85 ethanol fuel, a blend of 85% ethanol and 15% gasoline, has been growing in popularity, especially among performance enthusiasts, environmentalists, and those seeking an alternative to petrol. This fuel is considered a more eco-friendly option compared to regular petrol due to its renewable nature and lower carbon emissions. However, what makes E85 particularly intriguing to car enthusiasts is its potential to increase car performance when used in high-performance engines.
This article will explore the chemistry behind E85, its impact on performance, how it works within an engine, and how to safely and effectively use it to enhance your car’s power output. We will also compare E85 to traditional petrol/gasoline, discuss the advantages and disadvantages, and highlight how you can modify your engine to take full advantage of this high-octane fuel.
The Chemistry of E85
To understand why E85 ethanol fuel can increase performance, it’s essential to grasp the fundamental chemistry behind ethanol and how it interacts with an engine. Ethanol (ethyl alcohol, C₂H₅OH) is an alcohol-based fuel made primarily from fermented crops like corn, sugarcane, and wheat. It is oxygen-rich, meaning it contains more oxygen than traditional gasoline, which is a hydrocarbon fuel.
Here’s how ethanol works in comparison to petrol:
1. Higher Oxygen Content
Ethanol’s molecular structure provides an oxygen content of approximately 35-40%, whereas petrol contains virtually no oxygen. The higher oxygen content allows for more complete combustion in the engine, which can lead to higher efficiency and, in some cases, more power.
2. Octane Rating
One of the most significant advantages of E85 is its high octane rating. While regular petrol typically has an octane rating of around 87, E85 can have an octane rating as high as 105. The higher the octane number, the more compression the fuel can withstand before igniting. This enables high-performance engines to run more boost (higher levels of forced induction), which directly correlates with increased horsepower.
3. Lower Energy Content
Ethanol has a lower energy density compared to petrol, meaning it contains less energy per unit volume. Specifically, ethanol contains about 33% less energy per litre than petrol. However, the benefits of its high octane and ability to run leaner air-fuel mixtures often outweigh the disadvantage of its lower energy density in high-performance applications.
4. Cooling Effect
Ethanol has a higher latent heat of vaporization than gasoline. This means that ethanol absorbs more heat as it vaporizes, which cools the intake air and the combustion process. This cooling effect helps reduce the risk of knock (pre-detonation) and can increase power and engine longevity when used in performance applications.
How E85 Increases Car Performance
When used properly, E85 can unlock several performance advantages, particularly for vehicles with modified engines or those built for high-output applications.
1. Higher Compression and More Power
As mentioned, one of the biggest advantages of E85 is its high octane rating, which allows for more aggressive tuning. Engines that run on higher-octane fuels can achieve higher compression ratios or boost pressures without risking knock (pre-ignition), which would otherwise cause engine damage. This can result in significant power increases, especially when used in turbocharged, supercharged, or high-performance naturally aspirated engines.
For example, when tuning an engine to run E85, a turbocharged car may increase its boost pressure beyond what would be safe on regular gasoline. This increase in boost, combined with E85’s ability to handle more heat and pressure, can lead to dramatic increases in horsepower—often in the range of 10-30% more power compared to petrol.
2. More Complete Combustion
Because ethanol is oxygen-rich, it promotes a more complete combustion process within the engine. Traditional gasoline engines can sometimes suffer from incomplete combustion, where not all of the air-fuel mixture burns efficiently. Ethanol, however, helps to burn all the fuel in the cylinder, improving the engine’s thermal efficiency and reducing the amount of unburned fuel that gets wasted.
More complete combustion can lead to better engine performance across the power band, more efficient fuel use, and lower levels of carbon build-up in the combustion chamber. Additionally, this efficiency can result in higher exhaust gas temperatures, which is beneficial for certain performance applications, like turbocharging, where exhaust gases are used to drive a turbocharger.
3. Reduced Detonation (Knock)
Detonation, also known as knock, occurs when the air-fuel mixture in the engine’s combustion chamber ignites prematurely due to high pressure and temperature. This can lead to a loss of power, increased engine wear, and potential engine failure. E85 helps prevent this by providing better knock resistance due to its high octane rating.
This is especially valuable for forced induction engines (turbochargers and superchargers), which inherently generate higher combustion pressures. By using E85, tuners can increase boost levels without the risk of knock, resulting in more power and a safer running engine.
4. Lower Exhaust Temperatures
The cooling effect of E85 also plays a role in maintaining lower exhaust gas temperatures (EGT), which can be beneficial in preventing engine parts from overheating. With a cooler intake charge and cooler combustion, your engine can maintain performance longer without the risk of heat damage to critical components such as pistons, valves, and turbochargers.
5. Improved Throttle Response
Vehicles running E85 often experience improved throttle response due to the fuel’s ability to provide a smoother and more controlled combustion process. This can translate to more precise acceleration and quicker power delivery, which is particularly noticeable in performance driving and racing conditions.
E85 vs. Traditional Gasoline: Key Differences
To truly understand the benefits of E85, it’s essential to compare it directly to traditional gasoline. Here are the main differences:
| Property | E85 Ethanol Fuel | Traditional Gasoline |
|---|---|---|
| Octane Rating | 100-105 | 87-93 |
| Energy Density | 33% less than gasoline | Higher energy content |
| Oxygen Content | 35-40% | 0% |
| Cooling Effect | High | Low |
| Volatility | Lower volatility | Higher volatility |
| Environmental Impact | Lower CO₂ emissions | Higher CO₂ emissions |
1. Octane Rating
E85 has a significantly higher octane rating, which makes it more suitable for high-performance engines, particularly those with higher compression ratios or forced induction systems. High-performance vehicles, such as turbocharged or supercharged engines, benefit most from E85’s higher octane, which allows for more aggressive tuning and higher power outputs.
2. Energy Density
E85 contains 33% less energy per litre compared to petrol, meaning you will need to use more fuel to achieve the same distance. This lower energy content can make E85 less efficient for daily drivers or non-performance vehicles. However, for high-performance applications where engine modifications allow for more fuel to be burned (i.e., turbocharged or supercharged engines), this loss in energy density is often outweighed by the performance gains.
3. Fuel Economy
The fuel economy of a car running on E85 is typically lower than that of petrol. This is due to E85’s reduced energy content. As a result, you may find that your vehicle consumes more fuel when running on E85 compared to petrol, especially on longer trips or under lighter driving conditions. However, the increase in performance generally compensates for the decrease in fuel economy in performance-oriented vehicles.
4. Environmental Impact
E85 is often seen as an environmentally friendlier alternative to gasoline because it’s made from renewable resources like corn, sugarcane, and other biofuels. Additionally, ethanol produces less CO₂ emissions when burned than gasoline, which is important for reducing the automotive industry’s overall carbon footprint. On the other hand, the production of ethanol also involves energy-intensive farming and processing, which can mitigate some of the environmental benefits.
Modifying Your Engine for E85 Use
To use E85 ethanol fuel effectively, your car’s engine must be adapted to handle the specific characteristics of this fuel. Below are key modifications and considerations for running E85 in your vehicle:
1. Fuel System Upgrades
Since E85 requires a higher flow of fuel to achieve the desired air-fuel ratio, upgrading the fuel injectors and fuel pump is often necessary. Larger injectors are needed to supply more fuel, and a higher-flow fuel pump will ensure that the increased fuel demand is met.
2. Tuning
The engine’s fuel map must be recalibrated to optimize the air-fuel ratio for E85. This is typically done via a custom ECU tune that takes into account the different properties of E85, such as its lower energy content and higher oxygen content. Proper tuning ensures that the engine burns the right amount of fuel for the increased oxygen available, avoiding running too lean or rich.
3. Compression Ratio Adjustments
For maximum performance gains, the compression ratio may be increased to take full advantage of E85’s high octane rating. Higher compression ratios allow for more power to be generated from the combustion process without risking knock or detonation.
4. Fuel System Durability
Ethanol can be more corrosive than gasoline, so it is crucial to ensure that your fuel system components (e.g., fuel lines, injectors, and tanks) are compatible with ethanol. Some components may need to be upgraded to ethanol-resistant materials to avoid deterioration over time.
Conclusion: E85 for Performance Enthusiasts
E85 ethanol fuel offers an exciting opportunity to increase the performance of high-performance vehicles, particularly those with forced induction or high compression engines. Its high octane rating, oxygen content, and cooling effect make it an ideal fuel for tuning vehicles to produce more power.
However, to take full advantage of E85, your car will need to be appropriately modified, including fuel system upgrades, tuning, and ensuring engine durability with ethanol-compatible components. While the lower energy content of E85 can result in decreased fuel economy, the power gains often justify the trade-off for performance enthusiasts and racers.
In the future, as fuel technology continues to evolve, E85 may become a more common fuel choice not only for high-performance applications but also for daily drivers seeking to reduce emissions and improve fuel efficiency without sacrificing power.