Fueling is a mission-critical task and must be done right to safely reach output goals. USRT's reputation as fueling experts is tied directly to our research and product development efforts. Feel free to send us an email or an IM with any questions. We will respond with guidance towards a complete solution.

Injector Spray Patterns

 Factory engineers have gone to great lengths to make sure that fuel is injected in the correct spray pattern for each cylinder head design. Meanwhile, tuners have put up with cold start problems, lumpy idles, misfires and other problems for years. A major reason for this is injectors that are mismatched to the application.

The picture on the left shows a 16v inlet port in detail. A central bridge is clearly visible. This is where the main inlet port becomes split to direct air (and fuel) towards the intake valves. The correct injector type for this inlet configuration is one where the injector nozzle sprays precisely-split fuel streams directly into each port and onto the back of each inlet valve.

Contact with the metal walls is carefully avoided. An injector that sprays a single-narrow fuel cone will wash down the manifold and head. Tuning/holding precise air/fuel ratios is thusly complicated because fuel puddles and then slowly dribbles into the combustion chamber. So much for EFI precision!

Crossflow 8v and VR6 12v are more easily taken care of with conventional injectors. Fuel is atomized after impact with the valve itself or, better yet, directly at the injector tip.

Click to download injector videos (400kb - 1.5MB).

Engines are not generic.

Neither are fuel injectors.

Injector Impedance:

It is also important to understand that fuel injectors come in two electrical flavors -high and low-impedance. VW ECUs require high-impedance but many standalone systems are equipped to manage the lows. The primary advantage of low-impedance injectors is their faster response time. (That is, the speed at which they can be turned on/off.) When very large injectors (e.g. >580cc) are fitted, low-impedance injectors are much easier to tune for proper idle quality and for use at extremely high rpms. The primary advantage of high-impedance injectors is the fact that less heat is generated in the drive circuit and thusly less complex/expensive circuitry is required. Again, if you have a VW ECU you absolutely must use high-impedance parts.

USRT offers fuel injectors for many engines. Non-VW/Audi options are available by special request. Please consult with us for fitment details.

Fuel Injectors (High-Impedance)
Fuel Injectors (Low-Impedance)
Injector Accessories

Fuel System Cleaners

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