[comptiger5000]

You're better off keeping the higher temp t-stat and cooler fuel to avoid vapor lock. Try warming the fuel, but not enough to vapor lock it.

You're missing the point here. Dropping the engine temp only increases the ping threshold a little. Hotter/cooler air and fuel have a much greater effect. Ideal for high compression is reverse cooling flow (heads first, then cylinder walls), a 180* or 195* t-stat, and cold air coming in. For FE, the same equation with warm air would be good (although not as high compression). Running the engine too cold is counter-productive, and also increases wear.