E85 Injector Sizing

What Size injectors when running E85?

This is becoming a very common question. The answer is not as easy as straight forward as I wish it was. I will try to explain a simple calculation to get an idea to guide you in the right direction.

First things first. You will need to determine your base injector size. This is the size that you should be running on gasoline. To find this size, simply use the calculator on our site located here. Now that you have determined your base injector size you will need to determine the difference in size to run E85 Fuel. The way to do this is to do some simple math. You are going to use the multiplying factor of 1.47 to get your size. The 1.47 number represents the difference between the stoiciometric fuel ratio of gasoline and E85. Gasoline is 14.7 and E85 is 10.0

Now that you have the "magical" factor and your base injector size, do the math. I will do one with you just to show an example.

Let's say that in the Injector size selection guide size calculator, you came up with a size of 42lb injector needed to reach your HP goals. Simply take the number 42 and multiply this by 1.47.


42 X 1.47 = 62lb Injector

*Note that this is not THE absolute number, but rather a GUIDE to help you determine the size of the injector. Good luck on your mission to use a renwable fuel!