[olddog]

You need to back timing off as boost goes up. If you quit thinking in terms of vacuum advance and manifold pressure (boost) and start thinking in terms of absolute pressure, then it makes more sense. The lower the Manifold Absolute Pressure (MAP) the more timing you need and conversely the higher the MAP the less timing you need.

The way to run boost on a high compression ratio engine is to cool the air back down, to ambient temp, before it goes into the intake manifold. Compression of air heats it. Superchargers compress air. In addition to the heat of compression, inefficiency of the blower adds heat. It the case of the turbo, exhaust heat conducts into the air charge, as well. An after-cooler is the solution.

If the air temp is too high, the fuel/air charge will auto-ignite on the compression stroke before the ignition spark, called pre-detonation. When this occurs, you may not be able to get off the throttle quick enough to save the engine.