https://www.hotrod.com/articles/ignition-timing-free-hp-heres-get/ >It's generally acknowledged that peak cylinder pressure needs to occur at roughly 15-18 degrees After Top Dead Center in order to maximize leverage on the crankshaft. http://www.contactmagazine.com/Issue54/EngineBasics.html >There is another factor that engineers look for to quantify combustion. It is called "location of peak pressure (LPP)." It is measured by an in-cylinder pressure transducer. Ideally, the LPP should occur at 14 degrees after top dead center. Depending on the chamber design and the burn rate, if one would initiate the spark at its optimum timing (20 degrees BTDC, for example) the burn would progress through the chamber and reach LPP, or peak pressure at 14 degrees after top dead center. LPP is a mechanical factor just as an engine is a mechanical device. The piston can only go up and down so fast. If you peak the pressure too soon or too late in the cycle, you won't have optimum work. Therefore, LPP is always 14 degrees ATDC for any engine. https://www.comeanddriveit.com/engine/detonation-and-knock >Ideally, you want peak cylinder pressure to occur between 14 18° ATDC to maximize the mechanical leverage of the rod and crank positions.