The maximum horsepower figures of most car engines have been high for many decades.How long would an engine last on the dyno when making max HP ? How would this expected life drop when aftermarket performance mods are added? Would large old V8 motors like stock chev 350 be better in this respect? When I would see Vintage petrol engines used in generator sets the max cont KW output of the generater was more than half of the BHP of the engine . These old gensets were setup to make 50Hz running at a governed 3000rpm.The old engines that I have seen ,are Flathead ford V8.Coventry climax in line 4,Austin 36HP OHV inline 4.Would modern car engines have to be derated for such service?

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    There is no way to answer these questions. Every engine is going to be different. There is no way to put an "x" value to how long an engine is going to run or keep running. Even engines which are built the same aren't going to survive the same amount of time or stress. Consider re-asking your question in a more subjective manner. Remember, while most engines have a redline, they aren't designed to live at that redline. Feb 14, 2016 at 13:39
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    Generators with gas operated engines do not need to cycle through an RPM range and are set up in its most efficient running condition. Other factors would be that the flat heads allow for more compact space heighthwise and allow for quicker servicing. Not necessarily the most efficient method of airing and fueling an engine, but the best trade off with end item design constraints.
    – Tobin S
    Feb 16, 2016 at 16:27
  • Way too broad. Some engines have max continuous RPM limits (like my 5S-FE) that are below the redline, but that's more of an engineering courtesy than any kind of guarantee. Feb 16, 2016 at 17:12
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    The question is valid. A good example is aircraft engines, which spend 90% of their lives at 70 to 80% of their rated capacity.
    – mongo
    Apr 29, 2021 at 20:17


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