Thanks to Matt Robinson from Gearhead Automotive Performance for his assistance in providing information used in this guide for selecting the proper injector for a 7.3L Power Stroke Diesel.

One of the most common questions asked by people looking to increase the performance of their 7.3L Power Stroke is, "What size injectors should I go with?"

A pretty reliable rule of thumb is that a 7.3L HEUI injector will produce approximately 2.25 to 2.30 RWHP for every CC of fuel that you can use effectively. This does not takes into consideration different power adders such as Nitrous or Water/Meth, but does assume that you have enough airflow (ie. turbocharger) to provide the oxygen necessary to properly consume the fuel. This also goes on the assumption that there is enough oil volume in the High Pressure Oil Pump (HPOP) to generate at least 2800 PSI in the peak HP RPM range (usually 2600-3000 RPMs). All numbers are also based on single shot injectors unless otherwise indicated.

Common street nozzles are 30% Extrude Honed (EH), while 80% and 100% Electric Discharge Machining (EDM) nozzles are more common on racing applications. The larger nozzles allow you to push the power peak up into the higher rpms and make more HP.

Again, there are so many variables (compression, HPOP stability, injection pressure, airflow, fuel quality, timing, and many others) that these are merely general guidelines for power output... not hard, fast rules.

The general Rule-of-Thumb for peak power without nitrous, but a properly matched turbo is as follows:

Stock Injectors:

Modified Injectors:

The next question we are often asked is, "What is the difference between "Stage 1", "Stage 2", "A Codes", "B Codes", and "Hybrid" injectors?"

To start with, different stage injectors are merely variations in chamber volume and nozzle size. In order to change the maximum volume characteristics of the injector, a replacement plunger and barrel is used to increase the size of the injection chamber that holds the fuel. Let's take a closer look...

A Code Injectors:

All Power Stroke and International T44E engines use "A Code" injectors (AA to AF) which uses a 6.0mm plunger and a 16mm intensifier piston to produce a 7.111:1 multiplication in pressure. This means that for every 1 PSI of Injection Control Pressure (ICP) from the HPOP, the injected fuel pressure will be 7.111 psi. So, on a system running 3,000 PSI of ICP, the pressure of the injected fuel will be 21,330 PSI (not taking into account base cylinder pressure).

B Code Injectors:

International DT466 and I530 engines use "B Code" injectors (BA to BN) and are relatively identical to many of the "A Code" injectors except for the "BD Code" injector which uses a 7.1mm plunger and a 17.5mm intensifier piston to produce a 6.075:1 multiplication in pressure. For "BD Code" injectors, on a system running 3,000 PSI of ICP, the pressure of the injected fuel will be 18,225 PSI (not taking into account base cylinder pressure). This is quite a bit less than the Power Stroke and requires about 15% higher ICP pressure to achieve the same injected fuel pressure. Also, because of the large intensifier piston, the HPOP will also need to be able to supply roughly 20% more oil volume in order to adequately fire the injector without loss of pressure.

Hybrid Injectors:

Hybrid injectors use a combination of components from both "A/B Code" and "BD Code" injectors. Utilizing the 7.1mm plunger and barrel of the "BD Code" injectors with the intensifier piston of the "A/B Code" injectors produces a 5.078:1 multiplication in pressure. On a system running 3,000 PSI of ICP, the pressure of the injected fuel will be extremely low at only 15,234 PSI (not taking into account base cylinder pressure). This is almost 30% lower than a stock Power Stroke and requires significantly higher ICP pressure to achieve the same injected fuel pressure. However, because the intensifier piston hasn't changed, the HPOP should be able to supply the oil volume necessary in order to adequately fire the injector.

The problem with Hybrid injectors is that while the injectors are generally capable of injecting more fuel, they do so at the cost of fuel injection pressure which ultimately leads to poor fuel atomization and decreased combustion efficiency. On the surface, increasing ICP 40% to get the fuel injection pressure back to normal seems like a relatively simple solution, but there is another problem. The firing oil control mechanisms in the injector (the poppet valve) has a seat pressure of usually around 3300 to 3500 PSI. Raising the pressure of the high pressure oil system can result in the poppet valve floating and causing the injector to not fire properly. For reasons outside the scope of this document, increasing the seat pressure is not a feasible solution and can ultimately will cause the injector to not fire at all.

Because of the issues with injection pressure when running hybrid injectors, we do not recommend these injectors for most "daily driver" street applications, opting instead to go with one of the more popular "A Code" or "B Code" single shot injectors.

If you have any questions or would like pricing on injectors, please feel free to contact us at http://www.gopowerhungry.com or by phone at (678) 890-111.

Submitted 08/20/2009

Bill Cohron
Power Hungry Performance

From time to time, a programmer will trigger the Passive Anti-Theft System (PATS) on an Excursion, Lightning, Mustang, or other PATS equipped vehicles. This is caused by a loss of communication between the PCM and the PATS module which triggers the PATS module to go into "THEFT" mode and disable the PCM for a period of time. Some vehicles are more sensitive than others in regards to what triggers the PATS system with some vehicles triggering it during some sessions and not in others.

In the event that this does occur and the "THEFT" light is flashing, use the following procedure to restore vehicle functionality.

1. Turn the key to the "ON" position, but do not attempt to start the vehicle.
   
   
2. The "THEFT" light will begin flashing rapidly (twice a second). After about 60 seconds, the "THEFT" light will stop flashing rapidly and begin a sequence of slow flashes (usually 1 blink, followed by 6 blinks).
   
   
3. Turn the key to the "OFF" position and completely remove the key from the ignition and hold at least two feet away from the steering column for 30 seconds.
   
   
4. Insert the key and turn to the "ON" position. Wait for the normal engine checking procedure to take place. The "THEFT" light should no longer be flashing. At this point you should be able to start the vehicle.

Submitted 12/02/2009

Bill Cohron
Power Hungry Performance