Often a racer pushes his/her performance beyond what they originally plan to. How far can one go on a stock computer and electronics? The answer is fairly simple.
Answer these 3 questions: 

• How fast do you want to go?
• What injectors will it take to support the horsepower needed to go that fast?
• How often is the car driven on the street? 

Computer chips 
In today’s performance world, aftermarket electronics can come in a simple form such as a computer chip. Mike Wesley’s Autologic software has taken the limitation of what one can do with a factory computer to jaw dropping limits. With the 1986-1995 Ford Computers (aka EEC IV), cars have been able to run in the 8 second time zone! Naturally the chip isn’t doing the job itself, big cubic inches, high boost, and the right engine parts are needed as well. However a simple computer chip, along with the right tuner, can give enough control to produce great results. 1996 and up Ford’s are a little different in what they can do. The factory computer (aka EEC V) is much more complex and sophisticated. These computers are state of the art computers and can be harder to crack. As it stands right now, the biggest limitation for the EEC V computer is driver control. Most tuners can now turn off all the OBDII controls for the more modified combinations. Many aftermarket companies have come up with ways of tricking the Ford EEC V computer like the MIL eliminators, and IMRC connectors. Other people like Sean Hyland and Pauls High Performance use Superchips, and have gotten some very impressive results as well. New on the block is Diablo Sport, another chip manufacturer. Not enough test data is available yet on the Diablo to give a comparison against the other brands. 

Injector drivers 
When you need to run big injectors (72,83,96) they come only available as low impedance injectors (See October's tech article for more info on injectors) Running low impedance injectors with a factory computer can/will cause harm to the stock electronics and most likely cause a hardware failure. The cure for this is to run different drivers in conjunction with the stock computer. For EEC IV computers Pro M was the first to make it possible to run different drivers via an injector driver box. This box was a simple plug in box to the factory fuel injection wiring harness. Now, tuners can go into the stock computer and modify the inside brains so that the computer will not blow up. For EEC V computers, there aren’t many options. A 5.0 Pro Mod box can be wired into the stock injection wiring, however these boxes are extremely hard to come by these days. Pro M wants a small fortune for them new now, and they are hard to find used. For now the only option is going with a stand alone computer. Mike Wesley and Jimmy LaRocca are in the process of coming up with a fix to this. Stay tuned. Most stand alone computers (see below) have the option to run either high or low impedance injectors. 

Reputable chip tuners
Mike Wesley is widely regarded as the best chip tuner in the country. Of course who better to know the Autologic software than the man that designed it. Other reputable tuners are Chris Johnson @ JMS Motorsports, Jim LaRocca, Lideo Iacabelli @ Alternative Auto, Joe Mainero @ UPR, Byron @ R.A.C.E. Systems, Pauls High Performance, Sean Hyland, and Powertrain technologies. 

Open versus Closed loop
An open loop condition is when the computer takes the fixed settings in the computers tuning program to adjust a vehicles air to fuel ratio. Closed loop is when the computer takes the feedback from the 02 sensor to correct or change the air to fuel ratio as needed. The factory stock Ford computers (EEC IV and V) both use open loop only at WOT. Most speed density stand alone systems give you the choice of using either style. There are 2 schools of thought on open loop versus closed. Many racers like Jim Summers use the 02 sensor feedback to adjust air to fuel ratio’s. Some racers like Jim LaRocca don’t like using an 02 sensor for feedback, especially when running leaded gas as the lead can ruin the calibration on the sensor thus giving false feedback to the computer. The fear is that a false rich condition can cause the computer to incorrectly remove fuel from the calibration of the tuneup, thus harming the engine from detonation. Other tuners feel that giving 02 sensors control to only add fuel fixes the lean fear and works just fine. 

Stand Alone Computers
Aftermarket engine management control has been around since the late 80’s. It started out in a primitive form like the Ford Motorsport extender, early DFI, and piggy back interceptor. Stand-alone computers eliminate the stock computer and wiring harness. It has its own hardware such as computer and wiring harness. Most engine management systems are speed density systems and eliminate the use of mass air sensors. (more on that later). A lap top computer is needed to program and tune the parameters of the car (spark & fuel). 

Advantages 
Advantages of a stand-alone computer are that you can custom tune your car anytime you want or need to make changes to it. With a computer chip, your tuning parameters are preset from your tuner and make it impossible to change parameters on the fly. With stand-alone computers you can also run any type of injector and not worry about the computer electronics blowing up. Another great feature about stand alones are their ability to datalog. Datalogging is very important especially in drag racing when you need to see your car’s performance down the track. A driver can’t keep is eyes glued to one gauge down the track, alone 10 of them. Stand alones can datalog air/fuel ratio, RPM, spark, coolant temp, injector duty cycle, 02 correction, boost pressure, and many more functions. All keys that are critical to tuning. Another advantage of a stand-alone computer system in a lot of systems is the ability to be able to run closed loop at WOT. By running closed loop at wide open throttle, you can use the feedback of the wide band 02 sensor to automatically correct air to fuel ratio. 

Disadvantages 
Running speed density does have their disadvantages. Speed Density systems equipped with aftermarket cams and big fuel systems can never run as smooth as a mass air system can on the street, thus streetability can suffer to some extent. The difference of speed density and mass air systems are the measuring point of air. Speed Density systems use a map sensor to gauge how much air is going into the engine at any given RPM. A mass air sensor uses a heated element to determine the amount of mass airflow going into the engine. With the invention of a blow through type mass air flow Sensor, the restriction on the inlet is gone, and thus any advantage running speed density. 

Types of Standalones
DFI – The older style DFI are known for their reputation to be non user-unfriendly. This is a speed density system. DFI systems are harder to tune for the average person, and require a more experienced tuner to set up a car. The newer versions are said to be more user-friendly. DFI standalone's are not available for EEC V computers just yet, but they are available as piggybacks.. Job Spetter, and Ken Dutweiller are regarded as two of the premiere tuners in the country. 

EPEC – A Mass air flow system – Runs in open loop only.. Advantages: Automatically corrects air/fuel when it sees changes in air density. You don’t need to adjust the parameters as much, set it up and forget about it. Disadvantage: Harder to use and understand for people not experienced with it. Jim LaRocca is regarded as the premiere EPEC tuner in the country. New advantage is blow through mass air eliminates the air restriction of a normal suck through mass air. Available for 1986 and up Ford Mustangs. Soon to be available for 1999 and up 4.6's. 

Speed Pro – Speed Density system- Runs in open or closed loop at WOT. Advantages: User friendly and popular among inexperienced and experienced tuners. Disadvantage: Does not correct air/fuel for changes in air density. Monitoring the air conditions and correcting the calibration for it are vitally important. Available for 1986 and up Ford Mustangs. Jim Summers is regarded as one of the top Speed Pro tuners in the country. 

Motec – Speed Density System – Runs in open or closed loop at WOT. It also has the same advantages and disadvantages as the Speed Pro. Motec is a more complete kit than the Speed Pro and gives you more bells and whistles for more total control. Many people feel it is less user-friendly than SP, but is still user-friendly overall. Ken Dutweiller is regarded as one of the premiere Motec tuners in the country. 

Electromotive – Speed Density System – Runs in open or closed loop at WOT. Comes with its own ignition and coils. Electromotive is widely known for its complexity and lack of experienced tuners. Not an easy system to use. Datalogging is very poor. John Mihovetz is one of the premiere electromotive tuners in the country. 

Anderson PMS – Piggyback controller, not a stand alone. Controls timing, fuel, boost, rev-limit, nitrous, 2 smart switches & 3 selectable programs. For EEC IV cars only and it can come with low impedance injector drivers. I’ve seen this unit used in many low 10 second cars and a few 9 second cars. Not as much control as a stand alone but much better than having just a chip. An additional box is needed to datalog. Cost is very reasonable, and is only slightly higher than just a chip. 

Which is the right choice for me?
If you want to retain your cars every day streetibility there are limiting factors that you will run in to, injector size is one of the them. Retaining a mass air flow sensor is important for an every day street car. As you push more power into your engine you will find that it will be harder and harder to retain good streetibility. Larger injectors, big fuel pumps, high octane, stand-alone computers, and race transmissions will all be in the cards down the road for race car power. The desire for race car power in a street car will require compromises. The best thing to do is write out a list of goals you wish to achieve, and see what it takes to achieve them. See what aspects of your goals are not so important. Many people don’t realize the big picture until the big picture is already drawn. Plan ahead, ask experienced tuners, racers, and talk to your friends.

Dave King