Exhaust Temp Limit

[Mauseth]

With my 2006 I am pulling a 36' 5th wheel trailer weighing about 17,000 lbs. loaded. When towing in the mountains what is my limit on the exhaust temps? I have read that 1350 is the temp aluminum melts, and I have read that the new trucks can run a higher exhaust temp. I also read on another site that 1450 can be run for a period of time, but not an excessive length. I am asking those on this site for their advice and recommendations.

 

[bigceltic]

Here is a thread I found informative when I was trying to find the same info: https://www.turbodieselregister.com/threads/248458-Egt-help?highlight=max+egts From what I have come to understand, the temps that the engine can sustain (EGTs) are really based on whether running bone stock or adding extra fueling via a programmer.

Hope this helps.

George

 

[The patriot]

I'd like to add, it really depends on how long you want your truck to last.
Do you get a new truck every 3-4 years?
I'm the original owner of my 1998, and I have no plans on selling her.
People like me would error on the low side.
jm.02

 

[cerberusiam]

The problem is not what EGT's are too high, rather how long they are there to heat soak the piston. Aluminum may melt at 1350 but your pistons are cast aluminum blend, they have a much higher melting point plus they are oil gallery cooled. EGT's read at the manifold do not reflect cylinder temps, under a hard pull in-cylinder temps in the hot part of the combustion can exceed 5000 degrees. What matters is how much heat the piston absorbs and that has a multitude of variables.

Stock trucks will run 1450 degrees constant and given everything is good won't have issues, hard to make that happen but that is what Cummins will allude to. Adding fuel, changing timing, duration or pressure and toss that out the window. Under the right conditions you can melt a piston at less than 1200 degrees EGT's, or, you can run 1400+ for hours with no ill effects. No hard and fast rule for what is a good or bad EGT number.

You list an EJ/A in your sig, be VERY careful with extended EGT's at or above 1200 degrees with the tuner. That tuner runs a lot hotter in-cylinder than others and it will eat things if you are not careful. Constant will under 1200 degrees and limit the 1200+ to 30 seconds or less and you will probably be fine.

 

[AH64ID]

As it has been mentioned the tuning plays a big role.

The E J/A is known to run HOT or HOTTER!!!

A Stock 2006 will sustain 1450° in the manifold with cooler cylinder temps than a properly tuned 2006 with 1250° EGT's.

 

[Tuesdak]

"I have read that 1350 is the temp aluminum melts"

This is a useless urban legend. :-laf

As mentioned above the peak combustion temperature is way hotter than the EGT reading. What is useful to remember is a diesel's high compression heats the air enough to light diesel when sprayed in the cylinder, but, on the power stroke the heated air is allowed to expand. This expansion cools the gas for the same reason air out of your blow gun or air tool is cold. The cooling is so great that even after burning the main event post injection events for DPF cleaning doesn't burn in the cylinder - it burns in the cat!

Advance that keeps the heat in the cylinder longer, ECT, oil temp, load, IAT at the intake valve, exhaust back pressure, EGR, are some of the variables that control what EGT your engine can take at a given moment.

For example more advance will reduce turbo spool, reduce EGT's, but, has higher NOx meaning higher in cylinder temperatures and longer heat exposure to the parts you don't want to melt. Retarding the timing will raise EGT's and spool a turbo quicker. (This is useful for spooling large turbo's in a custom tune. Advance to generate power when the engine RPM is too low to spool the big turbo, retard the timing at the RPM and throttle the turbo will spool at causing EGT's to spike and light the turbo, and then advance after that RPM to take advantage of the turbo.)

The melting point of aluminum is as useless of a number as the melting point of cast iron manifolds that are glowing hot. I would be concerned about header wrap and turbo blankets that appear to seriously scorch at a sustained 1550 EGT as I did in another ride. Yeah burned black underside of a turbo blanket... EGT only gave me heartburn, but, engine oil failure and piston scuffing pushing that hard IS a concern.

YMMV as each engine design is different let alone each engine. Pistons are not the only things to worry about as I understand valve seats dropping are a concern on some years of Cummins engines.

 

[NIsaacs]

I have read that 1350 is the temp aluminum melts,.

It is rare for a piston to melt unless you have a bad injector. What happens is too much heat will swell the piston faster than the cylinder walls (they are surrounded by coolant) then the piston will make contact with the cylinder, instant scoring. The more miles you have on the truck the more clearance you have and the more fuel you can get away with.

Nick

 

[AH64ID]

It is rare for a piston to melt unless you have a bad injector. What happens is too much heat will swell the piston faster than the cylinder walls (they are surrounded by coolant) then the piston will make contact with the cylinder, instant scoring. The more miles you have on the truck the more clearance you have and the more fuel you can get away with.

Nick

Generally very true, aside from the crappy piston design used in 2004.5-2007. The late HPCR pistons are the easiest to melt piston in the Dodge/Cummins history. Talking to several shops/builders the most common failure for the late HPCR is piston issues on stock and aftermarket tuning alike.

 

[p-Bar]

So what do you use for pistons if you were rebuilding?

 

[AH64ID]

So what do you use for pistons if you were rebuilding?

03/04 or the QSB 480 piston. They are both 100% compatible with an injector nozzle change.