E85 and Flex Fuel: What Perth Performance Drivers Need to Know

E85 ethanol fuel has become one of the most talked-about topics in Perth's performance community - and for good reason. Used correctly, it's one of the most effective performance upgrades available, unlocking power gains that petrol simply can't match at the same level of safety. Used incorrectly, it causes lean conditions and engine damage. This guide cuts through the confusion.

What Is E85 and Why Does It Make More Power?

E85 is a blended fuel containing approximately 85% ethanol and 15% petrol. Ethanol has a significantly higher octane rating than premium unleaded - around 108 RON versus 98 RON for the best pump petrol in Perth. This means an engine tuned for E85 can run considerably more ignition timing advance and, on boosted engines, more boost pressure, without the risk of detonation.

The result is a large, safe power gain on any engine with a tune that takes advantage of the fuel's properties. On a turbocharged LS or a supercharged HSV, the difference between a petrol tune and an E85 tune can be 50–100+ kilowatts at the wheels.

What Your Car Needs to Run E85

Running E85 is not as simple as filling up and driving. Ethanol requires approximately 30% more fuel volume than petrol to achieve the correct air-fuel ratio. This means your fuel system needs to be able to supply that additional volume. In practical terms, most stock fuel systems on naturally aspirated vehicles can handle E85 with a tune and injector upgrade. Boosted applications almost always require upgraded injectors, and often an upgraded fuel pump, to maintain safe rail pressure at high demand.

A dedicated E85 tune is non-negotiable. Running E85 on a petrol tune will cause severe lean conditions. BYE Performance performs custom E85 tunes on our Dynapack dyno and can advise on exactly what your fuel system needs before we start.

Flex Fuel: The Best of Both Worlds

A flex fuel system adds an ethanol content sensor to your fuel line and connects it to the ECU. The tune then adjusts fuel and timing in real time based on the actual ethanol percentage in the tank - meaning you can run any blend from straight petrol to full E85 and the engine management adapts automatically. This is particularly useful in Perth, where E85 availability varies and BP's 98 RON remains the fallback.

Link ECU (available at BYE Performance) has native flex fuel support built into the G4X and G5 platforms, making it an ideal choice for builds where fuel flexibility is a priority.

Where to Get E85 in Perth

E85 is available at a growing number of service stations across the Perth metro area, including selected United and Caltex (now Ampol) sites. Availability changes, so checking the current list before a track event is always wise. For reference, United's Bibra Lake and Wangara sites have historically been reliable Perth sources.