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Discussion Starter · #1 · (Edited)
Having a discussion at work today about wether high egt's will kill pistons or the turbo first.

I have always heard that you want to keep the egt's down below the melting point of aluminum to avoid the pistons going :nuke:

My co-worker says the turbo is at more risk during high egt's.

Regardless, I think it is application specific. He found this quote from banks to back up his claim:

We’ve already mentioned that excessive EGT can cause engine damage or turbocharger damage, but let’s get more specific. Which parts will fail first is a matter of the design and materials used in the various parts of the turbo-diesel, but usually it starts with the turbocharger. Under sustained excessive EGT, the square corners at the outer ends of the vanes, where the material is thinnest on the turbine wheel, can become incandescent and then melt, resulting in a rounding off of the square corners. If you or your mechanic finds this indication before anything more serious happens, consider yourself very lucky, because shortly after the tips melt, the turbine wheel goes out of balance and wipes out the turbocharger bearings, which may or may not result in shaft failure and destruction of the turbine and compressor wheels. Excessive EGT can also erode or crack the turbine housing. In extreme cases, high EGT can drive the turbocharger into an overspeed condition that exceeds the designed operating speed due to the additional heat energy. When this happens, either the turbine wheel or the compressor wheel may
burst.


Any thoughts?

Oh and the vehicle in question is a 1975 Diamond Reo log truck with a 350 horse cummins.
 

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On the ol' Reo, the turbo would be first, on anything with Aluminum pistons, they'll go first.
If you think a turbo having a high-speed come apart is cool, you should see what happens when you melt the pistons!!! I melted a 6.2 into oblivion.
 
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