What is the effect of spark timing on the knocking tendency of an SI engine?

Advancing the spark will result in more compression during sparking. The increase in temperature during the sparking will be higher, hence the tendency to knock will increase and by retarding the spark, the tendency to knock will decrease.

What are the causes of knock in a spark ignition engine?

knocking, in an internal-combustion engine, sharp sounds caused by premature combustion of part of the compressed air-fuel mixture in the cylinder. In a properly functioning engine, the charge burns with the flame front progressing smoothly from the point of ignition across the combustion chamber.

Can ignition timing cause knock?

If your ignition timing is over advanced, it means the engine is firing the spark plug too soon. When this happens, the air/fuel mixture ignites too early and causes detonation, which makes the knocking noise you hear. This can be extremely destructive to the engine and should be addressed immediately.

Does advanced ignition timing induces knock?

Advancing the timing causes the cylinder to fire prematurely before it reaches top dead center. Rather than the fuel/air mixture igniting and burning evenly, it explodes sending a shockwave through the engine resulting in “knock”.

What is a spark knock?

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 …

What is advanced ignition timing?

Ignition timing advancing means that the spark plugs are firing earlier in the compression stroke, farther from TDC. The air and fuel mixture in the combustion chamber doesn’t burn right away. Ignition timing advancing might be needed to allow time to get everything ignited.

Why does advanced timing cause detonation?

Aggressive timing advance increases pressure and heat while the mixture is being compressed. This can cause the remaining mixture to detonate.

Which of the following action increases the knocking tendency in SI engine?

Low inlet pressure and temperature reduce knocking tendency in SI engines but increase the knocking tendency in CI engines.