Pyrometer and diesel trucks

Interesting to read the responses here. I've got an '07 5.9, pretty much same as the OP's truck. I put gauges on a long time ago and kept the truck stock for a long time. You will be amazed how hot the EGTs on this motor will get in stock form. I've had mine at 1425 when I chickened out. I didn't figure I could hurt it in stock form but that seemed hot enough, haha! Contrary to popular belief, downshifting and winding it up actually produces higher EGTs. I've seen the hottest in the 2700rpm range. At lower rpm the computer is programmed to not give as much fuel and it is virtually impossible to get EGTs too high by means of lugging with the auto tranny.

I really like having my gauges, just gives me a little extra info on what the truck is doing. Boost/Tranny/Pyro. As far as cooldown goes, think of it like this: How many people out there who nothing about these trucks drive the wheels off them and never let them cool down and they just keep going? I let mine come down to around 350, but if you're waiting for 300 degrees, you'll be waiting for a while. Seems like wasted time and fuel to do that.

Now, since I've put the Smarty Jr. on, my EGTs are much lower at WOT and towing, but they do come up higher down low now. With reduced EGTs that temperature is now inside the cylinder so I've made a lower EGT limit for myself. That's another topic though.

Getting the temp info is a smart move. I have a 2006 CTD like you and have the older EDGE/Attitude computer with EGT. I use it to monitor EGT, boost, tranny temp, and load percentage. EGT temp has a warning alarm at 1350 degrees, and tranny temp warning at 230. You will probably reach these temps while going up some of the steep parts of the WA Cascades depending on how you drive. These temps are about the max you want to be seeing, but the truck doesn't go into limp mode on the tranny until 265ish and not sure how high you can go on EGT's. With the 48RE 4-speed auto, just use the O/D Lock-out and you can climb the hills in 3rd as fast as you want. The gauges tell if you are pushing it too much (100% on the Load Percentage), or if there is still room to go faster (90% on the Load Percentage).

Going down the mountains is another story --- does the trailer have brakes? Surge or electric? An exhaust brake is awesome but you have to be carful to not overheat the surge brakes on the downhill.

JumboJet wrote:

My 2008 CTD is stock and I have EGT/Boost/Tranny gauges. I have pulled heavy from coast to coast and border to border and my EGTs have never ever gone over 1250.

One of the things I use the gauges for is to monitor fuel efficiency. The higher the boost, the more fuel that is being burned. Much like the vacuum gauges on the 1966 Chevrolet Impala.

I have also driven coast to coast and the Coquihalla Hwy in BC will easily get your EGT above 1300 if you maintain the speed limit (110 km/h) on the climb through the snow tunnels. It is a long hill. If I slow to 60 mph then I do not get over 1250. I have run the hill in stock, fuel economy and tow tune and will exceed 1300 in all three if I maintain the speed limit. I will also shift the tranny into 4th to lower EGT and fuel consumption. There are also a few passes in Montana, Wyoming and Utah that if you run at the speed limit (75 mph) you will exceed 1250. I usually travel at 60 mph, but now and then I like to see how the truck pulls on different grades:D. The question I have been debating is whether to put on a larger exhaust to lower EGT or just slow down? The down side of a larger exhaust is drone and loss of back pressure for descending hills.

ejfranz wrote:
Even with a stock setup you can exceed your recommended egt in mountain passes. Shifting down will lower the egt, but raise the auto tranny temp. I also wait for the egt to drop down to about 300 before shutting down.

My 2008 CTD is stock and I have EGT/Boost/Tranny gauges. I have pulled heavy from coast to coast and border to border and my EGTs have never ever gone over 1250.

One of the things I use the gauges for is to monitor fuel efficiency. The higher the boost, the more fuel that is being burned. Much like the vacuum gauges on the 1966 Chevrolet Impala.

Since adding the Westach dual EGT/boost in '03 I've discovered in 100-110 degree temps in the summer at 75-80 mph on a interstate and long trip with a empty truck it can take 15-20 min of idling before safe shut down temps (300 before turbo) are reached.

I see sustained 1250 degree max temps for long periods from Cummins supported websites and 300 degree pre turbo for shut down as target temps. I've seen egt temps approaching 1300 degree pulling my 12' 10" tall flat front square corner older 5th wheel trailer in western KS/OK fighting a 35-38 mph head wind for several hours trying to maintain 65 mph. I backed off a bit when temps ran above 1275 degrees.

I also use the boost/egt readings to get the best mpgs possible and as trouble shooting tools.

On a 12v at pre turbo 1200. Can go higher ,but don't want to hold there too long.

At what EGT do you get concerned? I have the gauge but what high temp do you worry?

ejfranz wrote:
Even with a stock setup you can exceed your recommended egt in mountain passes. Shifting down will lower the egt, but raise the auto tranny temp. I also wait for the egt to drop down to about 300 before shutting down.

One of two main reasons I went with a manual tranny; temps when driving mountains and engine braking.

Even with a stock setup you can exceed your recommended egt in mountain passes. Shifting down will lower the egt, but raise the auto tranny temp. I also wait for the egt to drop down to about 300 before shutting down.

Tamnative wrote:

12V Cummins wrote:
stock, no worries. Not stock get gauges

This pretty much says it but they do help after a long haul to let you know when you can shut down,or just let it idle for 5 or so min. before shutting down.

If it takes you 5 minutes or so to get off the freeway, through the surface streets and to a parking location, that serves as well for the cool down period. Just about any driving where you are not in top gear is going to be a very light load on the engine and the extra air flowing over the radiator as you drive surface streets is going to cool down enough.

And just to make it clear what it is you are trying to cool down; Diesels have turbo chargers, these are run on exhaust gasses. Those parts get hot and they are lubed with oil. If those parts stop moving, the oil that remains in contact with them will coke up and over time will build up. By running the engine with the exhaust gasses at cooler temps, like idle or low load speeds, those parts cool off enough so that the oil won't coke.