2nd Gen Non-Engine/Transmission something old something new

[champspa]

tried something for a test today was pulling my trailer and tractor about 16k coming to a grade that I normally don't have enough power for . normally I would be going about 60 mph, the speed limit , so today I took it up to 71 or 72 about 2k rpm . that truck humped it up that grade and never even saw it . I thought this truck was at max torque at 16 hundred rpm man I'm telling you that I found a new truck today. tell me something about this new find if you can .

 

[cerberusiam]

What more is there to tell? TQ peak as installed in the truck has always been right around 1900-2000 rpms on any 12V or 24V. Standard prcocedure to run them at 2000-2100 to stay on the front side of the TQ when working them hard.

You evidently just got some bad info, the TQ peak never ever been at 1600 rpms.

 

[hsmith]

I believe it. Mine pulls a lot better at 2k. That is, before I changed back to stock sticks last week. Gonna give it a test again soon.

 

[HBarlow]

Any Cummins or Dodge Ram specifications or literature clearly shows torque peak on 12 valve engines occurs at about 1500 then tapers off as rpm increases. On 24 valve engines including HPCR engines peak torque begins at 1500 or 1600 rpm, depending on programming, and remains flat to about 2700 - 2900 rpm again, depending on programming.

The engines produce more horsepower at higher rpm and allow the torque rise of a diesel engine to work in the driver's favor if road speed or engine rpm are higher at the bottom of a grade when starting the climb.

If a heavily loaded truck hits the bottom of a hill at only 1600 rpm in a higher gear the engine immediately falls off the torque curve as it naturally slows as it begins a hard climb.

 

[hsmith]

^^^
I agree with cerberusiam. Mine is a dog at 1600. Was before mods.

 

[RustyJC]

That's one of the big advantages of 4. 10 gears when towing heavy. With the NV5600, my 2002 was turning 2000 RPM @ 60 MPH and 2350 RPM at 70 MPH, so it had no problem pulling a 16,000 GVWR 5th wheel up most grades in 6th gear where torque rise was working in its favor.



Rusty

 

[champspa]

I've had this truck a long time and it pull my stuff most every weekend . Last year my brother and I were going to CT. to get a OC46 loader about 8k,the gooseneck weighs 6k. we were rolling up 84 thru Pa. ,just to avoid 95 traffic around Washington and Baltimore . After we picked up the loader just north of Bridgeport and headed home I kept the pedal to the metal,the hills didn't slow us a bit, around 2k rpm . I didn't pay attention to it because the hills on those interstate weren't known to me and it didn't pull us down . I just thought it was a light load . Well yesterday I tried it around here on hills that I know take a lot of pull for my ol 96 and wow . just hate to go that fast over the speed limit where I know the local sheriff hides and would love to check the depth of my wallet .

 

[cerberusiam]

just hate to go that fast over the speed limit where I know the local sheriff hides and would love to check the depth of my wallet .

That ends up being the problem with the 3. 55 gears. They are just too high to provide the correct rpm range at the slower speeds. Lack of gears over 1:1 is also a big bugaboo. They are much better suited to the speeds of the western road systems where 70-75 is the norm. There is a reason they came with the short tires from the factory but even that was not enough to compensate. The 4. 10 gear sets and a taller tire were a much better combo for towing and trade off for mileage.

 

[NIsaacs]

I'm telling you that I found a new truck today. tell me something about this new find if you can





Yes, the Cummins loves 2100 rpm. With a 4spd it is hard to get a rear axle ratio that shines, towing and running empty. I would not want 4. 10's with anything less than a two overdrive transmission, they are just too slow for one overdrive. The 3. 55's and stock tires work fine with my '01 and 6spd manual. 5th gear is awesome for pulling hard.



I have a short 8% grade that I haul hay over (25,000 lbs gcw). If I hit it at 70 mph in 6th I can pull it or 60 mph in 5th I can pull it but if I hit it at 40 mph, it would require 4th. Speed/momentum is great for a short hill but doesn't help on a long grade, now it takes brute power.



Nick

 

[HHhuntitall]

5th gear is awesome for pulling hard.

It's not a sin to downshift. If you drove a Ford, you'd be used to it.



I'd rather run in direct and have the option for cruising in overdrive, than have no option for gearing up. I run my KW in 15th gear if it will pull it, and if it won't, I downshift. It prevents overyly high EGTs, excessive water and oil temps, and give me the power I need with the higher gears. I like the fact that if I'm empty, and other cattle trucks are passing me running 85 and 90mph, if I wanted to run with them, I could. And with a weevil wagon, which catches little air, when I'm empty, I can get 6. 7-7. 2mpg. That's insanely good for an 80,000lb gvw truck.

 

[BGlidewell]

. I would not want 4. 10's with anything less than a two overdrive transmission, they are just too slow for one overdrive.
Nick

:-laf :-laf My truck accelerates 50-100 in seconds. Its a hoot to see the look on the unsuspecting rat racers who think cutting off trucks is easy.