I just bought an EGT gauge and i was just wondering, at what temp should i start to worry about any problems happening, like if i have really been romping on it and riding it high rpms.

 

Aluminum melts just under 1250* Farenheit. Your pistons are made of aluminum. Along with a few other things in your turbo.

 

The pistons will never see that temp though. Combustion temps are ~2000-3000 degrees, but the hard parts of the motor are adequately cooled, including the pistons, so they survive. The turbo can also take much more temp than diesels run EGT at. Turbo gasoline engines run EGTs up to 1600-1800 degrees for entire drag runs.

The general consensus with diesels is to keep EGTs to 1300 at most, but it's just coincidence that aluminum melts around that same temp.

 

Please expand on that some. UR not implying that a diesel cant make high EGT's r ya?

Short bursts of 1250+ isnt going to hurt anything, no. As u have to get the aluminum that hot first before it melts, but it isnt just about the aluminum either, it the bearings a oil ya gotta worry about too, when u run high temps.

Welcome to DTR by the way!

 

I think he's just saying that compared to a gas engine, diesel's really don't make very high EGT's. Like he said, turbo gas engines run much higher exhaust temps.

Garrett5462, if your timing is stock, Cummins says not to run over 1250* continuously.

 

Is 1600* hot enough? I pegged the meter pulling the boat on level ground with my old injectors and can do it with the ones I have now. Dieseldude4X4 has a melted piston on his desk that was removed from his CDT after pulling a trailer up along grade without an EGT meter outside Charlottesville VA. They don't let go right away, but they will let go. KEep it below 1300.

 

I'm sure diesels can make as much EGT as you want. What I was saying is that the turbo can take a lot of temperature, more than even gas turbo motors make in normal operation. Consider road racing applications where you can be at or close to full throttle 50-75% of the time for 30-60 minute laping sessions. This was in response to a post above where it was therein implied that the turbo is going to melt at over 1250C.

Of course it must also be mentioned that the other factor that determines how much heat a component can withstand is time... Nothing can take high heat for excessive lengths of time.

 

U are right, it takes time, but not much to waste them componants that are aluminum. The acctual melting point of aluminum is something like 1222.2* F, not really 1250. But still, 1200* is awfully hot by any standards, any turbo manufacturer, rebulider, performance specialist, is going to tell you 1250* max sustained degree's pre-turbo is it.
But hey, I never had EGT issues either, so Im not going to tell you that at 1251* I had a melt down. The highest I EVER saw was 1300* for about 2 seconds cause I had to get out of it for other reasons

Anyway, point is, yes 1250 is ok in short bursts, (a fews seconds) but not for any longer then that.
Im sure them road racers r using intercoolers, no one is going to keep sustained temps over aluminum's melting point for long.
Im really not trying to argue, but thats just the simple fact of it, u will melt pistons, and the turbo over 1250* F.

 

We run pretty large intercoolers on the turbo 4 bangers, 24x12x3.5 at the least, and still see 1600 plus for sustained periods. We also run much less robust engine internals, and very similar turbos. Sometimes the same, people are adapting HX35s and 40s to Eclipses and Talons.

My point from the very beginning is that EGTs may be 1600 degrees, combustion temps may be 2500 degrees, but the temp of the actual parts is nowhere near that! Pistons for example are cooled through contact with the cylinder walls, oil sprayed on the underside, cool (relatively) intake charge, conduction through the rings, etc. Turbos are cooled by oil or oil and water, compressor flow, etc.

EGT over 1300 degrees does not mean the aluminum parts are over 1300 degrees. It's an extremely common misconception that will be eternally perpetuated by the intarnet. The fact that it is commonly advised that EGTs do not exceed 1300 degrees (diesel only! Gas recomendation is much higher, 1600-1650) and aluminum melts at 1250 degrees is purely coincidental! Perhaps I should have worded it this way from the start.

I too am not trying to argue, this is a great forum and a great group of guys! While diesel performance is a small side hobby of mine, building and tuning 500-600 wheel horsepower 2 liter 4 cylinders is where I spend the majority of my free time. While there are some distinct tuning/engine management differences, all of the same physics still apply. I really do hope to be able to contribute to this forum occassionally when these similarities arise. In the meantime, I will continue to enjoy the wealth of information that exists here.