I have a question for those of you with more experience under their belt than I. If we say that 1250 is the safe egt limit why is it that under racing conditions some people talk about 1300-1500 deg exhaust temps??
EGT Thoughts
- Thread starter dsltech83
- Start date
Diesel JD
Full Access Member
Maybe because it's for a short duration and under racing conditions the idea of obliterating an engine isn't intolerable it's part of the game? All pistons are aluminum as far as I know, except for custom made ones, so it can't be different materials...or at least not THAT different.
2stroke
Full Access Member
Pistons are mostly the same depending on aluminum aloy but ceramic coatings make a big difference, even the coating used on the factory 7.3 turbo makes a difference
Yes aluminum does melt at 1250f I guess oil cooling it makes a difference at this temps. It is true many run up to 1600f and more but they do it for short time and if You do this all the time You will shorten the life of the engine as opposed to run it always under 1250f.
Anyone who likes to hammer the go pedal and keep going even when the gauge marks past the 'safe' line sooner than later finds the breaking point of their engine.
Anyone who likes to hammer the go pedal and keep going even when the gauge marks past the 'safe' line sooner than later finds the breaking point of their engine.
Black dawg
Registered User
I know a guy with a turned up dodge that for years had no pyro. after the pyro was put in he saw that pulling the pass, was tough to keep it under 1300, and most of the time was 1600. was run that way with the same load for 5 or so years run hard.
crashnzuk
Full Access Member
I was reading some Hypermax stuff yesterday and they said 1350 was the typical max sustained to stay at or below. Pistons are not pure aluminum, so I bet the actual melting point is WAY higher than you might think. Even then, running real hot isn't gonna help you in the long run.
Travis..
Travis..
icanfixall
Official GMM hand model
Pistons are an alloy of differant materials that help it wear longer at high temps and piston to cylinder scuffing. When they get close to melting they will distort first. Sometimes the piston crushes the wrist pin. Other times the top of the piston melts down and sticks the top ring. Also at what temp is your engine really running... Maybe a pyro isn't telling you the true temp. Some can be off by 100 degrees.... I'm not willing to find out what temp my engine melts at... I generally run no hotter that 1050 degrees and I sleep just fine at nite.....
Who are these people?
If your talking about NASCAR, Modified or Drag it's comparing apples to oranges. There built to run 9000 RPM. Doubtful if any of them have a pyro gage in them.
Production engines are not built to stand rigorous abuse for long periods of time, that's why it's common for most folks to adhere to the 1250 F "rule"
As others have said, ceramic coatings will help a great deal, and between piston oil cooling jets and various alloys, you can PROBABLY push EGT's a bit beyond 1250 for a short period of time without damaging anything. However, I've said before and I'll say again that in my VERY strong opinion, doing so is playing with fire...you might get away with it once or twice or maybe even more often, but that doesn't mean the pistons will remain as strong as they would otherwise have been, and CERTAINLY does not mean you aren't potentially risking catastrophic damage.
I've told this story before, but it bears repeating...my first diesel was a 1980 IH Scout with the cute lil' Nissan SD-33T turbo. A previous owner had installed a pyro and a boost gauge...and, one day shortly after buying it, I tried to climb a rather steep hill with it while towing a Chrysler LeBaron. I hadn't had a chance to learn all the intricacies of the engine, and while I had had experience with diesels, it was almost exclusively 2 stroke Detroits in marine applications, and I hadn't learned the importance of watching the pyro nor what the implications were. So, when I was trying to get up this hill with the pedal to the floor in 2nd gear and watching the pyro get up past 1300 F, I didn't think it was a big concern. When I got home that night, I decided to look it up...and was horrified to learn that a) the maximums were 1250 F for a pre-turbo mount and 1000 F for a post-turbo mount, and b) that my pyro thermocouple was mounted post-turbo
The engine ran okay, and I thought I had dodged a bullet...but, after about 6 months (during which I was very careful with the engine, having learned better), I started to notice a slight puffing from the road draft tube....and, over the course of the next year, the puffing got worse to the point where I was leaving a huge cloud of smoke and even got pulled over twice. I never did a post-mortem on the engine (the body was too badly rusted out; I sold it to a guy in Oregon who parted it out), but the best me and the Scout message forum I was a part of at the time could determine, that one overheat weakened either a piston or a ring bad enough that normal operation kept eating away at it until it finally cracked.
Moral of the story: Hot-******* aside, the recommended limits are there for a reason...feel free to disregard them if you so wish, but do so at your own risk and don't blame the engine when it fails. OTOH, from an engineering perspective (if not a political perspective
), I tend to be very conservative...I've been left stranded on the side of the road too many times for my liking (which is why I go out of my way to avoid owning anything powered by gasoline 
), so I'd rather err on the side of longevity than go hot-******* around and risk calling a towtruck at an inopportune time.
Why do I have the sickening suspicion that a certain someone on here's now going to make a point of pushing his EGT's as high as possible and proclaiming success after one or two runs before his engine blows up?
I've told this story before, but it bears repeating...my first diesel was a 1980 IH Scout with the cute lil' Nissan SD-33T turbo. A previous owner had installed a pyro and a boost gauge...and, one day shortly after buying it, I tried to climb a rather steep hill with it while towing a Chrysler LeBaron. I hadn't had a chance to learn all the intricacies of the engine, and while I had had experience with diesels, it was almost exclusively 2 stroke Detroits in marine applications, and I hadn't learned the importance of watching the pyro nor what the implications were. So, when I was trying to get up this hill with the pedal to the floor in 2nd gear and watching the pyro get up past 1300 F, I didn't think it was a big concern. When I got home that night, I decided to look it up...and was horrified to learn that a) the maximums were 1250 F for a pre-turbo mount and 1000 F for a post-turbo mount, and b) that my pyro thermocouple was mounted post-turbo
The engine ran okay, and I thought I had dodged a bullet...but, after about 6 months (during which I was very careful with the engine, having learned better), I started to notice a slight puffing from the road draft tube....and, over the course of the next year, the puffing got worse to the point where I was leaving a huge cloud of smoke and even got pulled over twice. I never did a post-mortem on the engine (the body was too badly rusted out; I sold it to a guy in Oregon who parted it out), but the best me and the Scout message forum I was a part of at the time could determine, that one overheat weakened either a piston or a ring bad enough that normal operation kept eating away at it until it finally cracked.Moral of the story: Hot-******* aside, the recommended limits are there for a reason...feel free to disregard them if you so wish, but do so at your own risk and don't blame the engine when it fails. OTOH, from an engineering perspective (if not a political perspective
), I tend to be very conservative...I've been left stranded on the side of the road too many times for my liking (which is why I go out of my way to avoid owning anything powered by gasoline ), so I'd rather err on the side of longevity than go hot-******* around and risk calling a towtruck at an inopportune time.Why do I have the sickening suspicion that a certain someone on here's now going to make a point of pushing his EGT's as high as possible and proclaiming success after one or two runs before his engine blows up?
pacaman
Registered User
The real number
I have seen and talked to a number of IDI owners that have EGT gauges and what I think is that everyone has a little different set up so how real are the numbers we talk about. The placement of the probe (manifold, up-pipe, etc.), the type of the probe (mechanical vs electronic) and the response time not to mention the different technologies in the gauges.
When I was looking for a guage I was not impressed with the standard automotive gauges so I installed an industrial digital gauge and type k t-couple. With the setup I have the response time is almost instantious, I can hit 1350 at 3k in second gear without a load if I'm not careful. I have a moose pump and that has made it even faster. My point is that I have seen others that run just a hard and their egt gauge dosen't catch-up and by the time it does the engine has already changed rpm so they never see the numbers that I do.
Just my 2 cents!
I have seen and talked to a number of IDI owners that have EGT gauges and what I think is that everyone has a little different set up so how real are the numbers we talk about. The placement of the probe (manifold, up-pipe, etc.), the type of the probe (mechanical vs electronic) and the response time not to mention the different technologies in the gauges.
When I was looking for a guage I was not impressed with the standard automotive gauges so I installed an industrial digital gauge and type k t-couple. With the setup I have the response time is almost instantious, I can hit 1350 at 3k in second gear without a load if I'm not careful. I have a moose pump and that has made it even faster. My point is that I have seen others that run just a hard and their egt gauge dosen't catch-up and by the time it does the engine has already changed rpm so they never see the numbers that I do.
Just my 2 cents!
The Warden;510777Why do I have the sickening suspicion that a certain someone on here's now going to make a point of pushing his EGT's as high as possible and proclaiming success after one or two runs before his engine blows up? :shocked: :rolleyes:[/QUOTE said:
dyoung14
Is getting worn out
Wish i had my egt gauge in the other night, when i passed 25psi with a thick cloud of black smoke
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