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After searching numerous topics...I've not gottin a decisive value, and if I did it's hard to tell if they're talking pre or post.








So I ask you all this....


What are the guideline for safe EGTs at PRE- AND POST- turbo measures?
 

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I've never seen a decisive # either, just guidelines.


I'm not an envelope pusher... but IIRC, a stock Dmax runs worst case about 1275 degrees or so (Pre Turbo). I hear some power boxes will put you over 1700 degrees (Pre Turbo). Of course the sampled temperature depends on the EGT probe type, and some are more responsive than others.


A good rule of thumb is Post turbo temps are about 300 degrees lower than pre turbo temps. Also, as you would expect, it's not just the temperature but also how long you run the motor at that temperature. And I've yet to hear of any Dmax melting yet.
 

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Well, the typical thermal properties of aluminum alloys lists liquidus melting point at 1180 to 1210 degrees. This, of course, is without the benefits of radiant, gas and liquid cooling that are taking place in the operating engine head. It shows that a precautionary limit of 1275 is pretty reasonable.
 

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The recent Trailer Life mag had an interesting article on towing with a DMAX and a tuner box. It said that the max recommended was 1275 degrees at the exhaust location. They seemed to have gotten the info from GM, based on the way the article is written.


Bob
 

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according to IHI the turbo is designed for continuous operation at 1472 degrees F (800 C)

I've pegged a 1500 degree gauge for 10-12 seconds pulling and dragracing enough times to know the pistons, heads and turbo are NOT melting. But for towing I'd suggest keeping it under 1300 degrees on the long grades.
 

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Son of a gun said:
The recent Trailer Life mag had an interesting article on towing with a DMAX and a tuner box. It said that the max recommended was 1275 degrees at the exhaust location. They seemed to have gotten the info from GM, based on the way the article is written.


Bob

I think "at the exhaust location" must mean at the exhaust port of the head. It sure couldn't be post-turbo or especially down-stream in the system, where tremendous cooling occurs. My Isspro EGT gauge is yellow-lined at 1100 and red-lined at 1275 and my pyro is in the exhaust header about 3 inches from the head.Edited by: Idle_Chatter
 

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mtomac said:
I've pegged a 1500 degree gauge for 10-12 seconds




Read as in excess of 1800°f plus with the combos you are running...
 

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Tom,

They drilled the exhaust manifold in the same place we have seen it done on this site and TDP.

BobEdited by: Son of a gun
 

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I have the standard Juice and tow a big a$$ goose neck trailer out of the Phoenix valley in the summer. Towing on level two I have to keep my eye on the EGTs to keep the long big grades under 1400.


I never let my wife drive unless I back the Juice off to a stock setting. She surprised me the last trip she made to Payson AZ when she got back and told me that she "drove like you do" (meaning foot to the floor) going up the last steep 5 mile grade. The EGTs got to "almost 1500" before she backed off the throttle! (see why I don't let her drive my baby Juiced?)


I have been pretty concerned for some time that the stock configuration might let me get too hot to do damage (before I got the EGT guage), but Chevy can't tell me what is too hot. Naturally, when I drive this beast I want to do the speed limit regardless of what I tow or what the grade is, and for the most part I do, but, even at stock setting when is it too hot for the turbo?


The hot rodders that do the 12-15 second runs are making a shut down at the end of a burst of heat, but for those of us that tow heavy on long grades and reach high temps (1300+) how long before we have a melt down?


Inquiring minds wanna know!
 

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Mitch,

I don't run mine over 1300 degrees. When I get there I back off or shift down.

BobEdited by: Son of a gun
 

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Juice/Attitude set to back down at 1300


Edited by: PULNPWR
 

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We have tested several stock Dmaxs to try and see what the factory was doing and have found that measureing in the exhaust manifold with a fully loaded rig(ie:21,000) we see temps reaching the 1350 deg on long pulls in 110 deg weather. These test have been performed several times with the results always coming in within 25 deg on different trucks. From these tests we donot recommend running higher than 1300 deg as measured pre turbo in the exhaust manifold when towing. If you measure in the exhaust after the turbo within 6 inches from the turbo outlet the max number is 1150 deg.
 

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Diesel Tech


Now finally something that I can hang my hat on! Since I am in the pre turbo configuration I now know when to back off. Does anyone know if the computerized system has a way of telling when the turbo is too hot before it melts down? Like I said earlier, if I had not had an EGT guage, even in the stock settings I have seen this truck run past 1400 climbing out of Phoenix headed to Flagstaff or Payson. I dont want to believe that the general would provide a unit that would melt down for an uniformed owner. (way too spendy for warranty replacements, and I have not heard on this site or TDP of turbo replacements, juiced up or stock)


Once again, thanks for the good information.
 

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Mitchagain said:
Diesel Tech
Does anyone know if the computerized system has a way of telling when the turbo is too hot before it melts down?
Yea, when the turbo melts over the wire harness, the computer shuts down.


I do not believe there is any turbo temp sensor.
 

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There are no sensors to report Turbine heat. GM has preset the calibration to what they feel the max should be. This is why people need to be careful when doing mods. The outside temperature and altitude the engine is being run at have a major affect on EGT's so the same thing that works fine at 40 deg and sea level doesnot work worth a sh*t at 110 deg and 8000 ft. pulling a load!
 

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Diesel Tech - you nailed it on OAT/altitude effect on EGT! Even stock, on a 70 degree day, pulling from Phoenx to Flagstaff can get you way hot in a hurry (1400+). Same type pull in Cal (3000' lower), you are 200-300 degrees lower. Worst part is that too many people are running around without gauges, doing that kind of towing, and thinking they are OK. Then the mice get into the pistons and it is an "owner neglect" issue. Seems like GM could have tied EGT into the ECM and provided that protection.
 

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Like I said, I back off when I get to 1300 degrees. Over the last few years many who seem to know what they are talking about, like DieselTech, keep hitting on the same number.
Bob
 

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My GM engineer budy says "off the record" not to let mine top 1400 degrees. His reasoning is the same as mtomac's.
 

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Mitchagain said:
Diesel Tech


Now finally something that I can hang my hat on! Since I am in the pre turbo configuration I now know when to back off. Does anyone know if the computerized system has a way of telling when the turbo is too hot before it melts down? Like I said earlier, if I had not had an EGT guage, even in the stock settings I have seen this truck run past 1400 climbing out of Phoenix headed to Flagstaff or Payson. I dont want to believe that the general would provide a unit that would melt down for an uniformed owner. (way too spendy for warranty replacements, and I have not heard on this site or TDP of turbo replacements, juiced up or stock)


Once again, thanks for the good information.




I have Blown up a turbo.....Badly, and to add insult to injury, a 'runaway' engine condition after.


Not a pretty site unless you have an extra 4700 to spend on a new unit.
 
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