Howdy Stang200:
I'm running an honest 9.75:1 in my 250. I'm at 5,000 ft. above sea level here. That's the best trick.
"Tricks" for runing high compression might include; quench band of .030", use dished pistons, polish the combustion chamber, more cam durations for less cylinder pressure, a great cooling system with no more than a 180 thermostat, Cold air intake, a correct Air/fuel mixture, a correct ignition advance system, typically, 2 degrees of additional advance raises octane requirement by 1 so use no more initial advance than you need, make sure you have the strongest ignition system possible with the coldest, good running spark plug, gapped at it's optimal.
Also running gas with ethanal will help some. The alcohol tends to run cooler and cleaner.
The next question has to be why? Unless you have a total combination to use a CR of 9.5:1 or higher at your elevation you're just asking for more expense and head aches. Given your low elevation, summer heat and humidity and desire to run 87 octane gas you would be happier with a ratio of 9:1 and make up the difference in other ways. In theory, all other things being equal, a point of compression is equal to a 4% increase/decrease in hp in a wedge chamber engine. If you have 100 hp at 8.5:1 CR and your raise it to 9.5:1, HP would now be 104, but at higher cost, require finer tuning and have greater heat and stress. CR does make HP, but it has to be part of a total package to be really worth it.
Thanks for being "just curious". That's what makes progress.
Adios, David
