A warning about Evans Waterless Coolants
I understand that a temperature that is too high or a combustion chamber with hot spots will have issues with preignition. I can understand the theory that fuel vaporization may be enhanced as temperature goes up. So is there such a thing as a theoretical 'approximate' ideal operating temperature for most V8s if hot spots were taken out of the equation?
Short answer: no.
The operating temperature has a lot to do with taking all the variables into consideration. NASCAR engines, for example, are highly refined and have been iteratively improved for decades, so the limits and best areas are well known. But they're also operating in a fairly constant manner. They're also using coolants that are track friendly. Those engines are gulping air the entire time (which is helping shed heat into the intake tract to some degree). Their ideal temperature is likely higher because of that - the intake remains cooler and so the engine heat is bumped up to help fuel vaporization.
Today's OE packages are pushing temperatures up, but they also have to deal with emissions. They have to deal with an owner going from sea level to 11,000ft elevation. They have to deal with -20F mornings and 122F afternoons. They have to deal with idling for 5-15 minutes in stagnant, hot, humid air. They have to deal with air conditioner loads, bad fuel, cheap oils, etc..
The 'best' is the highest you can get away with consistently. But then it has to be backed down for various reasons: hot spots, intended use, traffic, effects on oil viscosity. Effects on longevity of coolants, oils. Then there's the variables like gasoline blends that change, and fuel that is older than other supplies or more contaminated. ~200F seems to work well for most, it's high enough to burn off the stuff that would otherwise condense in our oil, but cool enough not to coke our oil after shut down. It's pretty efficient for fuel burn, but not the best - as always, it's a tradeoff.
