Fuel Injection Conversion
Last time around ("Fuel Injection Conversions," Dec. '08 Modified Mustangs & Fords) we looked at some of the history and background of fuel injection in modern engines. There are many benefits versus carburetion, and these can include improved performance, both as higher horsepower and torque, better gas mileage, easier starting, and the potential for reduced emissions.
When dealing with an older Mustang, making the switch to fuel injection involves more than just swapping engines or adding aftermarket EFI induction parts. There's a variety of sensors to be changed, along with their associated wiring, and you'd better bring along the ECU (electronic control unit, aka "computer") or your new installation is going to be brain dead.
Beyond this, there are extra considerations if you are going to add a blower, change cams, or get into other performance enhancements. Some generations of ECU are not easy to reprogram, nor do they like adapting to the changes you want to make. Still, if you do your research, you will find the appropriate shopping list of parts to do the job. It is probably going to take time to get them all, shopping around the Internet and local swap meets.
A Better Way
However, if you want to get going right this minute, there are commercial fuel-injection kits that you can pick up and install. If you have to keep the "lefty-loosey, righty-tighty" thing in your mind while working on cars, you should probably enlist the help of a good shop to do the conversion for you.
The single biggest benefit of using a commercial kit, such as the FAST XFI Electronic Fuel Injection we're going to work with today, is that everything you need comes all in one package. There is no need to go looking for this little bit or that other piece. You get it all in a kit that is designed for your particular engine.
To get our education underway, we're going to hang with the guys at Westech Performance Group in Mira Loma, California. These guys know horsepower and they have the dyno facilities to back it up, whether the motor is in or out of the car. One of the more interesting things about using an engine dyno, like the Superflow 900-series units these guys have, is the extra information you can get. This includes airflow, air fuel ratio, exhaust gas temperatures, fuel flow, spark curves and BSFC (brake specific fuel consumption).
Remember what we talked about that last time? BSFC is a key piece of information to check for appropriate sizing of your fuel injectors. There are "rule of thumb" numbers and there are real numbers, if you can get them. This kind of engine dyno tells you exactly what the real number is.
For our hands-on work, we'll be using a 302ci small-block engine, but the XFI installation steps are just the same, whether it's a Windsor, an FE, or a Cleveland. Let's get started.
Here is what you get when...
Here is what you get when you open the XFI Fuel Injection Kit. It is plenty to keep you busy for an afternoon. Aside from a new intake manifold, you get a new distributor, a properly sized set of fuel injectors, fuel rails, a new throttle body, the FAST XFI controller and tuning software, oxygen sensor, and professional-grade wiring harnesses that use OEM-level connectors for reliability and durability.
Our small-block is sitting...
Our small-block is sitting on the dyno stand while being torn down. These guys are fast, so getting ready only takes a few minutes. Here, the old intake comes off to get ready for the shiny, new EFI-ready version.
If your mama told you that...
If your mama told you that cleanliness was next to godliness, she surely had this job in mind. Getting rid of old gasket and sealer materials is important because the new parts have to fit and seal properly. If there is a vacuum leak, you'll have trouble with driveability. If there's a coolant leak . . . well, let's just say that you don't want to deal with coolant in the oil.
Silicone sealer has been used...
Silicone sealer has been used to help the gasket seal around this coolant passage, as well as across the valley to the other head. All of this needs to be removed, preferably without scratching or damaging those nicely machined surfaces or getting the old gasket bits into any of the engine's passages (crumpled up newspaper is a simple way to block off the ports).
After applying some fresh...
After applying some fresh silicone sealant around the coolant passages and across the valley, we can start putting things back together. Here, the composite manifold gaskets are laid in place and lined up.
You'll need to apply a good-sized...
You'll need to apply a good-sized bead of silicone sealer across the valley walls. Be sure to use an automotive grade that is safe for use with oxygen sensors.
With that prep work complete,...
With that prep work complete, it is time to drop the new intake in place.
We have to run down the fasteners...
We have to run down the fasteners to finger tight first, then use a torque wrench to tighten the bolts. A patterned sequence of tightening is used to prevent any possibility of warping the sealing surfaces. You can also see the empty ports, waiting for the individual injectors to be installed.
Next, the injectors and fuel...
Next, the injectors and fuel rails are installed. The rails are fastened to supports on the intake manifold. You don't want anything coming loose here!
Braided lines with AN fittings...
Braided lines with AN fittings are used to connect the rails to each other and to a fuel supply.
The throttle body gets additional...
The throttle body gets additional reporting abilities from installing a throttle position sensor (TPS) and the idle air control (IAC) valve. This gives the XFI a means to control and maintain the engine idle speed under varying temperatures and conditions.
Here is the Manifold Absolute...
Here is the Manifold Absolute Pressure (MAP) sensor. The MAP sensor tells the ECU what the manifold pressure is, which varies with load.
Moving on, it's now time to...
Moving on, it's now time to install the distributor. First, a little assembly lube is applied to the distributor gear, which is driven from the camshaft.
The techs move the crankshaft...
The techs move the crankshaft around to TDC, or top dead center, on the number-one cylinder. Without doing this, you can mistakenly install the distributor out of phase and nothing will run, since your spark timing will be off.
Now the distributor can be...
Now the distributor can be put in place with confidence.
Final position adjustment...
Final position adjustment of the distributor is decided by a built-in LED that confirms the crankshaft sensor signal.
With that work complete, the...
With that work complete, the distributor assembly can be finished and the spark-plug wires installed.
The wiring for the individual...
The wiring for the individual fuel injectors needs to be hooked up, of course, and the included harness simply lays on the intake and the labeled connections are made to the injectors and surrounding sensors.
The last of the connections...
The last of the connections to be made brings everything to the XFI controller box. We're just about ready to get started, but first. we need to get the laptop talking to the XFI System for some initial setup.
With the engine in the dyno...
With the engine in the dyno cell and running, finer tuning can proceed. It's always best to start with the basics of fuel and spark maps.
Before long, a 3D map emerges...
Before long, a 3D map emerges showing spark advance versus manifold pressure and engine rpm.
With other settings in a safe...
With other settings in a safe range, it's time to make a full dyno pull, here to just over 6,100 rpm. BSFC is showing as 0.532, which is about 5 percent higher than our rule of thumb for normally aspirated engines. The results: 462 flywheel horsepower and 475 lb-ft of torque! This will make any midsize Ford a true blast on the street or the track.