Normal 87 Octane vs. Premium 91 Octane. Which petrol?
Since the time premium fuels have entered the market, Consumers have had to deal with more than just confusion and misconceptions. Some said, low octane gives same performance as high octane while some said high octane gives you more power and mileage.
So, what needs to go in your car? In one word, 87 Octane if you drive from home to office in a regular car.
That's not to say that 91 Octane doesn't serve its purpose.
At the time of writing this article, fuel prices in India have reduced by 90 paise. The current prices stand as mentioned below.
87 Octane - INR 72.16 per liter ( 4.92 USD per gallon)
91 Octane - INR 81.57 per liter ( 5.59 USD per gallon)
Even if you are sure premium fuel helps in increasing the efficiency, it has to be atleast 15% more to justify the higher fuel price. But here are some facts you need to know.
1. Read the manual: Cars and bikes today are compatible to a variety of fuels. To cater to various engines gas companies have also taken the extra step and now we have fuels ranging from E85( Ethanol) to regular 87 Octane all the way till 97 Octane. Yes, it's true that some high-end cars like Ferrari and Bentley's run only on 97 Octane but running your cars on such fuels will not make your cars go faster; your wallets might be lighter though. Ferrari's and Bentleys can run on normal petrol too if the company programs the ecu's to let them. All it will do is reduce the Horsepower numbers which they so bravely boast.
When in doubt stick to the manual. The manual on my Mitsubishi Lancer suggests atleast 87 Octane while the manual for Honda Fit/ Jazz and Royal Enfield Suggest to use 91 Octane petrol or higher. If you are not sure what to use, stick to what is recommended. I fill premium petrol when any of my car is to go through heavy stress (extreme stop and go traffic for 10+ kms or hill climbs).
PS: Most Premium fuels are just regular fuels mixed with Octane boosters. You can fill regular fuel and go for Octane boosters for much lesser money.
2. Your ECU knows: Almost all new cars of today have emission sensors fitted. These sensors have the ability to detect what petrol is being used and tune the engine accordingly. So irrespective of which fuel you use, your car will make the best use of that fuel. If it is 87 Octane the car will lower the compression and if the fuel is 91, it will burn the fuel completely.
PS: Higher Octane count doesn't mean the petrol has more energy, in fact higher Octane has less energy than 87 Octane.
3. Compression Ratio : The ratio of the volume of its combustion chamber from its largest capacity to its smallest capacity is called compression ratio. The higher the ratio, the more it makes sense to use a premium fuel and lower the ratio, better it is to use normal fuel. In such a case if normal fuel is used in a high compression engine, the engine is susceptible to engine knocking. So the next time your engine knocks, check for the fuel used.
4. Engine type: Naturally aspirated small capacity engines used by people everywhere are not able to make efficient use of Premium fuels. The benefits from using premium fuels in such cars will draw minor benefits. On the other hand big engines/ turbocharged cars will make better use of premium fuels. Hence a Ferrari will run better on a 97 Octane while our small engined Tata cars will run better on 87 octane.
5. Driving Style: Our driving styles affect the petrol usage a lot. The amount of fuel as per requirement from the gas pedal is sprayed into the engine via a Fuel Pressure regulator. When the gas pedal is pressed more, more fuel is sprayed. Sometimes a 91 Octane fuel burns more thus requiring less fuel to be sprayed. But on the other hand, at lower rpms, the lower amount of fuel sprayed leads to loss of torque and engine jerking. Sudden accelerations in a car with wrong fuel will have negative effect. So we also need to keep in mind our driving style. A heavy gas pedal usage in the city will require lower octane while you can make use of premium fuel on the highways with light gas pedal usage.
So, what needs to go in your car? In one word, 87 Octane if you drive from home to office in a regular car.
That's not to say that 91 Octane doesn't serve its purpose.
At the time of writing this article, fuel prices in India have reduced by 90 paise. The current prices stand as mentioned below.
87 Octane - INR 72.16 per liter ( 4.92 USD per gallon)
91 Octane - INR 81.57 per liter ( 5.59 USD per gallon)
Even if you are sure premium fuel helps in increasing the efficiency, it has to be atleast 15% more to justify the higher fuel price. But here are some facts you need to know.
1. Read the manual: Cars and bikes today are compatible to a variety of fuels. To cater to various engines gas companies have also taken the extra step and now we have fuels ranging from E85( Ethanol) to regular 87 Octane all the way till 97 Octane. Yes, it's true that some high-end cars like Ferrari and Bentley's run only on 97 Octane but running your cars on such fuels will not make your cars go faster; your wallets might be lighter though. Ferrari's and Bentleys can run on normal petrol too if the company programs the ecu's to let them. All it will do is reduce the Horsepower numbers which they so bravely boast.
When in doubt stick to the manual. The manual on my Mitsubishi Lancer suggests atleast 87 Octane while the manual for Honda Fit/ Jazz and Royal Enfield Suggest to use 91 Octane petrol or higher. If you are not sure what to use, stick to what is recommended. I fill premium petrol when any of my car is to go through heavy stress (extreme stop and go traffic for 10+ kms or hill climbs).
PS: Most Premium fuels are just regular fuels mixed with Octane boosters. You can fill regular fuel and go for Octane boosters for much lesser money.
2. Your ECU knows: Almost all new cars of today have emission sensors fitted. These sensors have the ability to detect what petrol is being used and tune the engine accordingly. So irrespective of which fuel you use, your car will make the best use of that fuel. If it is 87 Octane the car will lower the compression and if the fuel is 91, it will burn the fuel completely.
PS: Higher Octane count doesn't mean the petrol has more energy, in fact higher Octane has less energy than 87 Octane.
3. Compression Ratio : The ratio of the volume of its combustion chamber from its largest capacity to its smallest capacity is called compression ratio. The higher the ratio, the more it makes sense to use a premium fuel and lower the ratio, better it is to use normal fuel. In such a case if normal fuel is used in a high compression engine, the engine is susceptible to engine knocking. So the next time your engine knocks, check for the fuel used.
4. Engine type: Naturally aspirated small capacity engines used by people everywhere are not able to make efficient use of Premium fuels. The benefits from using premium fuels in such cars will draw minor benefits. On the other hand big engines/ turbocharged cars will make better use of premium fuels. Hence a Ferrari will run better on a 97 Octane while our small engined Tata cars will run better on 87 octane.
5. Driving Style: Our driving styles affect the petrol usage a lot. The amount of fuel as per requirement from the gas pedal is sprayed into the engine via a Fuel Pressure regulator. When the gas pedal is pressed more, more fuel is sprayed. Sometimes a 91 Octane fuel burns more thus requiring less fuel to be sprayed. But on the other hand, at lower rpms, the lower amount of fuel sprayed leads to loss of torque and engine jerking. Sudden accelerations in a car with wrong fuel will have negative effect. So we also need to keep in mind our driving style. A heavy gas pedal usage in the city will require lower octane while you can make use of premium fuel on the highways with light gas pedal usage.
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