(inspired by another thread)
In the 70s and 80s during the phase-out of tetra-ethyl lead in gasoline, hardened valve seats were installed to prevent damage and wear due to the absence of the protecting lead.
Diesel engines NEVER had lead, so how did valve seat wear not be a problem?
Did diesels ALWAYS have hardened valve seats?
bump
Perhaps the combustion temperatures are lower, and valve-burning was not an issue? I dunno.
The brief answer is:
Diesels were already “hardened” from the git-go.
Long answer:
Because diesels were “industrial” engines, they were built to be heavy-duty, longer-life engines. Since diesel burns from the heat of compression, the entire engine had to be stucturally stronger than a gasoline engine.
As far as fuel temperature, it’s true that diesel burns “cooler” than gasoline - actually, gasoline burns really hot in one place (the point of ignition) for a short time period, and diesel burns “longer” in the chamber.
Diesel engines also have a much lower average RPM than comparable gasoline engines, and a smaller RPM range. For example, automotive diesel engines top out around 3500-4k RPM, whereas your gas engine can go 5.5k and up…Fewer RPM’s=fewer times the valves seat…
Hope that helps some…
Diesel is also a lubricant - iirc, the lead in gas functioned as a valve-train lube, which diesel would do on its own.