I noticed the rpm gauge only goes to 3200+/-. When I am at highway speeds it seems that I would reach the designated red line on the gauge relatively quick. How should I interpret the rpm gauge? I am used to going 70 mph and the gauge reading 1600+/- rpms on the last 02' 1500 I had. Should I be concerned about 2000 rpm's @ 65 mph? I've read other posts about going faster and wonder what kind of rpm's they are turning.

 

Redline is upper safe limet. You can pull all day at 2900- 3000 on hills etc I think you'll find running at redline in high will be way over a desired speed. On a steep hill towing12000 I pick the gear it'll pull the grade in anf then run 2200-2500

 

weathervane, how often do you red line the engine? I'm guessing you've got an auto tranny in it? I'm running 4.10 gears w/6-shooter and can't remember the last time mine got close to red line.

My truck runs about 65 @ 2100.

Remember this isn't a gasser. I've found that keeping the rev's around/under 2k will give the best fuel mileage.

 

bulabula,
I never really approach redline it just seems to me that you could get there rather quickly. Again I'm comparing this new experience with those of a past gasser. I guess my real query is what happens when I'm rolling through georgia and north carolina where the speed limit is 70 posted plus, where are my rpm's at that point? It would seem as I approach those speeds(70 -80) the rpms would approach that "redline". I'm I just being ignorant? Bottom line.....am I going to be able to keep up w/ traffic w/o affecting the truck in some fashion? I know it sounds strange, but just had to ask.

 

I know that when I've got alot of miles to cover in a short period of time, I'll keep the hammer down with the best of them. When the truck was brand new, I drove it off the dealers lot and onto the interstate with the cruise control set at about 77mph or so for hours on end. I was turning about 2200 RPM at that speed, and while fuel economy suffers a bit at that RPM, the increasing engine noise would become one of the first things I will notice when moving above that RPM.

Late one night on a long bridge with no one else around, I decided to see how close to the 120mph on the top of the speedometer I could get. I hit 100mph on the speedo just about the same time as 3000 RPM on the tach. It ran just as straight and solid as one could expect from 6,700 pounds moving at that speed. Because the redline is 3200, I decided that I had seen enough and backed off. This is in a 48RE 4 speed auto with 4.10 gears, no telling what kind of numbers a CTD paired with a 3.73 rear end could post. The '03 service manual says the 48RE auto has a 0.69:1 gear ratio in 4th, while the NV5600 only makes it down to 0.73:1 in 6th gear.

 

My 4.5 with the auto and 3.73s runs 108 @ 3200 rpm when the fuel shuts off. Doing the key trick won't give much more mph because this brick is running out of horsepower. Besides, I'm not too comfortable revving these Cummins much past 3500.

 

My first CTD also!
Yes it seems strange to me also not building revs to make power!?
I run mine 2200rpm @70mph.
I've never run over 90mph and was too busy to look at the tach. Just noticed the wife grabbing the chicken bar!
I'll gladly run it up to the redline and let you know.

 

Thanks guys, After thinking about it today i realized what a stupid notion.

 

I was told all the ctd HO- had a shutdown chip set at 95 mph??

 

a "shutdown chip"? What's that?

The engines are limited by the "high speed govervor". It will cut fuel at 3500rpm regardless of how fast you are going. They all do over 100.

 

You were told wrong. Who said that anyways?