In this video, Bob Morreale explains engine knock—what it is, why it’s harmful, and what causes it. Engine knock occurs when combustion happens prematurely during the piston’s upward movement in the cylinder, causing shock waves that the piston has to fight against. This is often due to excessive spark advance or an improper air-fuel mixture. Knock produces a distinctive pinging sound similar to metal tapping or glass scratching. Tuners play a critical role in preventing knock by ensuring correct timing and proper air-fuel ratios, but other factors such as boost pressure from turbochargers, fuel quality, and varying octane ratings also contribute. He emphasizes that lower-quality fuels, including winter blends, can increase knock risks. To mitigate these issues, using fuel additives or “boosting shots” can help raise fuel octane and resist premature ignition. Overall, careful tuning and fuel management are essential to avoid knock, protecting engine performance and longevity.

Highlights

🔧 Engine knock occurs when combustion ignites prematurely in the cylinder.

🔥 Excessive spark advance is a common tuning error causing knock.

⛽ Fuel quality and octane rating directly affect knock susceptibility.

🚗 Turbo boost levels must match fuel octane to prevent knocking.

🔊 Knock sound resembles pinging or metal tapping.

💡 Fuel additives can help increase octane and reduce knock.

🛠 Tuners must balance air-fuel ratio and ignition timing to avoid knock damage.