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Difference between 87 and 91 Octane Gas for Powersports Vehicles

Not all gasoline is the same 

When it comes to filling up your powersports vehicles, such as ATVs, motorcycles, or jet skis, you may have noticed different octane ratings at the gas pump. Two commonly available options are 87 and 91 octane gas. But what exactly is the difference between the two, and which one is right for your powersports vehicle? In this article, we will explore the dissimilarities between 87 and 91 octane gas and help you understand the impact it can have on your vehicle's performance.

Octane Rating Explained

The octane rating refers to the fuel's ability to resist knocking or pinging during combustion. Knocking is an undesirable phenomenon that occurs when the air-fuel mixture detonates prematurely in the engine's cylinders. It can lead to reduced power, engine damage, and decreased fuel efficiency.

The octane rating is a measure of a fuel's ability to resist knocking compared to a mixture of isooctane (100 octane rating) and heptane (0 octane rating). The higher the octane rating, the better the fuel's resistance to knocking.

87 Octane Gas

87 octane gas is the most common type of gasoline available at fuel stations. It is suitable for most regular engines and powersports vehicles. This lower octane rating is sufficient for engines with lower compression ratios, which are commonly found in everyday vehicles.

However, high-performance powersports vehicles often have higher compression ratios, which require a higher-octane fuel to prevent knocking. Using 87 octane gas in these vehicles can result in reduced power output and potential engine damage over time.

91 Octane Gas

91 octane gas, also known as premium or high-octane fuel, has a higher octane rating than regular gasoline. It provides improved resistance to knocking, making it suitable for high-performance powersports vehicles and engines with higher compression ratios.

Using 91 octane gas in your powersports vehicle can offer several benefits. It can provide smoother acceleration, improved throttle response, and better overall performance. Additionally, higher-octane fuel can help to keep the engine cleaner and prevent carbon deposits from building up.

Choosing the Right Octane Rating

When deciding between 87 and 91 octane gas for your powersports vehicle, it is crucial to consult the owner's manual or manufacturer's recommendations. They will specify the minimum octane rating required for optimal performance and to avoid potential engine damage.

While higher-octane fuel may offer benefits for high-performance vehicles, using it in engines that don't require it will not provide any noticeable advantages and may only result in unnecessary expenses.

Ethanol in Gasoline 

Ethanol gas, also known as E10, is a blend of 90% gasoline and 10% ethanol. It has become increasingly popular due to its environmental benefits and potential to reduce dependence on fossil fuels. However, ethanol gas can present some challenges, particularly in colder temperatures or when left sitting for extended periods. In this blog post, we will explore why ethanol gas gums up in the winter or if left sitting too long, and what you can do to prevent it.

What causes ethanol gas to gum up?

Ethanol gas has a higher affinity for water compared to pure gasoline. When exposed to moisture, ethanol absorbs it, leading to the formation of water droplets in the fuel. These water droplets can cause several issues:

  • Phase separation: Ethanol and water can separate from gasoline, forming distinct layers. This separation is known as phase separation and can lead to engine problems.
  • Microbial growth: Water in ethanol gas provides a breeding ground for microbes, such as bacteria and fungi. These microorganisms can multiply and form a slimy substance that clogs fuel lines and filters.
  • Corrosion: Water in ethanol gas can corrode metal components in the fuel system, including fuel tanks, fuel lines, and injectors.

Why does ethanol gas gum up in the winter?

In colder temperatures, the water in ethanol gas can freeze, causing further complications. When water freezes, it expands, potentially blocking fuel lines and filters. Additionally, the presence of ice crystals can disrupt the fuel-air mixture, leading to poor engine performance and starting difficulties.

What happens when ethanol gas is left sitting too long?

When ethanol gas is left sitting for extended periods, it can undergo a process called oxidation. Oxidation occurs when ethanol reacts with oxygen in the air, leading to the formation of gums and varnishes. These deposits can clog fuel injectors, carburetors, and other fuel system components, resulting in reduced engine performance and fuel efficiency.

Use the recommended gas for your vehicle 

Understanding the difference between 87 and 91 octane gas is essential when choosing the right fuel for your powersports vehicle. While 87 octane gas is suitable for most regular engines, high-performance vehicles with higher compression ratios may require 91 octane gas to prevent knocking and achieve optimal performance. Always refer to the owner's manual or manufacturer's recommendations to ensure you are using the correct octane rating for your specific powersports vehicle.


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