Robert, you don't want to maximize pressure in the chamber. You want to apply the most pressure where it does the most good. With the crank arm at or near TDC, pressure in the cylinder is nearly useless. When the crank arm is 90d ATDC, pressure in the cylinder does the most work. Ideally you'd create pressure quickly as the piston approaches 90 deg ATDC. But with cylinder volume increasing (at an increasing rate), this is tough to do. The best method would use a high octane, fast burning fuel and start ignition ATDC to allow maximum compression ratio while resisting detonation and eliminating negative work.

I'd love to see the timing curve on one of Smokey's hot vapor engines.