For performance enthusiasts, E85 is more than just an alternative fuel - it’s a performance upgrade hiding in plain sight. With an octane rating of 100-105 and unique combustion properties, E85 can unlock significant power gains when properly tuned. Let’s explore how to harness this potential.
Why E85 Makes More Power
Before diving into the how, let’s understand the why:
Higher Octane = More Timing
E85’s 100-105 octane rating (compared to 91-93 for premium gasoline) allows:
- More aggressive ignition timing
- Higher boost levels in forced induction applications
- Reduced risk of knock (detonation)
- Ability to run higher compression ratios
Cooler Combustion Temperatures
Ethanol has a higher latent heat of vaporization than gasoline, meaning:
- It absorbs more heat when changing from liquid to vapor
- Intake charge temperatures drop significantly
- Cooler intake = denser air = more power
- Turbocharged engines see the biggest benefit
More Fuel = More Power
E85 requires approximately 30-40% more fuel volume than gasoline. While this sounds like a disadvantage, it means:
- More mass flowing through the engine
- Greater cooling effect
- The potential for richer, safer tunes
Typical Power Gains
Results vary by platform, but here’s what you can generally expect:
Naturally Aspirated Engines
- 5-10% power increase with proper tuning
- Gains come primarily from timing optimization
- Some engines see minimal benefit; others respond well
Turbocharged/Supercharged Engines
- 15-25% power increase is common
- Some setups see 30%+ gains
- Benefits from both timing and boost increases
- Cooler intake temps allow for more aggressive tunes
Real-World Examples
| Vehicle | Gasoline HP | E85 HP | Gain |
|---|---|---|---|
| Stock Mustang GT (S550) | 460 HP | ~485 HP | ~5% |
| Tuned WRX STI | 300 HP | 350+ HP | ~17% |
| Tuned BMW 335i (N54) | 400 HP | 480+ HP | ~20% |
| Built EVO X | 450 HP | 550+ HP | ~22% |
E85 Conversion Options
Option 1: Factory Flex Fuel Vehicles
The easiest path - your vehicle is already designed for E85:
Pros:
- No modifications needed
- Warranty-safe
- Sensors and fuel system already compatible
Cons:
- Limited vehicle selection
- May not be tuned for maximum E85 performance from factory
Option 2: Aftermarket Flex Fuel Kits
Add E85 capability to a non-FFV through a flex fuel kit:
What’s Included:
- Ethanol content sensor
- Wiring harness
- Mounting hardware
- Tuning software or piggyback ECU
Popular Manufacturers:
- eFlexFuel
- Zeitronix
- Innovate Motorsports
- Continental (OEM sensors)
Cost: $300-$800 for the kit, plus tuning
Option 3: Full E85 Conversion
For dedicated track cars or performance builds:
Requirements:
- E85-compatible fuel lines
- Upgraded fuel pump (higher flow capacity)
- Larger fuel injectors (30-40% more flow)
- Custom ECU tune
- Possibly upgraded fuel pressure regulator
Cost: $1,500-$5,000+ depending on platform and components
Essential Upgrades for E85
Fuel System Requirements
E85 requires approximately 30% more fuel volume. Your fuel system must support this:
Fuel Pump:
- Stock pumps often can’t keep up at high power levels
- Upgrade to a pump rated for your power goals
- Popular options: Walbro 450/525, AEM 340/400, DW400
Fuel Injectors:
- Need 30-40% more flow capacity than gasoline equivalents
- Example: If you need 600cc injectors for gasoline, you need ~800cc for E85
- Quality matters - stick with reputable brands (Injector Dynamics, Bosch, DeatschWerks)
Fuel Lines:
- Stock rubber lines can degrade with E85
- Upgrade to PTFE-lined stainless braided lines for peace of mind
- Not always necessary for light use, but recommended for dedicated E85 builds
Tuning Considerations
A proper E85 tune is essential. You can’t just add E85 to a gasoline tune.
Key Tuning Changes:
- Fuel tables: ~30% richer across the board
- Ignition timing: More aggressive (engine-specific)
- Boost targets: Can often be increased safely
- Cold start enrichment: More fuel needed for cold starts
Tuning Options:
- Dyno tune: Best results, $400-$800
- E-tune: Remote tuning via datalogs, $200-$500
- Flex fuel tune: Automatically adjusts between E85 and gasoline, best versatility
Popular Performance Platforms for E85
Subaru WRX/STI
One of the most E85-friendly platforms:
- Excellent community support and tuning resources
- Significant power gains (15-25% on turbo models)
- Direct-injection models may need additional upgrades
- Popular choice for flex fuel kits
Ford Mustang (EcoBoost & GT)
Strong E85 response across the lineup:
- EcoBoost models see 50+ HP gains with proper tune
- GT (Coyote) responds well to E85
- Factory flex fuel option on some models
- Large aftermarket support
BMW N54/N55/S55
German turbo engines love E85:
- N54 (335i): Legendary E85 response, 100+ HP gains possible
- N55: Strong gains with bolt-ons and E85
- S55 (M3/M4): Already powerful, E85 takes it further
- Excellent aftermarket flex fuel kit support
Chevrolet Camaro/Corvette
GM performance vehicles with strong E85 potential:
- Many models are factory flex fuel
- LS/LT engines respond extremely well to E85
- Large displacement benefits from cooler combustion
- Huge aftermarket support
Dodge Challenger/Charger (Hellcat/Demon)
Supercharged Mopar muscle on E85:
- Factory calibrated for E85 on some models
- Massive power potential (1000+ HP builds common)
- Supercharger cooling benefits from E85
- Active community of E85 tuners
Flex Fuel vs. Dedicated E85
Flex Fuel Setup (Recommended)
Run any blend from pump gas to E85:
Advantages:
- Use E85 when available, gasoline when not
- Automatic blend detection and adjustment
- No range anxiety
- Best of both worlds
Requirements:
- Ethanol content sensor
- Flex fuel tune
- Adequate fuel system for E85 at full power
Dedicated E85 Setup
E85 only, no flex fuel capability:
Advantages:
- Simpler tuning (one fuel only)
- Can run more aggressive tune
- Slightly cheaper (no sensor needed)
Disadvantages:
- Can ONLY use E85
- Range anxiety if E85 not available
- Can’t travel to areas without E85 stations
For most street cars, flex fuel is the better choice.
Cold Weather Considerations
E85 can be problematic in extreme cold:
The Challenge
- E85 is harder to vaporize in cold temperatures
- Cold starts can be difficult below 0°F (-18°C)
- Winter E85 blends help (lower ethanol content)
Solutions
- Run a gasoline blend in winter (flex fuel setup)
- Install a block heater for extreme cold
- Keep a higher fuel level to reduce condensation
- Some tuners add extra cold start enrichment
Is E85 Tuning Right for You?
E85 Performance Is Worth It If:
- You have access to reliable E85 stations
- You want more power without major engine modifications
- You’re already modifying your car for performance
- You have a platform that responds well to E85
- You’re committed to proper tuning
E85 Might Not Be Worth It If:
- E85 isn’t available in your area
- You want a completely stock vehicle
- Your car doesn’t respond well to E85
- You can’t afford proper tuning
- You live in extremely cold climates
Getting Started
Step 1: Research Your Platform
- Join forums and Facebook groups for your specific vehicle
- Search for E85 build threads and dyno results
- Understand what fuel system upgrades are needed
- Find tuners experienced with your platform
Step 2: Assess Your Fuel System
- Can your stock fuel system support E85 at your power goals?
- Do you need upgraded injectors, pump, or lines?
- Get recommendations from experienced builders
Step 3: Choose Your Approach
- Flex fuel kit for versatility
- Dedicated E85 for simplicity
- Consider your driving patterns and E85 availability
Step 4: Find a Quality Tuner
- Look for tuners with E85 experience on your platform
- Check references and dyno results
- Don’t cheap out - bad tunes cause blown engines
Step 5: Enjoy the Power
Once properly set up, E85 provides:
- Consistent, repeatable power
- Cooler engine operation
- Often better fuel economy at the track (more power per gallon burned)
- The satisfaction of running race-grade octane daily
The Bottom Line
E85 is one of the best-kept secrets in performance tuning. With proper preparation and tuning, it can provide significant power gains safely and affordably. The key is doing it right: adequate fuel system, quality tune, and a platform that responds well to ethanol.
For enthusiasts willing to put in the research and investment, E85 offers performance benefits that rival expensive octane boosters and race fuels - available at your local gas station.
Ready to find E85 near you? Use our E85 station locator to find stations along your route.
