The key difference between 91 and 95 octane fuel is that 95 octane fuel can withstand a high compression before ignition than 91 octane fuel.
Octane rating is a standard measure of the performance of a fuel. In other words, it is the measure of a fuel’s ability to resist knocking effect during the combustion. There are different fuel grades according to the octane rating. 91 and 95 octane fuels are such two grades.
CONTENTS
1. Overview and Key Difference
2. What is Octane Rating
3. What is 91 Octane Fuel
4. What is 95 Octane Fuel
5. Side by Side Comparison – 91 vs 95 Octane Fuel in Tabular Form
6. Summary
What is Octane Rating?
Octane rating or octane number is a measurement of the fuel’s performance. It measures the antiknock properties of a fuel. In other words, it rates a fuel according to the relative knocking effect. When rating a fuel, the reference fuel is a mixture of isooctane and heptane.
Figure 01: Different Octane Fuels
Isooctane shows a minimal knocking effect; thus, it has 100 octane rating while heptane shows a maximum knocking effect. Therefore, heptane has 0 octane rating. Then, 91 octane fuel performs similarly to a mixture of isooctane and heptane in a ratio of 91:9 (the mixture contains 91% isooctane and 9% heptane).
What is 91 Octane Fuel?
It is a form of gasoline that has a performance similar to a mixture of isooctane and heptane in a ratio of 91:9. The cost of this fuel is low compared to other forms of octane fuel. It is suitable to use this fuel in low-performance diesel engines, which require a low compression ratio. Further, this fuel is ideal for diesel engines because these engines do not compress the fuel but air (then the engine injects fuel into the compressed air which heats due to compression). Using this fuel instead of high octane fuels can cause engine knocking.
What is 95 Octane Fuel?
It is a form of gasoline that has a performance similar to a mixture of isooctane and heptane in a ratio of 95:5. The cost of this fuel is high compared to other forms of octane fuel. It is suitable to use this fuel in high-performance gasoline engines, which require a high compression ratio.
What is the Difference Between 91 and 95 Octane Fuel?
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91 vs 95 Octane Fuel |
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| A form of engine fuel having a performance similar to a mixture of isooctane and heptane in a ratio of 91:9. | A form of engine fuel having a performance similar to a mixture of isooctane and heptane in a ratio of 95:5. |
| Reference | |
| Resembles its reference fuel, a mixture of isooctane and heptane in a ratio of 91:9. | Resembles its reference fuel, a mixture of isooctane and heptane in a ratio of 95:5. |
| Performance | |
| Suitable to use in low-performance diesel engines. | Suitable to use in high-performance gasoline engines. |
| Cost | |
| Cheaper than 95 octane fuel. | Expensive than 91 octane fuel. |
Summary – 91 vs 95 Octane Fuel
Octane rating is a measurement of the performance of a fuel. Therefore, fuels are in several forms depending on the octane rating.91 and 95 octane fuels are two such forms of fuel. The difference between 91 and 95 octane fuel is that 95 octane fuel can withstand a high compression before ignition than 91 octane fuel.