For the last decade Subaru owners have flocked to the magical land of Ethanol for more power. If you dont know or understand the benefits of running E85 or an ethanol blend, check out our other video here!
**Please note this was written June 20th of 2024 and new support may have released!**
With the new FA24 able to really wake up with a few modifications and tuning, ethanol is a hot topic. It seems like there is a lot of misinformation about flex fuel or ethanol tuning with this specific platform, so today we are spilling the beans and giving you the full and honest truth about running ethanol in your VB WRX.
WHAT IS THE DIFFERENCE BETWEEN ETHANOL AND FLEX FUEL?
I've explained this to 3 VB customers over the last week so dont feel like you're out of the loop. Although they are similar in using the same fuel, they are very different in their practical application.
Ethanol tuning is filling up your car with ethanol, or an ethanol blend, and tuning the car to run on that mixture. Your car will calculate timing, boost, and fuel, based on whichever mixture it was tuned on; E40, E60, E85, etc. If you were to put a different ethanol concentration in the tank, the car would not actively alter its calculations. It would be the same as putting 87 octane in your stock car that should be run on 91 or 93 octane. This could result in the car pulling more timing than the octane rating of the fuel mixture, inducing knock, which can cause engine wear or failure. Its important to run a similar ethanol content to what you are tuned for, out tuner recommends + or - 8%.
Flex fuel tuning is where the ECU makes live adjustments based on a reading from an ethanol sensor. This means you can put 93 octane, E85, or anything in between into the car and the computer will adjust to the fuel it currently reads. Some factory vehicles come equipped with flex fuel, but unfortunately Subaru's do not. Flex fuel can be added in to some Subaru models through aftermarket parts, but currently there are no flex fuel options using the factory ECU for the 2022+ VB WRX.
SO CAN I RUN ETHANOL IN MY VB WRX?
You CAN run E85 or an ethanol blend tune! There are two popular tuning options currently:
Cobb - With a Cobb Accessport, you can tune the car for whatever ethanol content you put in. If you found yourself needing to fill up and dont have ethanol available, you could switch, or flash, the map to a gas map and fill up. Please see more about switching fuels below.
Burger Tuning JB4 - JB4 also supports Ethanol tuning, though I dont know of many tuners that offer custom calibrations for them. Same as the Accessport, you can switch maps via the JB4 app when needed.
BUT BURGER TUNING SELLS A FLEX FUEL KIT FOR THE VB...
Are you sure about that? This is where I find a lot of confusion coming from. I've had a customer come in who purchased this "flex fuel kit" and wanted to know how to use it with their Cobb Accessport, which isn't possible. This kit is simply an ethanol sensor that connects to an app on your phone to monitor your current ethanol content. See more below on that!
BUT I DO NEED AN ETHANOL GAUGE TO RUN ETHANOL, RIGHT?
No! Though you should be monitoring what ethanol content you put in your car some way. Ethanol gauges are nice because they're an easy to read digital display. However, if you fill up and the ethanol content is lower or higher than the range your car should run, you're stuck with that fuel mixture until you burn some and can refill to your target. You can use a shaker test before filling up, in which you test the content using a small amount of ethanol and water. This does require a little work, and sometimes ethanol on your hands, but coming from an experienced veteran of E tuning its not bad for peace of mind.
SO WHATS STOPPING ME FROM SIPPIN SOME E?
While I am a big proponent of running ethanol, there are a few things you need to know, specific to the VB.
- Shelf life: Ethanol is hygroscopic, meaning it absorbs water, even from the air. Obviously water in your gas tank isn't great for combustion, but can also lead to damage, especially your injectors. If you do run ethanol its recommended that you don't let the car sit for over a month or so with the same tank of fuel. If you store the car over the winter its strongly advised that you switch to gas for storage.
- Fuel economy: Ethanol has less energy so you'll use about 30-40% more ethanol than gasoline, which is important for the next part.
- Direct injection: Most new cars, including your VB, are equipped with direct injection, which I'm not going explain here, but yields better fuel economy and less emissions. As far as performance it has a few perks but is not able to flow as much as port injection due to the operating window that direct injection has as RPM's increase. Although ethanol can produce more power, it requires more fuel; and you can only make as much power as you have fuel flow for.
- Fuel system support: While you can upgrade your lift pump, there are currently no drop in upgrades for the VB WRX high pressure fuel pump (HPFP) or DI injectors, although Nostrum is working on some. You can switch to port or dual but that can currently only be run with a port controller or Motec which is $8,000+.
HOW CAN I SAFELY SWITCH FROM GASOLINE TO ETHANOL
In order to do this you'll need to have a 91/93 gas map as well as an ethanol map which you can get here.
The process that our tuner K-Nasty recommends is to drive your car until its under 1/8th of a tank and then fill up with whichever fuel you're switching maps to. After filling up, start the car on the map that you currently have loaded and let it run for 1-2 minutes. This is allow the fuel in the feed lines to clear out. Shut the car off and flash the map to the one for the new fuel type you just put in the tank. From there you can gently drive the car for about 5 minutes. After that point you should be all good to blast off and take your ops to gapplebees.
Ethanol has a lot of great qualities and you can gain most of the benefits from running an ethanol blend tune. By running a tune on E60, you wont need as much fuel flow as E85, you wont burn through fuel as fast, and still get the benefit that ethanol has to offer. You can also find a "calculation" to fill you tank to a pre determined level with gasoline, then top it off with E85. An example is filling the tank to the 1/4 or 1/2 mark, then the rest with E85. This is easily repeatable, and depending on the stability of your local E85 equipped gas station, wont require you to test the ethanol levels every time. A good water-meth kit is another really great option for direct injection cars and expect us to cover that very soon.
If you do have any questions please feel free to reach out to us through our site, email or phone number. Looking for any parts or a tune for your car? We got you covered! Thanks again and well see you soon.