What happens during pre-ignition and detonation?

Both pre-ignition and detonation put tremendous mechanical stress on the engine, and transfer a great deal of heat into the piston deck. This can scour the protective layer of insulating air that separates the hot gasses from the aluminum piston surface causing the piston to melt (EGT is 1600 degrees.

How do I stop pre-ignition?

Pre-ignition is combustion inside the cylinder BEFORE the spark plug fires….The best way to prevent pre-ignition is to:

  1. Ensure the cooling system is adequate and well maintained.
  2. Use spark plugs with the correct Heat Range for your application.
  3. Properly Install Your Spark Plugs.

What is pinging and detonation?

Knocking (also knock, detonation, spark knock, pinging or pinking) in spark ignition internal combustion engines occurs when combustion of some of the air/fuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug, but one or more pockets of air/fuel mixture explode …

How does pre-ignition lead to detonation and vice versa?

Pre-ignition is initiated by an ignition source other than the spark, such as hot spots in the combustion chamber, a spark plug that runs too hot for the application, or carbonaceous deposits in the combustion chamber heated to incandescence by previous engine combustion events.

How do you determine Preignition?

An oscilloscope is used to identify preignition; detonation is determined by its audible knock. With increase in compression ratios and power output necessitating study of these phenomena, it is expected that proper instrumentation for differentiating between the two will be extremely useful.

What is the difference between knocking and detonation in SI and CI engine?

Knocking vs Detonation Knocking is the making sharp sounds due to uneven combustion of fuel in the cylinder of a vehicle engine. Detonation is the process of pre-ignition or auto-ignition of a fuel in an engine’s combustion chamber.

What are the effect of detonation?

when detonation occurs, the fuel charge ignites quickly in an uncontrolled explosion, causing a pounding or hammering force on the piston rather than a steady push. Moderate to severe detonation could be noticed as engine roughness, vibration or loss of power and eventually engine damage.

What is the difference between detonation and knocking?

In general, detonation is the cause and knocking is the after effect. Those who deal the terms knocking and detonation as a separate phenomenon, do so by referring auto-ignition theory as knocking and detonation theory as detonation.

How do you calculate detonation?

The velocity of the shock wave at the explosive/air interface is determined from the high-speed camera images and the detonation velocity is ascertained using Rankine-Hugoniot jump equations. The result is compared to published values for the explosive being tested.