I'll state it one more time, lol.
My 1250 degree max sustained exhaust gas temperature limit I use when towing is not opinion, or something I used a devining rod to arrive at.....
It is the exact specification given for my engine by International Navistar (the engine manufacturer)
This value was arrived upon based on the ability of the under-piston cooling jets to shed piston dome heat, the ability of the valveguides to shed heat and so on.
More than 1250 and they deem the heat to be a run-away and the engine's expected service life might be compromised.
As to the reason a short burst up to speed will not hurt your engine, it has to do with "Heat soak" for lack of a better term. It just physically takes time to heat up an given component. That's why intermittant temperatures can be much, much higher than steady-state temperatures.
Take a torch with a flame temperature easily hot enough to blow straight through a piston. Now take a pair of pliers and stick the piston in the flame and right back out. Would you honestly expect the piston to have a huge hole in it, lol.
It takes time. And usually long before you've gotten the actual piston dome temperatures high enough to hurt something on an short burst you're going so fast you're out of road anyway.
This is why steady-state towing is the only time egts are not something to mess with.
To put it in perspective, I am actually VERY conservative with my egts compared to nearly anyone making good power with a light diesel.
My 1250 degree max sustained exhaust gas temperature limit I use when towing is not opinion, or something I used a devining rod to arrive at.....
It is the exact specification given for my engine by International Navistar (the engine manufacturer)
This value was arrived upon based on the ability of the under-piston cooling jets to shed piston dome heat, the ability of the valveguides to shed heat and so on.
More than 1250 and they deem the heat to be a run-away and the engine's expected service life might be compromised.
As to the reason a short burst up to speed will not hurt your engine, it has to do with "Heat soak" for lack of a better term. It just physically takes time to heat up an given component. That's why intermittant temperatures can be much, much higher than steady-state temperatures.
Take a torch with a flame temperature easily hot enough to blow straight through a piston. Now take a pair of pliers and stick the piston in the flame and right back out. Would you honestly expect the piston to have a huge hole in it, lol.
It takes time. And usually long before you've gotten the actual piston dome temperatures high enough to hurt something on an short burst you're going so fast you're out of road anyway.
This is why steady-state towing is the only time egts are not something to mess with.
To put it in perspective, I am actually VERY conservative with my egts compared to nearly anyone making good power with a light diesel.