E85 Conversion Fuel System Requirements And Tuning

So, you're thinking about switching to E85? That's fantastic! E85, with its high octane rating and renewable nature, can offer a significant performance boost, especially for turbocharged or supercharged vehicles. However, it's not as simple as just filling up the tank. Converting to E85 requires careful consideration of your fuel system and proper tuning. This article will walk you through the key requirements, potential issues you might encounter, and how to solve them, helping you make a smooth and successful transition.

Fuel System Upgrades: The Foundation of E85 Conversion

E85 contains significantly less energy per gallon than gasoline. This means your engine needs to burn more fuel to produce the same amount of power. Therefore, upgrading your fuel system is paramount.

Fuel Injectors: Size Matters

Your stock injectors are likely undersized for E85. You'll need to upgrade to larger injectors that can deliver the increased fuel volume. How much larger? A general rule of thumb is to increase injector size by about 30% compared to what's required for gasoline at your target horsepower. For example, if you're aiming for 400 horsepower on gasoline with 440cc injectors, you'll likely need injectors in the 550-600cc range for E85. Consult a professional tuner or injector manufacturer's calculator to determine the precise size needed for your specific application.

Potential Issue: Choosing injectors that are too small will result in fuel starvation, leading to poor performance, engine knock, and potentially catastrophic engine damage. Injectors that are too large can cause idle issues and poor fuel economy.

Solution: Thoroughly research and calculate your injector requirements before purchasing. Don't guess! Double-check your calculations with a professional tuner. A good tuner will ask about your power goals, engine modifications, and vehicle specifics to ensure you get the right size.

Fuel Pump: Keeping Up with the Demand

Larger injectors need a fuel pump that can keep up with the increased flow. Your stock fuel pump might struggle to deliver the required fuel pressure and volume, especially under high demand. An upgraded fuel pump is essential to maintain consistent fuel delivery and prevent fuel starvation.

Potential Issue: Fuel pump whine, hesitation during acceleration, and lean air-fuel ratios under boost are signs of an insufficient fuel pump. Running lean on E85 can cause severe engine damage very quickly.

Solution: Replace your stock fuel pump with a high-flow aftermarket pump. Walbro, AEM, and DeatschWerks are popular brands known for their reliability. Consider an in-tank pump for ease of installation or an external pump for higher flow capabilities, especially for high-horsepower builds. Ensure the pump is E85 compatible, as some pumps are not designed to withstand the corrosive properties of ethanol.

Fuel Lines: Ensuring Compatibility

While not always strictly necessary, upgrading your fuel lines is often recommended, especially if you're running older or stock lines. E85 can degrade some rubber and plastic fuel lines over time, leading to leaks and fuel delivery problems.

Potential Issue: Fuel leaks, a strong fuel smell, and degraded fuel lines are clear indicators of incompatibility. Fuel leaks are a serious fire hazard.

Solution: Replace any rubber or plastic fuel lines with Teflon-lined (PTFE) fuel lines, which are resistant to ethanol. Stainless steel braided lines offer added protection and durability. Always use fuel-rated hose clamps to ensure a secure and leak-proof connection.

Fuel Filter: Keeping it Clean

E85 can loosen deposits in your fuel tank and lines, which can clog your fuel filter. It's a good idea to replace your fuel filter with a new, high-quality filter when converting to E85 and to monitor its condition regularly.

Potential Issue: Reduced fuel pressure, poor performance, and difficulty starting are signs of a clogged fuel filter.

Solution: Replace your fuel filter with a new one designed for E85 compatibility. Consider using a larger filter or adding a pre-filter to catch larger particles before they reach the main filter. Regularly inspect and replace the filter as needed.

Tuning for E85: The Brain of the Operation

Upgrading your fuel system is only half the battle. You must tune your engine's ECU to properly utilize E85. E85 requires a different air-fuel ratio and timing advance compared to gasoline.

Engine Management System (EMS): Your Options

You have several options for tuning your engine for E85:

Piggyback ECU: This device intercepts and modifies signals from your stock ECU. It's a simpler and often cheaper option, but can be limited in its capabilities.
Standalone ECU: This replaces your stock ECU entirely and offers the most flexibility and control over engine parameters. It's the preferred option for high-performance builds.
ECU Reflash/Remap: This involves reprogramming your stock ECU with a new software map specifically designed for E85. This is a viable option if your stock ECU is capable of supporting the necessary adjustments.

Potential Issue: Using the wrong tuning method or having an inexperienced tuner can lead to poor performance, engine knock, and even engine damage.

Solution: Choose the tuning method that best suits your needs and budget. Research reputable tuners with experience tuning your specific make and model on E85. Don't cut corners when it comes to tuning! A good tune is essential for reliability and performance.

Key Tuning Parameters: Getting it Right

When tuning for E85, your tuner will need to adjust several key parameters:

Air-Fuel Ratio (AFR): E85 requires a richer AFR than gasoline. A target AFR of around 12.5:1 to 13.0:1 is common under boost.
Ignition Timing: E85's higher octane rating allows for more aggressive ignition timing. Your tuner will need to advance the timing to take advantage of this.
Fuel Injector Scaling: This tells the ECU the size of your new injectors.
Fuel Trims: These are adjustments the ECU makes to compensate for variations in fuel quality and operating conditions.
Cold Start Enrichment: E85 requires more fuel during cold starts. Your tuner will need to adjust the cold start enrichment tables.

Potential Issue: Incorrect AFR, excessive timing advance, or improper injector scaling can all lead to engine damage.

Solution: Work closely with your tuner to ensure that all of these parameters are properly adjusted. Monitor your engine's performance closely using a wideband O2 sensor and datalogging tools. Pay attention to any signs of knock or detonation.

E85 Content Monitoring: Ensuring Consistency

The ethanol content of E85 can vary depending on the season and location. It's important to monitor the ethanol content to ensure that your engine is running optimally.

Potential Issue: Running E85 with a lower ethanol content than expected can lead to lean air-fuel ratios and reduced performance. Running E85 with a higher ethanol content than expected can lead to rich air-fuel ratios and poor fuel economy.

Solution: Use an ethanol content tester to check the ethanol content of your fuel. Many modern ECUs can automatically adjust fuel trims based on the ethanol content. If your ECU doesn't have this capability, you may need to manually adjust your tune based on the ethanol content.

Tools and Approximate Costs

Here's a list of tools you might need and approximate costs for an E85 conversion:

Fuel Injectors: $300 - $1000 (depending on size and brand)
Fuel Pump: $150 - $500
Fuel Lines: $100 - $300
Fuel Filter: $20 - $50
Ethanol Content Tester: $20 - $50
Tuning: $500 - $1500 (depending on the complexity and tuner's rates)
Wideband O2 Sensor (optional but recommended): $150 - $300
Basic Mechanic Tools: Wrench set, socket set, screwdrivers, etc. (most people already own these)

Total Estimated Cost: $1240 - $3600 (excluding labor if you're not doing the work yourself)

Final Thoughts

Converting to E85 can be a rewarding experience, unlocking more power and performance from your engine. However, it's crucial to do your research, plan carefully, and work with a qualified tuner. By following the steps outlined in this article, you can ensure a smooth and successful conversion to E85. Remember, safety and reliability are paramount. If you're unsure about any aspect of the conversion process, consult a professional mechanic or tuner. Good luck!