Muscle Mustangs & Fast Fords
The Four-Valve Swap Power Struggle Upgrade Part 2
Our Quest For Reliable 9-Second Timeslips From Our Modular Powerplant Continues.
Our concern with this arrangement was there was no flow through the fuel rails other than what was consumed by the injectors, which could cause a lean condition on the front injectors, especially if they drained the rails. We kept very close watch by reading the spark plugs on the front two cylinders after we had everything up and running. To date, we've seen no detrimental effects from this arrangement. This rear feed arrangement also located all of the fuel lines on the back of the motor and out of sight, cleaning up an already busy engine compartment, and again helping to maintain the OEM looks we after.
With the fuel system now sorted out, our attention turned to the fuel injectors. We expected that the potential power output of the supercharged Four-Valve motor could quite possibly suck the injectors dry, and at the time this was written, we were unaware of the RC Engineering 70-lb/hr units that we recently used in our '03 Terminator buildup. That being the case, car-owner Bob Watson spent a bit of time chatting with the folks at Acceleronics, who convinced him that the company's 95-lb/hr low-impedance injectors were the way to go.
We were skeptical of putting such large injectors in a car that was to be street driven, feeling idle and driveability would be compromised. The folks at Acceleronics explained that larger injectors, with larger internal discs that are controlled by the VersaFueler injector driver, actually provide better drivability. This is due to the peak-and-hold control scheme used with low-impedance injectors as opposed to the saturation scheme utilized on high-impedance injectors and OEM computers. Further discussion on this topic is beyond the scope of this article, but we did find that the 95-lb/hr injectors using the peak and hold control scheme gave the car better idle and driveability than the previously OEM-controlled, 60-lb/hr high-impedance injectors used on the previous Two-Valve motor.
While the Acceleronics injectors drop right in place of the factory pieces, there is a bit of rewiring needed to hook up the VersaFueler to the injectors. The injectors were coupled to the wiring harness with the familiar Cobra injector-conversion adaptors. We found that the VersaFueler unit fit neatly on the firewall near the heater core tubing.
Installation of the VersaFueler is very simple. The controller has two plugs with lengthy wires extending from each of them. These wires are routed to each positive injector wire. There is an input and an output plug from the VersaFueler, and each plug has the same arrangement of wire colors so you don't confuse cylinder inputs and outputs. You then cut the positive wire of each injector connection and connect the VersaFueler input wire to the injector wire coming from the EEC. Then connect the same color output wire from the VersaFueler to the wire going to the injector. Hook up the 12-volt supply and the ground and you're done.
The driver senses when that injector is called to fire and for how long; It then converts the saturated control scheme to a peak-and-hold scheme and operates the larger low-impedance injector accordingly. The EEC never knows it's there, and it doesn't affect the tuning. You may also use the VersaFueler unit to improve control of high-impedance injectors. So if you have some large injectors in place with idle or drivability problems, this unit could solve the problems without replacing your existing injectors. There are aftermarket engine management systems available that will drive large low-impedance injectors. These work well but compromise the benefits of using the stock Ford EEC to control all engine, transmission, and other vehicle functions. It also adds additional complications to the tuning process.