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E85 fuel has gained popularity among performance enthusiasts due to its higher octane rating and potential for increased power output. However, converting to E85 presents unique challenges, particularly regarding fuel injector sizing. This article explores common fuel injector sizing problems encountered during E85 conversions and provides solutions to ensure reliable power.
Understanding E85 Fuel
E85 is a blend of 85% ethanol and 15% gasoline, which offers several advantages:
- Higher octane rating: E85 typically has an octane rating of around 105, allowing for more aggressive tuning.
- Cooling effect: Ethanol has a cooling effect during combustion, which can lead to more efficient power production.
- Environmental benefits: E85 produces fewer emissions compared to traditional gasoline.
Common Fuel Injector Sizing Problems
When converting to E85, one of the most critical aspects is ensuring that your fuel injectors are appropriately sized. Here are some common problems associated with fuel injector sizing:
- Under-sizing: Many enthusiasts underestimate the fuel requirements of E85, leading to insufficient fuel delivery.
- Over-sizing: Conversely, using excessively large injectors can result in poor fuel atomization and drivability issues.
- Fuel flow rates: E85 has a different fuel flow rate compared to gasoline, necessitating adjustments in injector sizing calculations.
- Injector duty cycle: Running injectors at too high a duty cycle can lead to heat issues and injector failure.
Calculating the Correct Injector Size
To achieve optimal performance with E85, it’s essential to calculate the correct injector size. Here’s a step-by-step guide:
Step 1: Determine Power Goals
Define your power goals for the vehicle. This will help in estimating the required fuel flow. For example, if you aim for 500 horsepower, you will need to calculate the necessary fuel flow to support that power level.
Step 2: Calculate Fuel Flow Requirements
Use the following formula to estimate the required fuel flow:
- Fuel Flow (lbs/hr) = (Horsepower x BSFC) / Fuel Density
Where:
- BSFC: Brake Specific Fuel Consumption, typically around 0.6 for gasoline and 0.7 for E85.
- Fuel Density: E85 has a density of approximately 0.79 lbs/gal.
Step 3: Choose Injector Size
Once you have the required fuel flow, select injectors that can support that flow rate while maintaining a safe duty cycle. Aim for a duty cycle of around 80% at peak power to ensure reliability.
Correcting Sizing Issues
If you encounter issues with injector sizing, here are some corrective measures:
- Upgrade injectors: If injectors are undersized, consider upgrading to larger injectors that can meet your fuel flow requirements.
- Tuning adjustments: Work with a tuner to adjust fuel maps and ensure proper fuel delivery across the RPM range.
- Check fuel pressure: Ensure that fuel pressure is within the recommended range for your injectors, as inadequate pressure can lead to poor performance.
- Monitor duty cycles: Use data logging to monitor injector duty cycles during operation to avoid running them too close to their limits.
Conclusion
Converting to E85 can significantly enhance performance, but proper fuel injector sizing is crucial for reliability and power. By understanding the unique requirements of E85 and following the correct sizing calculations, you can avoid common pitfalls and enjoy the benefits of this high-octane fuel.