Mechanical Engineering - IC Engines and Nuclear Power Plants - Discussion

Concept of Specific heat is used when describing the capacity for heat absorption. Specific heat is the amount of heat energy (joules) per unit mass (grams) required to raise the temperature of a substance by one degree Celsius.

The greater the specific heat, the more energy a substance absorbs before it heats up. Gasoline has a specific heat value of 2.02 joule/gram-°C. Water has a specific heat of 4.18 joule/gram-°C.

This means, for an equivalent volume, liquid water will absorb about twice as much heat as gasoline while increasing in temperature the same amount. So for inhibiting pre ignition water is preferred.

"lead" was used in early model cars to help reduce engine knocking, boost octane ratings, and help with wear and tear on valve seats within the motor. Due to concerns over air pollution and health risks, this type of gas was slowly phased out starting in the late 1970s and banned altogether in all on-road vehicles in the U.S. In 1995. Lead the effective inhibitor of pre-ignition.

Concept here may be Cooling water jacket outside that would surely reduce pre-ignition & knocking tendencies.

Lead used as anti knocking agent.