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How to Pick the Correct Fuel Injectors

by LiMona 27 Jul 2023

What are the types of fuel injectors?


Fuel supply

The top-fed injector is fed with fuel through the top of the injector and mounted on a fuel rail (fuel rail) that distributes fuel to the various injectors. This variant is most often found on cars from the European and American markets.

 A side-fed injector is fed with fuel from the side and mounted in a fuel rail that distributes the fuel to the various injectors. These are most commonly found in the Asian market.

 The top-fed injectors, regardless of brand, often use some Bosch standard measurements, although they may differ slightly in size.



Fuel injector placement

 The selection of injectors is usually made only based on four things.


  1. How much it flows to cope with a peak power
  2. If it is compatible with the control system to be used
  3. Physical size
  4. Is it compatible with the fuel to be used?


Something that is forgotten is what pressure it should work with if it should be run in everyday use or only 2 hours per season, injector character, and spray angle. Here you should review whether you should adapt the injector to the intake you have with fixed mounting points for the injector or whether you should adapt the information to have specific requirements for the type of injector that is suitable for the area of ​​use for the engine. The choice of the electrical connector must also be considered depending on the use area.


The size of Fuel Injectors


The size of the diesel fuel injector is another mistake people make because they think that the size is the same in all of them, but this is not the case. They are entirely different. If you cannot calculate the size, you should talk to the mechanic to get the right size. When your car is fixed with a diesel fuel injector that is not the correct size, it will cause damage to the car, and it can even cause an accident. That’s the reason that you should make sure that you have the correct size.


Injectors and boost


Most fuel injector flow rates are advertised statically at 43.5 PSI. This means that fuel flow is measured while the injector is kept fully open, and fuel is pumped through the injector at a pressure of 43.5 PSI into the atmosphere. To maintain advertised flow rates, the fuel pressure should be raised or dropped by the same amount as the pressure in the intake manifold grows or declines. If static fuel pressure is set to 43.5 PSI and manifold pressure rises to 30 PSI, fuel pressure should increase to 43.5 + 30 = 73.5 PSI. Max HP supported by an injector is calculated to flywheel power. If you do not raise the fuel pressure under boost, the injector will spray less fuel, and if you do not lower the fuel pressure under vacuum, the injector will spray more fuel.



Fuel injector flow matching


Small variations occur when manufacturing injectors, which means that the flow on the injector size can vary by several percent. What differs is due to precision in manufacturing and, of course, the extra manufacturing cost if you make these directly from the factory. Factors that affect the flow are coil winding, injector disc, and valve seal, for example.


The car manufacturers use injectors with the variations the factory must stay within and have huge margins of error instead.


The aftermarket often uses small margins of error due to high power outputs with smaller safety margins and limitations of testing possibilities in a virtual environment as well as practical tests in different conditions.


Therefore, it is good to match the injectors the factory does not make. In short, this means that, for example, 100 injectors are paired to flow within the new framework, which in the aftermarket is usually 1%, which is very good if you compare it with other sources of error that exist that have much more significant variation.


An ECU system can today compensate for fuel on each cylinder with separate lambda and EGT sensors on each cylinder. Still, despite this, it is best to have a set of injectors that flow equally on each cylinder.




The car you just bought costs you a lot, and the only thing you can do is take care of it to ensure it has a long lifespan. If your car runs with the help of diesel, then it will need constant maintenance. Choosing a fuel injector can be confusing, especially if you have yet to decide what to look for. The diesel fuel injector will play a big part in how your car will function. And if you don’t get the right fuel injector, you might destroy the whole engine. When you have a detailed explanation of factors you need to consider before choosing a diesel fuel injector, you will not have a problem.

Our website will provide you with the most professional purchase guidance.


Here is the link you can check and buy aftermarket Fuel Injector online catalog.


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