Jim:
**I believe that the ROP has excess fuel which should cool the burn and just maybe leave MORE lead on the valve stem than while LOP.**
1) The excess fuel really does not cool the burn. What happens is that the excess fuel delays the burn RATE, which delays the peak pressure, which lowers the pressure against the thermal boundary layer and decreases the number of BTUs that are transferred into the metal.
2) I garner from your statement that you think lead in the fuel helps lubricate the valves. This is another OWT. Lead as it exists during and after the combustion event is a salt of bromide. (Bromide is added to the fuel to scavenge the lead so it leaves the combustion chamber, rather than leave deposits. Since the temp of combustion is around 3800 dF and the lead salt melts at 1308dF, it leaves the combustion chamber as a gas.) In any case, salts are abrasive. Abrasives make really poor lubricants. Lead does nothing to lubricate the valves. Nothing.
Walter
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