5.0 Mustang & Super FordsProject Vehicles
Project Mondo Stocker Part II: Digital Fuel Injection
Accel's Stand-Alone Fuel Injection System for the Masses
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There's a certain mystique surrounding Accel's Digital Fuel Injection (DFI) system. When first introduced in the '80s, only the really high-tech racers with money to burn dared try a stand-alone fuel injection system. Without solid tuning experience, it was easier to do more harm than good with the system. After all, the DFI takes the tuning away from the conventional fuel pressure regulator and timing light and puts it in the hands of whomever is at the laptop. But, as time wore on and more and more racers demonstrated the benefits of this incredible tuning aid, it became a viable alternative for those who are ready to take their 5.0 Mustang to the next level.
When we first considered the buildup of a serious supercharged 5.0 (See sidebar "Project Mondo Stocker Setup"), we knew that we would eventually be talking about an aftermarket engine control system. For the money, the DFI system is a great choice for those who want anything more exciting than a hot street car. If you want to go into the 10s or faster with a blown and injected 5.0, you are going to need a host of aftermarket components, including a race fuel management unit ($300), boost timing retard($300), an accurate mass air sensor like a Pro-M 83mm unit ($400), some sort of device to control the air/fuel ratio--like the FMS Extender ($500), Anderson PMS ($750), or C&M Software-programmed chip ($200)--and perhaps some sort of secondary injector system ($350) to help control injector pulse-width with low-impedance injectors over 50 lb/hr. These last devices are also necessary if you want to operate the motor past the factory dictated 6,250 rpm limit. As you can tell, these are pricey items that can quickly shoot a hole in even a serious player's budget. But, with the DFI, you get a system that replaces all of the above mentioned parts and provides an infinite number of adjustments for tuning and expandability. Also, by making the MAS unnecessary, you effectively remove one of the major restrictions from the intake tract.
The benefits of the DFI are well documented. With a factory computer, Ford had to make several potential owners happy. As hard as it is for us to believe, there are some people who actually buy a 5.0 Mustang with no intention of making it faster. That forced Ford to design an ignition and fuel plan that would make a Mustang work in less than tuned-to-perfection condition. Also, production variances make it nearly impossible to optimize a computer setup for every car. Besides that, Ford designed a computer program that had to take into account that the motor might not be fed high-octane gas at every fill up or have a brand new set of ignition components every 1,000 miles. Basically, the EEC IV has to guess what the right strategy is to make the motor work to its fullest potential. And, it does a great job, but the DFI can do it better.
When a 5.0 gearhead replaces the factory stuff with the DFI package, the tune can be custom-designed to that specific motor, for that one purpose. And, in our case, that purpose is maximizing the horsepower and torque that reach the pavement by way of 28x10.5 Mickeys.
You're probably wondering why we haven't included all of those groovy screen shots that have become considered mandatory with tech features on the DFI. There are two reasons. First, the programming wasn't done on our 5.0 at the time the installation story shown here was shot because we are constantly adding more parts to the project. This time we told Jim Summers to install it with the GT-40, but while we were at ASSC, Mike Hally at Hi-Flow Heads was whittling away on a truck lower to mate with a box upper we had acquired. So, as soon as the hand grenade--uh, motor--is reassembled, we'll be back with an in-depth feature on just the programming aspects of the DFI. Second, we have heard horror stories about readers putting Grand National programs on a nitrous-assisted 5.0 just because they saw the maps in a magazine, and tossed the cookies of an otherwise-nice piece. It is one of those things that can really get you in trouble, and we're not going to put our readers in jeopardy.
To get you started, most dealers will provide a base program preinstalled on the processor (it comes from ACCEL with no programming). If not, whatever shop you choose for a final program should be able to send you something they call a limp program just to make the car run without getting into trouble. This will allow you to get the car to the shop for final tuning.
As we've talked to more and more users of DFI, we've become believers in both the quality of the product and the skills of the tuners who use it. As their experience continues to grow with the more common 5.0 Mustang combinations, DFI becomes a more viable choice for those who thought that it was once an option for only the elite.
For these reasons, we had noted DFI expert, Jim Summers of ASSC, install a complete DFI system with the optional injector driver on Project Mondo Stocker. In the experienced hands of the ASSC staff, the installation went smoothly and took about three hours to get the harness and all sensors installed. Finishing touches and programming will take a little bit longer.