Fuel Injectors

What is a fuel injector?

Fuel injectors are electronically controlled mechanical devices. Controlled by your ECU (Engine Control Unit), they are responsible for spraying (injecting) the right amount of fuel into your engine. Not only do they need to deliver the right amount of fuel, it must be dispersed at the right angle, pressure and spray pattern. Most injectors are located in the head of your engine, and threaten into the combustion chamber. 

How does a Fuel Injector Work?

Fuel Injector Function
Fuel Injector Function

Fuel injectors work with more than just your engines ECU. First, your ECU will obtain information about the engines requirements using internal sensors. Once the ECU processes that information, the fuel is drawn from the fuel tank, transported through the fuel lines, and then pressurized with fuel pumps. Proper pressure is checked by a fuel pressure regulator. From there, in many cases the fuel is divided using a fuel rail in order to supply the different cylinders of the engine. Finally, the fuel injectors are ordered to inject the necessary fuel for combustion. 

Increased Power & Air/Fuel Ratio

When you want to add power to your vehicle we automatically think about installing a turbo or a supercharger. Upgrading our turbo or supercharger to a bigger size. Installing a larger high-performance throttle body. Or adding a new exhaust system or intake system to help reduce restriction and increase airflow.  A main component that should not be neglected during these types of upgrades would be your fuel injectors. Without increasing your fuel to your engine, you’re limiting the amount of power your vehicle can produce. It’s important to install fuel injectors that will ensure that fuel flow is proportionately increased, so you can realize the desired gain in horsepower. 

Fuel Injector Clinic Injectors
Fuel Injector Clinic Injectors

When upgrading your vehicles exhaust system, or intake system your supply your vehicle with an increased airflow.  Your increased airflow needs to be matched with an increase of fuel.  Without your injectors delivering the correct amounts, you run the risk of running to lean. Running lean is when your air-to-fuel mixture is to light. The fuel in your ignition chamber is being ignited with too much air, or too little fuel. This can be extremely dangerous for your engine. 

Therefore, when increasing your vehicles air flow, it’s important to increase the fuel. Proper tunes, and the proper fuel injectors can help you avoid potential damage.  Its also wise to have gauges installed in your vehicle to help you monitor your air/fuel ratio. 

Performance Fuel Injectors

Many of the above parts will help increase your horsepower. However many of those parts are in need of performance fuel injectors. High-flow fuel injectors help feed the engine the proper amount of fuel needed to keep your vehicle running properly, or even running at all!  Performance injectors delivering more fuel into the combustion chamber, they will greatly increase your vehicle’s power and performance. Allowing you to get the most out of all your newly installed performance parts. 

DeatschWerks Injectors
DeatschWerks Injectors

There are a lot of factors that need to be considered when deciding which performance fuel injectors to install. Unfortunately Fuel injectors are not a one-size-fits-all type of product. You need to combine fuel type, coil impedance, flow rate, elements of fitment, and tuning data into consideration. 

Performance fuel injectors are classified in according to resistance and flow rate. This is done in lbs. per hour or cc’s per minute. 


The resistance of high impedance, or saturated, injectors is 12-16 ohms. Low low impedance, or peak & hold, injectors range from 0.5-6 ohms resistance. Your injector impedance must match the ECU injector driver.  Most OE ECU’s are set up for saturated injectors. 

Flow Rate

Flow rate is calculated by multiplying horsepower by Brake Specific Fuel Consumption (BSFC). Then you divide by the number of injectors multiplied by the duty cycle. This is  normally not over 80%.

Example: A 4 Cylinder turbocharged engine with an injector duty cycle of 80% 58PSI fuel pressure at idle will need 682cc/min for 400HP.

Fuel Injector Clinic – Flow Calculator

All of this information can become overwhelming very quickly that’s why its always advised when upgrading your injectors to speak to your mechanic, and tuner.  These trained individuals will be able to help you achieve your power goals, and your vehicle running efficiently. Additionally, many fuel injector calculators can be found when browsing through search engines. 

COBB Tuning
COBB Tuning Fuel Injectors

When upgrading your fuel injectors to gain big horsepower, it would be wise to upgrade other components in your fuel system such as your fuel pump, and fuel rail. We cover the importance of those components in a future article. 

Fuel Injector Manufacturers

There are many manufacturers that offer high quality fuel injectors. Some of those companies are:


Fuel Injector Clinic

Injector Dynamics

COBB Tuning

RC Injectors

In Conclusion

Although injectors are such a small part, they have one of the most important jobs of all. Making sure the fuel from the gas tank is properly delivered to the engine! We modify our vehicle for an increased driving experience, or to break new records on the track. The only way that’s able to happen is if our injectors are working properly, and delivering the right amounts.