If you’ve had your 10th gen Civic for a while now and have spent some time on the forums, online, or even read some of our other blogs, then you have no doubt heard about ethanol. You know it’s a type of fuel and you know you can use it to make some more horsepower but what exactly is it and how does it work inside your engine? In this blog we are going to give you a quick 101 on E85 to help you decide if it’s something you might want to add to your gas tank.

Ethanol is a fuel used in combustion engines and is becoming more readily available at local gas stations. It is normally sold as “E85” and is made up of 85% ethanol and 15% unleaded gasoline (i.e. it’s content). Hence the name E85. It’s a popular fuel because it not only burns cleaner than, say your average 91 octane gas, but it also can be a huge performance boost for your engine. 

On the topic of octane, E85 on average has an octane rating of around 105. Now, octane is a measure of a fuel’s ability to withstand things like detonation or knock which can be very harmful to your engine. When we can utilize a fuel that has a higher octane rating, we can do things like add more timing and boost to our tune and in turn make more power. It’s not uncommon to see on average 30-40 more horsepower just by adding an ethanol fuel blend to our L15 and K20C engines.

So how does ethanol make power? Well, it primarily does so in 2 ways. The first being the higher octane rating like mentioned above. The second way it makes power is by the ability of this fuel to cool the boosted air going into your cylinders. Have you ever had a small cut on your hand and then you put some alcohol on it and you got that stingy but very cool feeling? Like the area around the cut just got way colder? Well, that is the principle of how ethanol can make more power. E85 has very good latent heat properties. The incoming intake air charge is very hot and thus not very dense. When ethanol is injected into our engine the liquid gas will absorb tons of heat as it turns into a gas and gets ready for combustion. In doing so, the air is much denser (compacted) and therefore we get more of it and fuel into our cylinders. And you know what that means… more power!

If you want to make big jumps in power and torque then switching to an ethanol-blended fuel is a great way to do it. As mentioned prior, you can see over 30hp to 40hp with just the switch to E85 and tune alone. But there are a few things you should consider before pulling the trigger on this setup.

Consider These Things Before Jumping to E85:

1. You will need flex fuel support enabled

   • You’ll need two things in order to run ethanol. A flex-fuel sensor which is the physical sensor that can read the amount of ethanol content in your gas tank. You’ll also need a tuning device like a KTuner or Hondata to be able to tune your ECU so it knows it has new fuel and can understand how to run the engine correctly. 

2. You will need E85 available

   • You will want to determine if E85 is easily accessible in your area. While some places have it at every pump others might not have an E85 station for hundreds of miles which could be very inconvenient. It might be more of a hassle to find a place to fill up than it’s worth.

3. Your fuel economy will take a hit

   • Ethanol fuel on average takes about 30% more volume compared to gasoline. So while you make more power you will need more of it to make said power. So if MPG’s is your main goal then you may want to pass. If you measure in smiles per gallon, like we do, then pick this up.

A plus with utilizing ethanol fuel in our 10th gen Civics is the fact that our car's ECU is dynamic in the ethanol tuning. What does that mean? It means the car can sense the amount of ethanol in the car at all times and adjust the map accordingly. Running E30 and want all the power? The ECU will give you the boost and the timing to make the most out of it. In the middle of nowhere with no E85 stations in sight? Don’t worry, you fill it up with 91oct and the ECU will pull back the timing and power for safety to keep your car in check. This is a super cool feature that some older cars simply cannot do on stock PCM’s.

In summary, ethanol fuel is arguably one of the best bang for buck mods for modern Honda’s. It can unlock a lot of power with just a sensor and a tuner. It only needs to be set-up once and its relatively low maintenance. Remember, the tricky part here is having a plentiful supply of E85 stations in your area to make full use of the corn juice. 

Drop a comment below and let us know if you found this blog helpful. If you liked it and want to know more about ethanol and some more application-specific tips like desired mixes and ratios, then leave a comment and we might make a 102 blog in the future.

Thanks for learning with us and till next time!

-Vincent