Selecting and Installing Larger Injectors
So you've come to a point where your stock injectors, even with raised fuel pressure, cannot supply the amount of fuel needed to keep the air/fuels within reasonable limits for your (5PSI+) boosted high-horsepower engine.
The next step is pretty simple and logical (well to most of us..), install some bigger injectors, but which ones? And how?
- Typical Fuel Injectors
- Dimensions
- Top Feed, Square Connector
Decide what you need - Step 1
Alright, the first step in deciding what you need involves checking what kind of injectors you currently have in your engine.
Are they Low or High impedance?
What kind of connector do they have?
Top or Sidefeed?
In case of a 4AGE 16v, 4AGZE or 4AGE 20v engine, the injectors are always topfeed, however they can be low or high impedance, or have a resistor pack, also the injectors can have different connectors, depending on what year the engine is.
Generally it's easier for yourself to find some injectors which have the same connectors so you can just drop them in, but sometimes that isn't always an option, a good solution to this would be to find the appropriate connectors, cut off your original ones and solder the new ones on, each connector only has two wires so it's not a big deal, really.
Decide what you need - Step 2
The next step in deciding what kind of injectors you need would be the size of them, how much fuel does your engine need? Generally a good formula to calculate what kind of horsepower you can get out of certain injectors is shown in the image below.
In this case fuel pressure is irrelevant since we use the direct flow rate of an injector, and not the flow rate at stock pressure.
An example:
4 * 182 / 5 * 0.85 = 123,76 HP
Hmm, seems pretty accurate, since my 4AGE engine has 182cc injectors and puts out 121 HP in stock form.
You know what you want!
Let's go buy them!
Good places to buy some used injectors are your local junkyard, a good set of 4 injectors should go for around 20$ to 75$.
Alot of injectors can be found on eBay as well and of course if you like, you can buy new ones too. (Aftermarket or Stock Toyota).
Good manufacturers producing aftermarket injectors are:
- RC Engineering
- HKS
- Greddy
However, prepare to pay big dollars!
Let's move on to the next step, installing those big injectors!
