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Tech: Flex Fuel Shelby GT500

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By EditorTurner

Tech: Flex Fuel Shelby GT500

Flexing Muscle

With AED’s Flex Fuel tune you can pump big power into your GT500

By Steve Turner
Photos courtesy of Advanced Engine Development

Many modern cars are Flex Fuel Vehicles. They feature both the fuel system capacity and the electronic support to seamlessly move betwixt gasoline, which usually has a hint of ethanol these days (E10) and a mixture of gasoline and ethanol, most often sold at the pump as E85. However, most of the performance Fords that we enjoy don’t carry the FFV designation. They are designed to run on a much higher ratio of gasoline. However, thanks to some clever folks in the aftermarket, the flexibility to run between the two fuels is available with a Flex Fuel calibration.

Yes you can make almost 750 horsepower with a stock engine and blower on a 2013-2014 Shelby GT500 with a few upgrades and a Flex Fuel tune. That’s just what Tony Palmer of Palmer Signs wanted for his rolling company business card.
Yes you can make almost 750 horsepower with a stock engine and blower on a 2013-2014 Shelby GT500 with a few upgrades and a Flex Fuel tune. That’s just what Tony Palmer of Palmer Signs wanted for his rolling company business card.

One such outfit is Advance Engine Development in Shingle Springs, California, which has had good success developing packages including the tuning and fuel system upgrades to support the transformation into performance FFVs.

“Flex fuel tunes work via logic based on the front oxygen sensors to determine the Ethanol content of fuel after a fill-up of three gallons or more,” AED’s tuner and engine build Shaun Perry explained. “After an increase of three gallons or more is detected the ECU monitors fuel trims at part throttle between roughly 1,000 and 3,000 rpm. Based on the front O2 trim data, the ECU will adjust the tune for the new Ethanol blend in the tank.”

The hardware upgrades on this engine are quite modest. A VMP TwinJet throttle body, high-flow inlet elbow and a JLT CAI feed the stock blower fitted with a 2.4-inch pulley. On the exhaust side, the mods are even milder, just a high-flow mid-pipe opens things up. Of course with a Flex Fuel tune, the fuel system enhancements are key, and it’s a set of ID1000 injectors, a JMS FuelMax and an AED fuel filter that get the job done.
The hardware upgrades on this engine are quite modest. A VMP TwinJet throttle body, high-flow inlet elbow and a JLT CAI feed the stock blower fitted with a 2.4-inch pulley. On the exhaust side, the mods are even milder, just a high-flow mid-pipe opens things up. Of course with a Flex Fuel tune, the fuel system enhancements are key, and it’s a set of ID1000 injectors, a JMS FuelMax and an AED fuel filter that get the job done.

With just 10 minutes of driving at a light load the factory computer uses the parameters set by Shaun to adapt to the higher ethanol content in the fuel. Once the PCM assesses the situation, the car is ready for maximum performance.

Seeking this type of performance for his 2013 GT500 was Tony Palmer of Palmer Signs in Roseville, California. His Shelby features an eye-catching wrap and thanks to a few select mods and the AED Flex Fuel tune, the car backs up those looks with stout performance. Among the hardware upgrades are a several upgrades to the stock TVS blower, including a 2.4-inch pulley, a VMP Performance high-flow inlet elbow, a VMP TwinJet 67mm throttle body and a JLT Performance cold air intake. On the fuel system side, AED expanded the capacity of the stock system with Injector Dynamics ID1000 fuel injectors, a JMP Chip & Performance FuelMax fuel pump voltage booster and one of its own fuel filters featuring a 25-micron stainless filter element that is a direct replacement for the stock filter.

On pump gas this GT500 is no slouch. It kicked out 663 horsepower and 700 lb-ft of torque burning California’s 91-octane pump gas.
On pump gas this GT500 is no slouch. It kicked out 663 horsepower and 700 lb-ft of torque burning California’s 91-octane pump gas.

This combination and the Flex Fuel calibration resulted in 704 horsepower and 715 lb-ft of torque at the rear wheels on AED’s in-house Dynocom chassis dyno. That’s plenty of power from just filling up with E85 and letting the computer adjust. However, with a more aggressive E85 calibration, those numbers climbed by 42.9 horsepower and 43.7 lb-ft of torque at the wheels.

“This is a Flex Fuel tune, all we did was run the car low on gasoline and add E85, the drive it on the dyno till the dash A/F readout read in the mid-10s while cruising, then we went WOT and power jumped 40 horsepower from Ethanol alone,” Shaun said. “746 rear-wheel horsepower SAE was made when additional timing was added. This tune I labeled as ‘Race’ and although it is also a Flex Fuel tune, it should not be run at WOT with pump gas due to the timing increase.”

Here’s the difference between the Flex Fuel calibration on E85 and the more aggressive Race E85 calibration. By just adding E85 car picked up peak-to-peak gains of 41 horsepower and 15.5 lb-ft of torque. Flashing in the more aggressive E85-only calibration tacks on another 42.9 horsepower and 43.7 lb-ft of torque!
Here’s the difference between the Flex Fuel calibration on E85 and the more aggressive Race E85 calibration. By just adding E85 car picked up peak-to-peak gains of 41 horsepower and 15.5 lb-ft of torque. Flashing in the more aggressive E85-only calibration tacks on another 42.9 horsepower and 43.7 lb-ft of torque!

Of course, if you get comfortable with seamlessly flexing between fuels and you flash in this more aggressive tune for special occasions, you might want a reminder not to fill up with gasoline.

“To minimize to potential for engine damage all tunes with ‘Race’ ignition timing for E85 will have traction control and Advance Track disabled,” Shaun explained. “This tune will show warning lights on the dash for ABS/Traction Control/Advance Track and will clue the customer in that the Race tune with high ignition timing is currently programmed and they should be running E85. The Performance Flex Fuel tune will have Traction control/advance track enabled like stock and have an ignition timing curve for pump gas.”

So with this combo you can easily add power by simply changing fuel and if you want more you can flash in an aggressive E85 tune. Ah, the wonders of technology.

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