Brentuning Subaru Flex Fuel Package – WRX 2015+


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Product Description


Add 60+hp over pump gas!

This package includes:
-Cobb Flex Fuel Kit
-Deatschwerks DW65C 265LPH Fuel Pump & Install Kit
-Labor For Install
-Custom Dyno Tuning


A complete plug and play solution enabling users to convert their supported Subaru WRX to a Flex Fuel configuration without losing factory compensations. This is the easiest to use and most sophisticated Flex Fuel kit on the market. Utilizing OEM fuel and electronic connectors, the Ethanol Sensor Kit measures the ethanol content of fuel being fed to the motor. That data is then converted into a signal that the ECU can use for adjusting calibrations and to be displayed on a custom Accessport monitor.

Fuel System Considerations

As with other DIT platforms i.e. VW, BMW, Mazda, the fuel pumps in Subaru DIT vehicles are not designed for ethanol use beyond 10-15%. That said, ethanol levels between 15-30% are generally well tolerated. Those comfortable with mild risk can run ~E30 and enjoy improved knock resistance, charge air cooling, and a mild improvement in engine power potential. For best power results, 50%-65% ethanol is ideal.

On DIT platforms not set up for flex fuel from the factory, at greater than 30% concentration, ethanol has caused oscillating fuel pressure first, progressing to loss of fuel pressure, high pressure fuel pump damage, even making the vehicle inoperable in some cases. Sudden loss of fuel pressure can cause sudden loss of acceleration, stalling, which can reduce braking performance and steering control. Long story short, while the power potential is very attractive, use of high ethanol content fuel is at your own risk.

COBB has performed internal testing in multiple geographic locations with different fuel sources in addition to compiling data from COBB retail shops, our Protuner network, and customers. Results varied significantly. Some users ran several tanks of E85 in a row without issue while some experienced serious loss of fuel pressure in as little as 1-2 tanks of fuel.

We suggest monitoring fuel pressure for oscillations. After having fuel pressure issues, some users were able to flush the HPFP (high pressure fuel pump) out with low ethanol gasoline and get it to operate normally again, while others had to replace the whole pump assembly before they could safely drive the car again. After replacing the pump some users experienced repeat failures if they continued to run E85 fuel.


The Flex Fuel Ethanol Sensor Kit is a requirement for converting your supported Subaru to a Flex Fuel configuration. The Ethanol Sensor Kit measures the ethanol content of fuel being fed into the motor and converts it into data that can be utilized by the car’s ECU.

Features: Subaru Flex Fuel Ethanol Sensor Kit – WRX 2015-2018

Completely Plug and Play Solution
Billet Aluminum Converter Case
OEM Quality Electrical & Fuel Line Connectors
Utilized by COBB Flex Fuel Tables, Retains All Factory Compensations
Custom DTC Error Reporting for Water in Fuel

This package also includes a Deatschwerks DW65C 265LPH Fuel Pump & Install Kit

The DW65c was the industry’s first compact fitment high flow pump. The compact fitment offers easy installation into many modern fuel pump modules where standard sized pumps (such as DW100, DW200, and DW300) cannot be fitted. The DW65c flows 265lph at 40psi and features a quiet and reliable turbine impeller which is compatible with pulse width modulated pump drivers. The pump also features an encapsulated armature for compatability with ethanol based fuels. All DW fuel pumps are backed by a 3 year no fault warranty.

• Weight: 10.1oz (285grams)
• External Materials: Electroplated steel
• Inlet Fitting: 7.7mm ID, 11.0mm OD
• Outlet Fitting: 5/16″ hose clamp
• PRV Activation: 100psi
• Impeller Design: Single Scroll Composite Turbine
• Connector Terminal: Spade pos/neg
• Min Voltage Input: 6 volts
• Max Voltage Input: 18 volts
• Current Draw (40 psi): 12 amps (13.5v)


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Competition use only parts are clearly labeled as competition use only in the product listing page and may only be used according to the guidelines posted on our Emissions Notice to Customers in California page