SI vs CI Engine: Key Differences, Efficiency & Which is Best
SI (Spark Ignition) engines ignite the air-fuel mix with a spark plug; CI (Compression Ignition) engines compress air until it’s hot enough to ignite fuel without a spark. Drivers say “diesel” and “petrol” instead of CI vs SI, so the labels blur. Mechanics hear customers mix them daily, especially when swapping cars or fuel prices…