CARB Compliance / Exemption Warning: If you live in California and your application for this product is not CARB Compliant / Exempt, then you cannot purchase it for public highway or street use (in that case it could only be used for formally sanctioned race use on a racing vehicle that may never be used on a public highway or street). If your application is not CARB Compliant / Exempt and you're shipping to California, our system will let you know on the final checkout page.This manufacturer has a policy which prevents shipment to California for applications of this product that are not CARB Compliant / Exempt. Therefore, if you live in California, you will not be able to receive your part if it does not have a CARB EO #, even if it is for a dedicated race vehicle.
What is a Flex Fuel Kit in simple terms? It is basically a special sensor installed along one of your fuel lines that reads the amount of ethanol in your fuel, produces a signal, and sends a processed version of that signal to your ECU for use by your tuning device. Combined with a tuning device, it converts your Subaru WRX STI to run on higher concentrations of ethanol (like E85) than is in standard pump gas.
TIP: Your gas tank is not required to just have all E85 fuel in after installing this kit. It can have any combination of E85 and non-E85 gasoline in it. The COBB AccessPORT will automatically adjust your tune on the fly as needed for your current fuel mixture.
When combined with a COBB AccessPORT, this these E85 flex fuel kits allow you to run E85, which is an ethanol based biofuel and gives huge power and torque gains. E85 also allows your turbo to spool earlier and faster, and causes your engine and turbo to operate considerably cooler and smoother.
An updated version of select COBB flex fuel kits now includes a CAN gateway system. In the past, flex fuel kits required you to tap into or hijack a 0-5V sensor. This means that you will now be missing one readout from the factory ECU. The CAN gateway module allows you to inject aftermarket sensor data, like flex fuel readings, into the factory ECU! This way you can maintain all factory readouts while adding more data to the system. Note only does this include the flex fuel data, but add-on options like fuel pressure safety sensors as well. In addition, installation is simplified.
The widespread use of E85 and its availability has made it a viable option for those looking to maximize power. With its extremely high octane rating, E85 results in tremendous power increases, especially on turbocharged engines. Seeing that potential, COBB designed these simple direct fit kits to take advantage of this and really bring out the best in your Subaru WRX STI.
These COBB Flex Fuel kits are designed to directly bolt and plug into your Subaru WRX STI. From there, your COBB AccessPORT tune takes care of the rest! Since the ethanol content sensor feeds live data to the ECU, you can run full E85 or any blend you want - there is no need to even keep track of how much E85 fuel you fill up with!
Key Features:
- Huge increases in horsepower and torque. Generally the best bang for your buck power adder you can purchase.
- Designed to be Plug and Play (PnP). Tuning is still required after install, unless you load an existing COBB Flex Fuel calibration.
- Includes a OEM quality ethanol content sensor, Plug and Play (PnP) wiring harnesses (no cutting/splicing of wires), connectors, wiring, and misc. hardware.
- Can be used with full E85 or a blend, or even just normal pump gas.
- Does not require additional tuning for a blend; the ECU can take this into account with the AccessPORT tune.
- Select kits now use a CAN gateway, which simplifies installation and does not use up any factory 0-5V sensors. All fuel data is sent to your ECU directly via the COBB CAN gateway device (which connects to your factory CAN bus)!
More Details / FAQ
Q:
What is E85 and why does it easily give so much more power?
A: E85 is a biofuel composed of up to 85% ethanol. The remaining 15% of the fuel is traditional gasoline. Keep in mind the ethanol percentage can be lower during the winter months in some areas. The ethanol often is made from corn and is the same type of alcohol you would find in hard liquor, with the exception that fuel ethanol is denatured with additives to make it undesirable and harmful to drink.
The main reason E85 allows for some much more power than traditional gasoline is that it has a very high octane rating, usually from around 100 to 105 octane, compared to 91 to 93 octane from normal gasoline. This high octane rating allows E85 to resist engine knock. Engine knock occurs when areas of the air fuel mixture ignite before the should due to excessive heat for the fuel type used. This is bad because it can cause extra stress on the engine, and doesn't make optimal power either. From the factory, a new engine is almost always "knock limited", which means it cannot achieve its maximum design power on normal gasoline due to engine knock occurring. E85 basically eliminates this constraint, allowing the engine to achieve the maximum power possible. This especially applies to engines that are turbocharged from the factory.
One nice side effect of that is that extra E85 fuel will help cool your combustion chamber and turbo, and thus help maintain maximum power and reliability. E85 fuel is also generally a lot less expensive than normal pump gas too!
Vehicles sold in the U.S. are designed to operate correctly on the factory tune when using fuel that contains between 10% (E10) and 15% (E15) ethanol. E10 is normally found at almost every standard gas pump in the U.S., so you most likely fill up with it all the time. The reason for this is that ethanol has been found to reduce overall emissions while keeping engine performance strong (see
https://afdc.energy.gov/fuels/ethanol_benefits.html for more information).
Q:
Why a Flex Fuel kit?
A: The "Flex Fuel" part of this kit refers to the ability to run a varying amount of ethanol without having to re-tune or worry about exactly how much E85 you filled up with. In general, the more you fill up with, the more power you get, up to a certain extent. 30-50% ethanol is a typical range for maximum performance and efficiency.
Q:
Ok, so what do I need to buy?
A: All you need is this COBB Flex Fuel Kit and a COBB AccessPORT, along with some E85. Your tuner might also find you need larger injectors and a bigger fuel pump, depending on your power goals. This flex fuel kit constantly monitors how much ethanol is in your fuel, and then tells your ECU. The COBB AccessPORT dynamically recalibrates your ECU to give the optimal power gains on any percentage of ethanol you happen to have in your tank.
Q:
Is a custom tune necessary?
A: Yes, unless you load an existing COBB Flex Fuel calibration. A custom tune, in general, will result in better power gains.
Installation Info: This product requires a COBB AccessPORT. To experience the power gains of this product, you will also need access to E85 fuel.
