I just bought a new 2006 2500 Dodge Cummings and I am new to diesels. I am confused about the red line on the tachometer. The red line starts at 2300 RMP and up. The owner's manuel states not to drive in the red line for "long periods of time." How high can I go into the red line and how long is "long periods of time"? I pulled my 26 foot Warrior loaded with 150 gal of water, two quads and 60 gal of gas last weekend and it never got into the red line. I took it easy because I only had 500 miles on the truck when I left and pulled some steep mountains from Phoenix to Flagstaff.

 

"I just bought a new 2006 2500 Dodge Cummings" You gotta know you're going to get grief for that. It's a Cummins, not Cummings. You said your redline starts at 2300 RPM. I believe this should be 3200 RPM? To me, running over the redline for even a few seconds would be too long.

Jim

 

I've never hit the redline, and I dont see why you would under normal circumstances.

 

Forgot my manners . Welcome to the board and congrats on the new truck. Post a picture if you like.

Jim

 

My tack is 3000 and a lot of guys are puttting in the 3-4000 spring kits , but the first thing in mods is gauges , for yours fuel pressure , exhaust temp , if auto trans. trans. temp. , boost , and the 1 to watch the most would be the exhaust temp. and could call red line for temp. 1,250 for a few min. go to your control pannel and fill in the info on your truck so its easyer to help with ? but to get closer to your ? for now these trucks are set up with govener type systems , thats the spring kits for the older trucks [ I,m not sure about yours ] they do this mostly by whats called defueling when you reach the factory limits the fueling to the engine drops off. With a new truck you may want to limit your mods if you want to maintain your warentee , I'm sure the guys with newer trucks will fill in some of the details for the newer trucks.

 

First off, welcome to the board. Secondly, your in the wrong forum. You have a 3rd gen. Thirdly, don't worry about the red line. These engines were designed to run at a specified max rpm for a very long time. Not to mention that there is a rev limiter on these trucks that will not allow you to go beyond what dodge and cummins both deem as a safe max rpm. You really don't need to be shifting at redline unless your racing and even then it's a moot point because your engine is starting to defuel and your losing power. So go out there, hook up to your trailer and yank that thing anywhere you want and don't worry about the engine. Your not gonna hurt a thing.

 

i couldnt have said it better blue

 

Ditto!!!

 

Well from what I have read, the "redline" on the tach for the CRD engines is 3200rpms, the computer governs it to 3500, but the real REDLINE is 4000rpms. In said reading I have heard 3200rpms all day long. Which makes a lot of sense since they use this same engine in boats, which will run full throttle for hours on end.

So like BigBlue said... hook it up and pull away. Don't worry about the engine. It's the rest of the truck you need to worry about

 

my tires broke loose a couple days ago and my Tach jumped to about 3400 RPM and i sure got scared but it was there for less than half a second

 

I think that if you're towing down a grade, and you change down a gear, in order to slow down, you may exceed the max RPMs. At least that's what Dodge says.

John

 

i've seen 3500 upshifting, and 3800 downshifting.. when the engine ecm is controling the fuel, there is NO WAY the engine can overspeed. when downshifting, you can overspeed the engine, but i am happy keeping it under 3800rpm..

 

If your new truck is an auto, forget overreving. There is no way you can possibly overrev it with stock programming. You can't do it with the accelerator pedal, and you can't do it by downshifting because the transmission just won't downshift at an unsafe speed regardless of what you tell it to do. If it's a manual you bought, then the only way you can overrev it is by downshifting it at too high of a speed. Normally I'd advocate staying out of what the factory tach says is dangerous territory, but in this case you can do whatever you want as long as it's not downshifting a manual while going too fast.

 

I think he was asking about the downshifting going too high. If you have a Jacobs E-brake, the E-Brake documentation says not to operate at over 3000 RPM, which is 200 RPM lower than the engine's 3200 RPM redline. Stay within the recommended limits, and you should be just fine. Like John Faughn said above, it would be wise to have a pyrometer mounted to watch your EGT's, especially when towing hills with heavy loads.

 

Guys, Nick is right on 3400 fueling, 3800 braking. 4000 rpm is the absolute max rpm without internal engine modification, Valves, valve springs, cam, etc. Diesel engines are rated on duty cycle. light duty like dmax and powerstroke engines are full throttle 10% dty cyle. Our cummins is medium duty which is like 25% full throttle at factory rated power. Most fishing boats use commercial duty which is like 75% at rated power full throttle. Heavy duty applications are 100% at rated power. Typical ratings for the same engine series tuned and rated would be as follows.
light duty 350 hp at 3400 rpm 10%
medium duty 300 hp at 2900 rpm 25%
commercial duty 250 hp at 2500 rpm 75%
heavy duty 210 hp at 2200 rpm 100%

Figures are not specific to any engine only the concept. ks