I'm getting ready for our first big trip with fifth wheel, out west... up steep grades at high elevations. I've installed my pyrometer and boost gauges. transmission and engine temp gauges came stock. My question is this... suppose I'm pulling up a looooong mountain slope (say for 20 minutes)... What is the MAXIMUM sustained reading I'd want to see over the course of 20 minutes for all these gauges? Here are my guesses:

Pyrometer (EGT): 1200
Transmission Temp: 200
Engine Temp: 240
Boost: 15

Note: I'm running sythetics (AMSOIL) throughout truck.

What would be the maximum levels that YOU would feel safe running for a sustained period of 20 minutes? In other words, at what threshold would you feel that you needed to start backing off the pedal? If my figures are high, I'd rather back down sooner and be safe. If my figures are low, then I'd rather not slow down if I don't need too. Trying to balance safe usage with efficient travel.

Thanks in advance...
Paul.

What does your trailer weigh? Unless your CGVW is upwards of 20K (looks like no programmer) I suspect you won't push it too much.

What does your trailer weigh? Unless your CGVW is upwards of 20K (looks like no programmer) I suspect you won't push it too much.

CGVW will be about 19K - 20K. I will not be using a programmer-- maybe next year. Load/programmers may effect HOW intense the truck is running, but they shouldn't effect the overall LIMITS. If a stock/solo truck hits a sustained EGT of 1400 degrees via hard driving, or a chipped truck pulling a trailer hits a sustained EGT of 1400 degrees by pulling up a mountain at 10000ft, what would be the difference? It's still doing the same damage to the truck. So my question had to do with 1400 degrees, or... 1300 degrees, or...whatever. So the question(s) remain: what are the safe limits? --Paul.

Paul, you always want to keep the EGT out of the red on the long steep hills. You will have no problem doing that most places out here. When the temp gets near redline go to 4th and stay there until you hit the top. You might have to slow down a little. I haven't been on a hill that was 20 minutes long. You will not see over 210 engine temp if everything is running normal. The only time I see 200 on the trans temp is very slow heavy towing or stop and go. Boost will vary on every hill and seldom will be 15 lbs. for long periods unless you just have to go 70 up every hill.

Agreed, the use of a programmer doesn't change the limits. But if you're running stock with a light load, you probably won't hit the limits.

With the weights you're running, maybe you will.

Agreed, Rockin. I did a couple checks, and even though the stock Duramax doesn't have an EGT tap, the folks at GM have a LOT of info available to the computer (like fuel rates, temps, RPM's, boost pressure, etc) and from what I've seen, stock programming, the computer begins to defuel and shifts the tranny down or whatever, and rarely sees ANYTHING over 1300-1350'F on EGT's (that was the absolute highest I ever saw, just before the tranny limped). I assume they did proto work with EGT gauges and set up the computer to never need to worry about getting into too high of EGT's stock with all the other info they had available.

However, even moving to a 40hp Predator tune program (while towing), I noticed that I could easily get into the 1450'F with no signs of stopping if I didn't monitor my right foot. That is because the predator just modifies what the report going back to the computer about the actual fuel being added to the engine is, and lets the computer run everything else. Unlike the Edge/Attitude programmer, which actively begins to defuel and change things as you approach preset max EGT's. I was surprised how much even just the lowest (+40hp) setting on the predator affected towing temps. I don't think I want to have to watch it that much (couldn't even leave it on CC for fear of spiking over 1500'F) to tow on the +40hp setting (I am looking for a cheap Edge/Attitude now on Ebay).

Frank, I think Pauls question was WHAT IS THE RED? See, my gauges (and probably Paul's) don't show ANY red areas for boost of EGT's. So your advise of just keeping it out of the red doesn't do him much good. In answer to that, Paul, I would assume that 1350-1450'F on EGT is the "dashed red" part and a hard red above that from what I can read. That means, fine to spike up to 1400'F or so for short times, but keep it below 1350'F for any sustained time.

As for the boost, unless you've put a blower on that rig (grin), you can't really go too high (i.e. there is no real red line you can get to, even with a programmer). Technically, it rarely runs over 30psi for any length of time, from what I've seen, and I think you're safe up to over 40psi from a mechanical stand point...

-JM