In this blog post, we go over some basics about upgrading your Subaru injectors like injector size and how to wire them in to help you upgrade your engine for more fuel.
Why Upgrade Your Injectors?
When you modify your Subaru for more power, fuel delivery quickly becomes a limiting factor. Bigger turbos, higher boost, or running flex fuel (E85) all require significantly more fuel than your stock injectors can supply. If your injectors can't keep up, you risk running lean - which is one of the fastest ways to damage your engine.
In short, more power = more fuel, and that means upgrading injectors is one of the first supporting mods for a reliable Subaru build.
How Do I Choose The Right Injectors?
One of the biggest mistakes Subaru owners make is grabbing the biggest injectors they can find "just in case." While that might sound safe, oversizing injectors can actually cause drivability problems and make it harder for your tuner to dial in your setup.
The correct injector size should be based on your build, your turbo, and your fuel type. Always talk to your tuner before you buy your injectors since they're the one who will calibrate your ECU.
As a basic rule of thumb:
| Horsepower | General Injector Guideline |
| Under 400 with Flex Fuel | 1050x |
| 401-475 | 1300 |
| 476-600 | 1700 |
| 600+ | 2600 |
Why Don't My New Injectors Just Plug In?
When you upgrade injectors, you'll often find the new injectors use a different connector than what came on your Subaru from the factory. At that point, you have three options:
- Use the adapter that came with your injectors (if included). The issue here is that most of these adapters are generic, universal-fit adapters. They're mass-produced with thin wiring, weak sleeving, and one-size-fits-all connectors that are not designed with Subaru in mind. They'll "work," but they're not built to last.
- Cut and splice the harness directly yourself. While this is possible most DIY tools aren't designed for the specific types of crimps needed for a solid wire to wire connection. A bad connection can easily lead to injector failure and possible engine damage.
- Use our iWire Injector Adapters. These are built with high quality wiring and sleeving and are designed with the proper OEM connectors that match your year and model Subaru. Our adapters are an investment in keeping your injectors and engine healthy for the long run.
Final Step - Get A Tune
Once your injectors are installed and wired in it is essential to program or tune your ECU to accommodate for the new fuel flow.
