E85 ethanol fuel is one of the most effective performance upgrades available — offering higher octane, cooler combustion temperatures and significantly more power potential. But switching to E85 isn't as simple as filling up at the servo. Here's everything you need to know.
What is E85?
E85 is a fuel blend containing approximately 85% ethanol and 15% petrol. It has a much higher octane rating than standard 98 RON fuel — roughly equivalent to 105+ octane. This allows your engine to run more timing advance and higher boost pressures safely, which translates directly to more power.
Benefits of E85 Tuning
- Significantly more power — Depending on the vehicle, E85 tunes can add 15-30% more power compared to the same setup on 98 octane
- Higher octane rating — Equivalent to 105+ RON, allowing more timing and boost
- Cooler intake temperatures — Ethanol has a high latent heat of vaporisation, cooling the charge air as it evaporates
- Cleaner combustion — E85 burns cleaner than petrol, resulting in less carbon build-up
What Fuel System Upgrades Are Needed?
E85 requires approximately 30% more fuel flow than petrol to achieve the same air/fuel ratio. This means your factory fuel system almost certainly needs upgrading:
- Fuel injectors — Larger injectors that can flow enough E85 at full load
- Fuel pump — An upgraded in-tank or external fuel pump to supply the extra volume
- Fuel lines — Ethanol-compatible fuel lines and fittings (ethanol can corrode some rubber and plastic components)
- Fuel pressure regulator — Depending on the setup, an adjustable regulator may be needed
What is Flex Fuel Tuning?
A flex fuel tune uses a sensor in the fuel line that reads the ethanol content of whatever fuel is in the tank. The ECU then automatically adjusts the tune — fuel maps, timing, boost — to match the actual ethanol percentage. This means you can fill up with E85, 98 octane, or any blend in between, and the car adjusts itself in real time.
Flex fuel is the best of both worlds — full E85 power when you want it, and the ability to run 98 when E85 isn't available (like on a road trip).
Which Vehicles Work Best on E85?
Turbocharged vehicles see the biggest gains from E85 because the higher octane allows more boost and timing. Popular E85 platforms include:
- Ford Falcon FG XR6 Turbo (Barra) — commonly sees 50-80kW gains over 98 octane
- Subaru WRX / STI — significant gains with the right fuel system
- Nissan Skyline / GTR (RB25, RB26) — loves high-octane fuel
- Mitsubishi Evo — excellent E85 response
- Holden VE/VF with supercharged or turbocharged LS — big gains available
How Much Does E85 Tuning Cost?
The cost depends on what fuel system upgrades are needed and the complexity of the tune. A basic E85 tune on a vehicle with adequate fuel system capacity might only require the ECU calibration. A full E85 conversion including injectors, pump, lines and tuning will cost more. Contact us for a quote specific to your vehicle.
E85 Tuning in Ipswich
At Tuned By Luke, we specialise in E85 and flex fuel tuning. We handle everything — from fuel system upgrades to the final dyno tune. If you're in Ipswich, Springfield, Goodna, Redbank Plains or anywhere in the region, give us a call to discuss your E85 goals.