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Car Craft’s Giant EFI Test

We Test Four Self-Learning Throttle-Body EFI Systems on a Rat-Motor Nova

By , Photography by Ed Taylor

We've seen several ideas over the years for in-tank electric pumps and most of these are good systems, including the Rick's Tanks version we are using in our Nova. But, as in the Rick's Tanks case, it requires the use of a custom and sometimes stainless steel tank that can be expensive. In 2012, Steve Matusek, president and owner of Aeromotive, introduced the Phantom fuel-delivery system. This system uses a highly efficient turbine pump located on a stand that positions it just above the floor of your existing fuel tank and returns the fuel to the same location. The pump is surrounded by fuel cell foam with a small plastic bucket at the bottom that retains fuel around the pump. This is by far the most efficient, compact, and affordable fuel-delivery system idea we've ever seen. This is what you should use for a fuel-delivery system. Our recommendation is to purchase a basic TBI kit without the fuel-delivery system. Install the Phantom Aeromotive system and enjoy a trouble-free package.

An exception to this would be if you were going to max out the horsepower potential of the FAST EZ-EFI 2.0 at 1,200 hp. In that case, FAST offers a complete in-tank fuel pump kit (without a reservoir) under PN 307501 that FAST says will support as much as 1,900 naturally aspirated horsepower at 43 psi.

We've installed the Phantom system in a '65 El Camino in a previous story ("The Phantom Knows," Oct. '13) fitted with an EZ-EFI I TBI and tested the system by pushing the fuel level down to less than two gallons and experienced no surging or fuel-delivery hiccups. You should be able to sit on a hill with the engine idling with barely a couple of gallons of gas and not worry about the engine dying due to lack of fuel. That would be impossible with a stock tank using an external EFI pump because the fuel pickup would be sucking air. The Aeromotive Phantom system (PN 18688, $549.97, Summit Racing) is capable of delivering 340 liters per hour, equating to 90 gallons per hour, which Aeromotive conservatively rates at 825 EFI normally aspirated horsepower. This is more than enough fuel to feed any of the systems we've tested, except perhaps the EZ-EFI 2.0's at maximum horsepower potential. We'd also recommend a return-style regulator to complete the fuel-delivery system. We've built many EFI systems over the years and evaluated many others. The Phantom is the best EFI fuel-delivery system for a muscle car that we've ever seen. If you don't have the money to spend on a good fuel-delivery system, then you should ask yourself why you are spending $2,000 on EFI only to cheap out on the most critical component in the entire system. There's a reason that the OE companies all use in-tank fuel pumps for their cars. You should, too.

Configuring the ECU

Each EFI system requires specific inputs to configure the ECU to your particular application. These processes are usually called Calibration Wizard or Setup Wizard. The process follows a similar path—just not in this exact order. The first input is generally engine displacement. In our case, we input 496 ci. All but the EZ-EFI 2.0 also want a camshaft input. Some are more specific than others, but most rank the cam based on intake lobe duration numbers generally in categories of Stock, Mild, or Race. The Atomic system actually warns in the instructions that if the camshaft is more than 250 degrees of duration at 0.050, you shouldn't use this system. This is because intake manifold vacuum will be so low that the system would have difficulty working within those parameters. This is one reason why we chose to test these systems on our 496ci Nova, since our idle vacuum barely achieves 8 inches, which tends to tax the software design, as opposed to installing this system on a 350ci small-block with a mild cam that idles at 16 inches of manifold vacuum. After the camshaft, idle target rpm is another common input. This is essentially commanded idle speed. Keep in mind that if the IAC count on any of these systems is very low yet the engine speed is still too high, you may have to mechanically adjust the idle speed on the throttle body.

Rev limit is generally the next input these systems require. Because ignition control might not always be available, the systems use fuel shutoff to control engine speed. Keep in mind that this does not control mechanical engine over-speeds such as downshifting from Third to First at high speed. Some systems may also ask you the type of ignition you are using—either stock or capacitive discharge.

Other commands that you will need to set include the desired idle, cruise, and wide-open throttle (WOT) AFRs. We set our big-block up to idle at 13.9:1 with a similar air/fuel for cruise and a WOT AFR of 12.8:1. With these simple few inputs into the system, we were ready to rumble. If it sounds simple, it's only because it is.

Self-Tuning

The key feature of all these systems is what is called Self-Tuning. Let's use the commanded idle air/fuel ratio and idle speed as an example. To start, you command the speed you want the engine to idle and the AFR you want. Given the size of the engine, the injector size, the fuel pressure, the manifold pressure, and about a dozen other variables, the ECU estimates the amount of fuel required to deliver on those commands. The key is the feedback supplied by the WBO2 sensor. The oxygen sensor reports its readings to the ECU. The report will be that the AFR is either too lean, right on the money, or too rich. The ECU quickly computes the difference between commanded and actual and sends a new injector pulse width, and the process starts all over again. This is called closed-loop control. It only takes a short time for the ECU to narrow down the parameters, which is why it didn't take long for each of these systems to learn the basics necessary to make the engine run really well.

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