432 Q12 Performance

We trigger the spark (SIEs) or fuel injection (CIEs) before TDC, not exactly at it, because

• it takes time to break the reactants molecules and start combustion.
• combustion must start before TDC.
• combustion must start at low pressure.
• the exhaust valve opens at TDC.

With optimum spark / fuel-injection timing,

• the cylinder peak p & T occur almost at TDC.
• the engine has lowest friction power.
• the engine has highest volumetric efficiency.
• the engine has higher compression ratio.

We have freedom to change the duration of ignition delay arbitrarily (كيفما نشاء).

• True.
• False.

Spark (in SIEs) and fuel injection (in CIEs) can be triggered at any time within the compression stroke.

• True.
• False.

While optimizing the timing of spark (SIEs) or fuel injection (CIEs), we should always retard them for better performance.

• True.
• False.

The peak cylinder p & T increase linearly with rpm.

• True.
• False.