Nc Miata with 2015 ford mustang gt injectors

NOTE: This is not a drop in modification and will require tuning of the Engine Control Unit (ECU). This mod is not exclusive to E85 usage.

I have been tuning my 2007 Mazda Miata MX5 (NC) with an open source software for a while. I enjoy tuning as it gives me another level of depth that I can add to my vehicle. I can control and manipulate values to make the vehicle behave any way I want.

I decided to experiment with E85 fuel. E85 is readily available near me and is relatively cheap compared to regular let alone premium. E85 is 70-90% Ethyl Alcohol and 10-30% gasoline. Ethyl Alcohol has roughly 30% less thermal density than standard Gasoline. This means that you will need approximately 30% more fuel to be added to accommodate an engines fuel consumption needs.

Initially while tuning for E85, I had left in the factory injectors (sized at about 270cc/min flow). I found that as I added fuel, that the injectors were reaching a point called static. This is when fuel injectors are held open and are effectively at 100% usage. This happened at around 4700 rpm and was quite short of the 7800rpm rev limit I had set. It was clear, I needed larger injectors.

I am a big supporter of doing research to better understand what options are on the table. There were several options for larger injectors available from online and local sources. However, these options were a little on the expensive side for a set of 4 injectors. I like to see what I can find outside of normal channels and enjoy the challenge.

The 2.0 Liter 4 cylinder engine in the 2006-2015 MX5 is a Mazda/ Ford co-design. This means that there are often parts from both manufacturers that will fit. Fuel injectors fitting this engine are an EV14 Extended design commonly found in many Ford engines from 4-8 cylinders. After looking down the rabbit hole of engines and finding specifications of fuel injector flow rates for multiple engines, I found that the 2015 Ford Mustang GT carries Injectors that have a flow of 34lb/hr. These injectors were only $19 each new from a ford dealer. For the possible net gain, this was too cheap not to attempt.

Once I had them outside the box, I removed the factory Mazda fuel injectors and compared the length and o ring mating surfaces. An exact physical match, and they even came with new o rings! The install was performed without much difficulty and in about half an hour.

In order to swap them, you only need to remove the fuel rail. Be sure not to drop any parts. I recommend the use of safety glasses and to have some form of fire suppression around in case of emergency. You will be dealing with liquid gasoline.

Once installed, the tune was revised and I found that the injectors are in fact large enough to satisfy this engine in its current state of tune with E85.

What are the benefits of E85 when you don't have a turbo?

1. E85 has a static octane rating of 100 (United States). This means that engines that are knock limited even in naturally aspirated form can benefit with added ignition timing.

2. There is a lesser-known volumetric efficiency gain due to the thermal reduction caused by the Ethyl Alcohol in E85. When vaporizing Ethyl Alcohol, it carries away a large amount of heat. During this cooling, the air charge shrinks and can carry in a larger charge of Oxygen. This will cause an engine to consume a larger amount of fuel during peak torque and peak horsepower to accommodate for the extra oxygen.

   
   

What about the downsides with E85?

1. Fuel consumption. Get ready to have at LEAST 15% fuel mileage decrease.

2. Hard to start in cold weather even with a good tune.

3. Depending on your preferences, the smell of E85 can be an unpleasant odor.

   
   

Be careful when considering E85. Be sure that you or your preferred tuner can handle the changes needed for this modification.

Happy Modding!

-Anthony Lleras

Youtube

Instagram

DISCLOSURE: I purchased all these items with my own money and the company had no prior knowledge to this promotion. All opinions are my own. I am affiliated with this company but I do not make a commission on any purchase you make through my link(s).