Ultimate Induction with Electronic Fuel Injection

Since the dawn of the modern performance era, fuel injection has been regarded as the best and most efficient way to meter and deliver fuel to a thirsty motor. Modern EFI technology seems to have reached its zenith lately, as aftermarket suppliers have finally begun to produce their own stand-alone, computer-controlled injection systems that can be adapted for use in just about any vehicle, providing an excellent balance of economy and power. The only drawbacks with most of these cutting-edge systems is that they require a laptop and moderate computer knowledge to set up, and they all look quite high-tech, which can be a real problem for those of us who worship at the flamed alter of vintage cool. A massive chasm has been forming over the past decade, and it divides the two camps of our hobby: street rodders and hot rodders. As street rodders rush toward the future with sleek restyled bodylines and computer-controlled motors, all but hidden from view by painted and sculpted engine shrouds, the hot rod contingent continues to travel back in time, reliving the past with raspy flatheads, percolating Strombergs, and burning bias-plies. While both sides of the rodding coin are cool on their own, Chico Kodama and his crew at Mooneyes have managed to build a bridge between the two mindsets, combining the look of vintage Stromberg 97 carburetion with the performance, reliability, and efficiency of modern EFI. By now you've probably already seen one of these amazing setups in past pages of R&C or at a show near you (NSRA named Moonjection the Best New Street Rod Product for 2003). The plan this month is to take a closer look at what goes in to one of these new/old school injection systems, as well as how to properly install one.

WHAT YOU GET
One of the most daunting parts of setting up a normal EFI system on a street rod or hot rod is trying to locate and match all the parts necessary to build a properly functioning package. The beauty of Moon's new setup is that virtually every possible combination of parts and packages is available, from the basic Stromberg-look throttle-bodies, all the way to a complete package, including an intake manifold with the computer pre-programmed and ready to run. Heck, if you're willing to travel out to their Santa Fe Springs, California, facility, resident EFI expert Ken Ferrell will even do the installation himself, ensuring proper operation.

Speaking of throttle-bodies, why don't we get down to business and talk a little tech. The bodies themselves look just like standard Stromberg 97 carburetors, minus the fuel leaks and tarnished finish. Each unit is precision-cast then CNC-machined to aircraft tolerances. The air horn measures 2 5/8 inches, which allows it to use standard Stromberg air cleaners and scoops. Bosch-style fuel injectors are hidden in the float bowls, and the fuel inlet can be found in the stock location. Internal shafts and throttle-plates are brass, and normal 97-style linkages work perfectly with the throttle-bodies. Also included with the system are a high-pressure fuel pump, in-line fuel filter, custom computer with harness and programmable control module, and trick mixture control box. Depending on the application, complete ready-to-run systems are available including linkages and the intake manifold.

The beauty of this system is that the throttle-bodies will work on any intake that accepts three-bolt-style Stromberg or Holley carburetors, except, unlike a carbureted system, you can throw on as many throttle-bodies as possible and the motor will still run great without loading up or running rich. Why? Because unlike old-school systems where more carbs mean more fuel, a properly functioning EFI system determines how much fuel is necessary for the motor at any given time based on engine speed and a variety of other factors then supplies only as much gas as necessary. Therefore, even a mild 265 can be fitted with four, six, or even eight of these throttle-bodies and still run like a champ. Suddenly, all of those cool-looking but totally impractical old intake manifolds floating around eBay have become viable hot rod gear once more.

HOW IT WORKS
While most fuel injection systems on the market today offer some form of stand-alone computer and operating software, Moon's is the only one available that does not require a laptop for fine-tuning. Instead, an EM-4 onboard brain measures air temperature, water temperature, manifold pressure (vacuum), throttle position (throttle position sensors, or TPS, are located on each throttle-body), and rpm. The computer then determines how long the injectors should remain open before triggering an electronic pulse which is fed to each individual injector and determines the quantity of fuel to be sprayed into the airstream. According to Moon, the manifold pressure or throttle position value multiplied by the rpm of the engine determines the primary pulse width, or how long the injector will remain open.

Unlike a standard carbureted fuel system, which requires only about 4-6 pounds of fuel pressure and a single (supply) fuel line, electronic fuel injection requires a much more precise mode of fuel delivery. In order to ensure a stable fuel supply, a large supply line constructed of high-pressure hose or hard line should run from the tank to the engine, with a smaller low-pressure line providing a return route for unused fuel. This allows the system to circulate constantly, which not only stabilizes it but prevents vapor lock, as well. After leaving the tank, fuel should run through a pre-filter to catch sediment from the tank, then through the high-pressure electric pump, through a secondary EFI-style filter, and through the fuel block that supplies the throttle bodies. Excess or unused fuel then runs into the regulator, which controls pressure for the entire system, and into a return line back into the tank. Optimal pressure for this system is 45 psi.

Once the fuel system is complete, the rest of the Moon EFI package is pretty basic. The onboard computer has harnesses that attach to supplied sensors, including air and fuel temperature sending units that go in the intake manifold, a vacuum/map sensor that attaches to the carburetor base or intake manifold, a throttle position sensor that hooks up to one of the throttle bodies, a tach signal wire that runs to the distributor, and of course power and ground wires to supply the necessary juice. Since every setup is a custom application, Moon supplies each ECU with a pre-loaded software package designed to work with your engine, and it should start on the first try if everything is hooked up correctly. Fine-tuning then involves utilizing the supplied mixture knob and LCD programmer to adjust the fuel curve as the car runs through its powerband in various driving conditions. This is best done on an engine or chassis dyno, but real-world tweaking also works (and is much more fun). Just watch out for John Law as you dial-in your powerband for maximum tire-smoking power.

INSTALLATION
Not happy to simply hear Mooneyes head honcho Chico Kodama talk the big game about his company's newest speed gear, we wanted to test it out for ourselves. After all, what kind of intrepid rod journalists would we be if we didn't give you, the reader, a first-hand account of whether this baby really works the way it's supposed to? After much bantering among staffers, it was decided that the donor car would be the author's recently completed Real Hot Rods Model A Lakes Modified. The little copper roadster has a traditional '40s look and feel, even though there isn't a single solitary vintage part on the car, which makes it the perfect candidate for this split-personality fuel injection. Of course there's always a fly in the ointment, and in this case it's the set of Vortec cylinder heads that came standard on the GM Performance Parts crate motor we installed in the roadster several months ago. Unfortunately, the General's new cylinder head design is incompatible with older-style intakes, which ruled out most of the trick vintage Tri-power and six-two-barrel intakes on which the Moon throttle-bodies look best.

Luckily, Moon's head EFI guru Ken Ferrell came up with a nifty solution. He fabricated a low-profile adapter plate that bolts to the top of the four-barrel intake manifold then spreads out and allows the installation of three Moon injectors. We get the look of vintage Tri-power with the reliability of a modern crate motor. While the adapter in this article is the first of its kind, by the time you read this Moon should have them in production and ready to bolt onto just about anything that takes a four-barrel.

After an intense six-hour thrash to get things bolted up and dialed-in, we had the new EFI working perfectly, and the roadster was driven home under its own power. After a few hours of driving and tuning, the motor ran better than it ever did with the standard four-barrel, as the injection provided snappier throttle response and more bottom-end torque. The trio of shiny new "Stromberg" throttle-bodies fitted with a vintage-looking fuel line and chrome-plated clamshell air scoops really shines when the hood comes off, as the little Bow Tie mill has been totally transformed from standard crate motor fare into a one-off vintage speed powerplant.

In case you couldn't tell, we're more than impressed with this latest technological triumph. Moon fully deserves their Best New Street Rod Product accolade, which proves that the rodding aftermarket is only getting more innovative and creative as the years pass. We just can't wait to see six or eight of these babies on a blown baby Hemi or nailhead Buick. If you build it, our cameras will come!