Where should the desired maximum cylinder pressure ideally occur in relation to crankshaft position?

The desired maximum cylinder pressure should ideally occur 10-15 degrees After Top Dead Center (ATDC) during the power stroke. This is because, at this point in the crankshaft's rotation, the combustion process has mostly completed, and the pressure from gases produced during combustion is at its peak, effectively transferring power to the crankshaft.

When the piston reaches Top Dead Center (TDC), the combustion gases exert their maximum pressure as the fuel-air mixture ignites. However, to ensure efficient energy transfer and to accommodate for the moment when the piston has started its downward movement, it is optimal to reach peak cylinder pressure just after TDC. This timing allows for the piston to utilize the expanding gases effectively, maximizing torque and power output without risking knocking or misfires which could occur if pressure were to peak too early.

Understanding this timing helps in optimizing engine performance, fuel economy, and overall efficiency, which are critical factors in engine design and tuning.