whats the best way to lower egt while towing? I find my self driving by the pyrometer and I have 3/4 of the throttle to go. while hitting 1250* constantly

 

Well, if ya have 8500lbs behind ya daily, here would be my suggestions...if you are talking about having a lot of throttle left to go, it sounds like to me that you are probably on the highway in overdrive (or what seems to be 4th gear in autos to some people). I don't think that you have an overdrive lockout button, but if you do, I suggest locking it out and slowing to about 55mph or so for bigger hills. If you have a manual way of doing this (such as the column), pull her down out of OD and into 3rd for the hills. When you're pulling steep grades with a heavy load behind you, you want your RPMs to be between 2200 and 2500. that will keep your boost high and your EGTs low...when you're on flatter ground, you can afford yourself the lower RPMs to save on fuel because the motor won't lug...lugging, if you didn't know, is the feeling that your engine WANTS to downshift, but just won't...sounded like it is about to bog out, etc and is the PRIME factor leading to high EGTs...unless you're just constantly flooring your truck for no reason with a heavy load behind you which is going to KILL your tranny anyway...ease up to speed and follow the above suggestions and report back with you EGT results.

 

The best way to lower your EGT for any given road speed is to raise the RPM. Instead of pulling grades at 1600 go to about 2200 or 2500. If your temps are still too high you'll have to back off and slow down enough to stay in the safe range.

John

 

ditto on the RPM. I lower my EGT by 300 degrees going from 1600 to 2200.

 

Your tire/gear ration is what is hurting you. The 315's with 3.54 gears are keeping your rpms to low. A set of twins or tire/gear change.

 

X2 on the tire thing, those oversized tires make that 8500# into 10,000#! If you tow 8500# daily then what do you need the big tires for? Go back to stock and you'll see a MPG increase as well.

 

OMG! Do you mean to tell me the almighty Cummins can't pull any load up any hill at 1600rpm? Blaspheme!

Whenever I tell someone that my truck doesn't pull well at 1600rpm,they think I'm nuts. They always want to argue about peak torque,and how thats all that matters with the Cummins.

When towing heavy,RPM is your friend. Not only will more RPM keep the EGTs down,your truck will pull better. With more RPM your truck is making HP to go along with all the torque.

 

Yup! Lock out OD and get use to the sound of higher RPM. The Cummins can handle it all day long at 2500 rpm+..... but it takes some getting use to the sound.
With your tire and rear end combo, do what ever it takes to keep the engine above 1800 rpm at all speeds when towing. But going back to 265/75/16 is really your best choice if towing often.

RJ

 

That is the right answer.

3:73 with your size tires equals a 3:34 ratio. 3:54 with your tires is down in the 3:10 area. I would not run in overdrive when towing. Adding a larger exhaust system would also help some.

Dave

 

I had a 97 215 (modded) and didn't like the 3.54s at all when I went from a 25 to this 31' 5er - the engine was always working too hard usless I kept it wound up. Craig

 

X2 on the larger exhaust, and RPM.

 

I need to keep the big tires because I find my self dragging my concrete pump through sand , mud, up hills, off road, in reverse through horse trails etc. all of which I do in 4 wheel low. probably 2 days out of the week at the least. on top of the 2,000 miles a month on the highway. A gear change sounds like it would be best for me. what size gears can I put in my carriers? and what would put me back to the stock ratio with my 315's?

 

You could go to the 4.10 rear end, which I think might take you too far the other way. Dana has a 3.76(+/-) for their 60 Frt/70 rear axles that might be better. I looked into this option as an alternative to a Cam and to my switching to smaller tires for drag racing.

My source is a customer in your area (Anaheim) and might be worth a call. Unitrax Drivetrains, 714-630-4327.

RJ

 

If you don't want to spend the money for a gear swap use a lower transmission gear and higher RPMs; then use the saved money for fuel on the weekends. As mentioned you may actually see better fuel economy. The disavantage to the axle gear swap is when you are unloaded your engine will be running pretty high RPM running down the hughway at 65-70 mph.

L8r,........dogger

 

Look at my sig and you will see how I handled egt's while towing. I was exactly like you driveing with one eye on the pyro "ALL" the time plenty of peddle left but egts got to hot to fast. There may be a couple of ways to attack the problem but this is what "WORKED" for me. I run about 22K gvw with the ole 92. Get a stage three compresor pump and open up the exhaust. Also get a BHAF. The Cummins has to breath. I went from stock exhaust to 4" from the exhaust brake to the transfer case and 5" with a flow through giant muffler. Renagade Diesel did the exhaust work for me talk to him. I know your truck is newer and there may be a few things different but these things helped trememdously. Can I pull a long steep hill in 5th heck no but it made all the difference in the world. I carry 33" tires and 354 rears. I bought the truck new and didn't expect to tow anywhere near as heavy as I do. I would have gone to a bit lower gearing but runnin empty I like the 354's. I also agree when pullin wind er up. I am still guilty of to low rpm's but if ya keep er spinnin she will run cooler.

The added benny to these mods are the whistle sounds great and she pulls much much much better.

HTHs