High-performance engines are designed with higher compression ratios or use forced induction to pack more air into the cylinder, significantly increasing this pressure and heat.
An engine designed for high output must use 93 octane fuel because the fuel’s increased stability prevents it from igniting too soon under these extreme conditions.
Modern vehicles are equipped with sophisticated knock sensors that constantly listen for the vibrations caused by detonation. When a sensor detects this abnormal combustion, it sends a signal to the engine control unit (ECU). The ECU’s immediate response is to “retard” the ignition timing, which means delaying the spark plug firing until a safer point in the piston’s cycle.
This timing adjustment successfully protects the engine from damage, but it also reduces the engine’s efficiency and power output. Using 87 octane in an engine that requires 93 forces the ECU to permanently run a less aggressive, less powerful timing map to prevent constant knock. The engine will technically run, but it will not achieve the performance and fuel economy it was engineered for.