100 (which is right at 62 mph on the speedometer).



Gene

 

[SPatyna]

Thanks for the reply Gene as i notice your online. It seems my truck runs around 1750 to 1850 rpm @ 62 mph(100km. /hr) since i have switched to 265-16 rubber all around as it seems to fill out the wheelwells moreso than 245"s, but my rpm will be a twitch lower at any given speed. Had to switch to a35 tooth speedo gear in trans to correct mph. Reg: fuel plate , i always thought i was running a#10 plate but i checked BD's site and the #6 is 230hp/605torque this is what i'm running. thanks again SPatyna.