Using 91-octane premium fuel instead of 87-octane regular fuel will only increase your engine's power if your car's manufacturer specifically designed the engine to require it.
Higher octane fuel resists knocking or 'pinging' under compression, which is a premature ignition of the fuel-air mixture. Engines designed for higher octane can take advantage of this resistance to operate at higher compression ratios or with more advanced timing, which can lead to increased horsepower and efficiency. However, if your vehicle's owner's manual specifies regular 87-octane fuel, using premium 91-octane will likely offer no discernible performance benefit and is generally not recommended. Always consult your vehicle's manual for the correct fuel grade.
Fuel octane requirements are determined by the vehicle manufacturer and using a higher octane than recommended typically provides no benefit.
What is the difference between 87 and 91 octane gasoline?
The primary difference between 87 and 91 octane gasoline lies in their resistance to premature detonation, commonly known as engine knock or pinging. Octane rating is a measure of this resistance; a higher octane number indicates greater resistance. Regular gasoline typically has an octane rating of 87, while premium gasoline is usually 91 or 93. Engines designed for higher octane can operate under higher compression or with more advanced ignition timing without knocking, potentially leading to better performance or efficiency. If your car is designed for 87 octane, using 91 will not provide additional power.