I'm sure it must have been discussed, but I couldn't find it. So here goes.


Of course the EGT guage goes up into the red when I put a load on the engine. It come down right away when I decrease the load. But when pulling a good grade, how long can I allow it to remain in the red before getting too concerned? I'm running my Hypertech on the max...should I back it off when pulling? TNX..Snakebite

Would help to know if probe for pyro is in exhaust manifold or post turbo. Also, what are the temp numbers. Makes a big difference.

Tom;


Of course you are right..I forgot to mention the location of the probe. It is in the exhaust manifold on the passenger side. The guage goes from green to yellow at the 10.5 mark, and then to red at the 12.5 mark. Normal operation when pulling the fiver (approx 12-13K) on flat ground at 60mph is around 6-700. When pulling a steep (5%+) grade the pyrometer quickly climbs into the red. It drops back when I let off, but if I keep that up its not long before I'm crawling. There is plenty of Power, but to use it puts me in the red. I'm just not sure how long I can keep it in the red.


Snakebite

Probably differences of opinion here, but I have my temp alarm set at 1280, and I don't like to go over 1325. I think I can run safely at 1250 - 1280 for quite some time. When I am at sea level, I do not see much above 1150 - as I climb, the peak temp will be higher, so at 6000' I can only see 19 lbs boost and 1280 degrees. If I am driving I can add a bit of HP enhancemant on the fly, but everything is dictated by that temp. I hope this provides a bit of guidance.


With my 6 horse trailer, I probably weigh 24k+, and with hay, a whole lot more.Edited by: Horse Trainer

I never let mine go into the red for more than a few seconds, towing or unloaded.

For what ever it's worth, the Edge Attitude comes from them set at 1350. It's worth noting that the Juice will start de-fueling before it hits that temp in order to not exceed it.


I asked Edge about moving the limit up, the response was "I wouldn't do that if I were you..."


I'll be continuing to watch this thread for input from others on the subject because I know it's a critical issue based on my experience with turbocharged aircraft engines. My experience with turbocharged diesel engines and max EGT's is really lacking...http://www.dieselplace.com/forum/smileys/Ermm.gif

I've asked this question before.....My LLY motor is completely stock and I removed the Cat converter. When I pulled my 8,000 lb trailer up a 5-6 % grade I wanted to see what stock programing put my EGT at. WELL, I saw 1410 degrees for at least 4 minutes...................I figured that this 3500 duelly is programed from the factory without gauges and if you didn't have them you would not know when to back off.....So I didn't!!! I am not even close to max towing capacity so I wasn't worried. Yes I think these temps are high, (Pass side exhaust manifold) but GM would have put 4" exhaust on it if it wasn't ever to get that high IMHO. I know lower #'s are better, but I wouldn't worry about going that high again. NOW 1600 DEGREEs................http://www.dieselplace.com/forum/smileys/Ermm.gif


P.S. after 5 minutes the coolant temp got around 230* but the pull was over. Outside temps were 90*. Edited by: KTDURAMAX

KT - I'll bet you went up to Flag. I haven't made that run in the summer, but in March, that is where I have sen my highest EGT. In theory, the oil cooled pistons should allow you to get away with the 1450 (maybe more). It really makes me wonder what kind of testing GM actually did with these trucks - it is as if they are unaware of the temps. And, with GM's proving ground right there in Mesa, you would think they made that run. Get the mice into the pistons with your mods, and they won't even stand behind the motor, even tho a stocker will put out really high temps!

Horse Trainer,


Yes, I was going to Flag. I agree with you that GM had to have made those pulls while testing. I'm sure there are bigger hills out there, but with out desert heat ours are probally the toughest...IMHO.

Some time ago, Hot Rod Magazine did an article on the GM Desert Proving Ground (I think that is its name). In a side bar, they showed a parking lot full of single axle trailers. Not very big - looked like a luggage trailer for an old compact. The trailer has the ability to create a load, and when properly programmed and attached to a vehicle, can be used to simulate different drives without actually having to do them. The just drive around the test track. No accounting for altitude change, winds, being pushed downhill by 16K, etc - all the variables we all encounter every day. Makes me wonder a bit how much might have been missed on our trucks. We really are the beta testers here.

KTDURAMAX, did your fan clutch lock up before you hit 230? GM did a lot of heavy towing for well over a year before the Duramax hit the market. I remember part of an article written back then. It stated they were pulling 12K through Death Valley in 120 degree heat. The Diesel Page guys did a tour all over the Rockies Towing a big trailer and documented their findings. The first summer towing my clutch locked up at 210-215 a couple times and immediately brought the temp down to 195-200. I never saw anything over 200 last summer. The fan engaged a few times last summer but was the result of inter cooler heat. That is usually the signal to slow down a little. Later! Frank

I have had occasions where the fan was engaged, EGTwas 1300+, and coolant temp was barely 200. Maybe we all worry too much about EGT, but I have been around turbocharged engines for close to 30 years, and it has been really drilled into me. Others on the board have run with 1700 EGT - towing. I do wonder if the test vehicles had EGT probes - one would think so, but I have never heard.

My fan clutch did lock up, and only after pulling the last 40 seconds or so to the top of the 4 -5 minute hill did my coolant reach that. I also have just under 5,000 miles so I know my engine is still tight. My temps dropped to 195 very quickly once I crested the hill.........


My fan clutch kicked in all the time pulling at 75 mph....I do think they should have a bigger radiator so that the clutch wouldn't have to engage at all.

I installed my probe in the down tube of the exhaust as there was already a place for it there. Also, my digital monitor instructions adviced putting it there. I do have a 4 inch exhaust. I have seen so many different things about temp when the probe is post turbo and not mounted in the exhaust manifold. What are safe temp readings post turbo? I have never run higher than about 750 degrees pulling a 32' 5er up a long grade at about 70mph. We never get much above sea level here in central US. Thanks, I feel the information from the guys here in this forum is the best available!

I am amazed when I read that some of you have your fan clutch engage occasionally. When I pull my 12k 5th wheel across Missouri, Kansas, and half of Colorado in 90 to 100 degree summer temps, my fan clutch engages off and on all the time. Is this normal and just what I should expect? When I pull La Veta pass headed west out of Walsenberg, CO, the fan clutch almost stays engaged until I hit the crest. BTW, my truck is still completely stock.

It seems like every truck is a bit different, but yours sounds normal. Keep in mind that the fan clutch picks up heat from the following sources: trans cooler, A/C condenser, intercooler and radiator. When pulling La Veta, I'll bet you are running a fair amount of boost, and the heat rejection from the intercooler and the radiator keep the fan engaged.

Over the Memorial Day holiday I pulled my big a$$ trailer from Phoenix thru Globe to Showlow. Trailer with a weeks worth of water/food/stuff and 3 head of horses and feed for them tipped the scales over 15,000. Used the O/D lockout a lot climbing most the mountains and hills. Had to manually shift to 3rd climbing out of Salt River Canyon to keep at the speed limit and keep the EGTs below 1400*. Fan clutch cycling as need. Never saw the water temp above 200* and the transmission never touched 200*. Got home and ordered a 4" flow thru type muffler from one of the advertisers here. I want to lower the EGTs on these runs by 100+ degrees if I can.


BTW, last summer my wife took the trailer to Flagstaff (I disconnected the Juice - just cant trust her!) and she said that on the two long pulls (up to Sunset point and above Maguireville) that she saw 1500* for quite some time! That was in stock setup. Hope GM has studied the pistons and turbo enough because this just seems too damn hot to me.