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Professional Products’ Powerjection III

Written by  Scott Hayes

Just bolt it on and drive away, how simple is that?

By Scott Hayes

Photography by: Jim Vaughn

Aftermarket fuel injection systems have been around for a number of years. The first units appeared in the mid-‘80’s, but despite the fact that a number of companies have developed EFI systems, they have never enjoyed the popularity that everyone expected. Early systems were rife with bugs, and these problems no doubt turned a lot of people off to the idea of buying and installing an aftermarket EFI setup.

Over the years some of these systems have been vastly improved, with the majority of the glitches worked out. But the high cost of most systems, coupled with the need for expert laptop tuning, has again kept them from being at the top of most performance enthusiasts’ list of parts to buy. Another barrier was the time and the complexity required to install a complete system.

Now Professional Products has the Powerjection III EFI System that was specifically designed and engineered to overcome the pesky problems plaguing aftermarket EFI. It’s simple to install and self-learning!

First, they addressed the cost. The typical over-the-counter retail cost of a Powerjection III system can be as little as $1,815, and this includes everything required. The only possible option would be a P3 Fuel Delivery & Return Kit for about $242. This kit includes enough -06AN stainless braided hose, hose ends, and fittings to plumb both an inlet fuel line and a return line for most cars.

Cost reduction is achieved through several methods. The company elected to go with a throttle body style system, which eliminates the need for an expensive manifold and fuel rails. Since one of the most expensive components in a system is the injector, going from eight to four injectors substantially reduced the cost. They miniaturized the computer (which Professional Products calls an EMS for Engine Management System) and then cleverly mounted it directly on the throttle body. This eliminated 90% of the wire harnessing and connections involved, which further reduced costs.

Many of these cost reduction measures also contributed to the ease of installation. Eliminating the need for a manifold swap and depending on certain factors, such as the vehicle that the unit is being installed on, a complete install can be done in as little as three or four hours. An experienced mechanic can do it in two.

We decided to see for ourselves just how easy an installation might be, plus what kind of performance and/or economy gains can be achieved. The car we found as our vehicle turned out to be the ideal choice, as it was representative of what a lot of readers either has or can relate to. The Powerjection III is ideally designed to swap out a Holley 4150 or similar square bore carb. It has exterior dimensions nearly identical to a Holley, has the exact same linkage arms and will allow the use of a stock air cleaner.

The vehicle is a 1970 Chevy El Camino SS 396 with cowl induction.  The vehicle had a spread bore carb, which created a few additional challenges but nothing that wasn’t easily handled. The El Camino had a few modifications such as a street performance aftermarket manifold, an Edelbrock 650 cfm carburetor, a Crower street cam with 276-degrees duration and .518-inch lift, plus headers.

The Powerjection III comes with self-learning software installed into the system that is suitable for the vast majority of vehicles. That means you can take the car out for a spin and it will essentially self-tune itself for optimum performance. Only engines with radical modifications will need laptop tuning, and even in that case, the Powerjection III is much simpler than other systems. Connect a laptop to the EMS, load in the Dashboard Software and let the Wizard go to work. The Wizard will ask you to enter a few key bits of info, such as estimated maximum torque, manifold type and camshaft type. Once this is done, hit the enter key and the Wizard designs a new map for you. Or, if that’s not close enough for you, you can go in and individually do any type of programming or mapping exactly the same as you would with any other aftermarket EFI system.

After the installation is complete, turn on the electric fuel pump and check every single fuel line connection to make sure there are no leaks. Once you are confident there are no leaks, it’s time to start it up. In the case of our El Camino, it immediately fired but needed a slight screwdriver idle adjustment. Check the fuel pressure on the supplied fuel pressure regulator. Recommended pressure is 43-PSI. If your reading is different, adjust it to the proper pressure. After driving the vehicle for 20/30 minutes the self-learning software will have your engine purring and ready to run hard.

How did this installation turn out? By anyone’s standards it was an unqualified success. First, even working around two photographers who slowed the progress at each step, and the additional issues that slowed things down because of the spread bore carb; the entire installation was about four hours. If we had used a vehicle with a Holley carb and taken no photos, it would have been a three-hour or less project.

Prior to the installation we took the car to W.O.T. Performance Products in Riverside, CA, to have it run on their chassis dyno. After the installation was complete, and enough driving was done to have the adaptive learning feature work its magic, we took it back for a follow-up dyno test. Here are the results:

  • Peak to peak torque was improved by 9 lbs. ft. It went from 281 to 290 lbs. ft. OK, that doesn’t sound like much, but peak numbers do not tell the whole story. Average torque from roughly 2,500 to 5,000 rpm improved by 14 lbs. ft., and at 4,200 rpm it was a whopping 25 lbs. ft. better.
  • Peak horsepower took a major leap from 211 at about 4,700 rpm, to 238 at about 4,900 rpm, a 27 hp gain. Average horsepower gain over the full pull was 16 horsepower. Best of all, while the power nosed over with the carb at 4,700, it was still going up at 5,000 with the Powerjection III.
  • While the car was on the dyno after the EFI installation, we dropped the total timing from 38-degrees to 32-degrees. This made a slight improvement in peak power of one horsepower going to 239, but peak torque jumped an impressive 24 lbs. ft. to 314.

The net result of this is that although peak power didn’t change much, power was up significantly all the way up through the rpm range. Before the timing change, at 3000 rpm there was almost no difference before and after the EFI change. After the timing was reduced, horsepower increased by 16 horsepower at 3,000. At 3,800 the difference was about 5 horsepower and after the timing change the difference was about 18 horsepower.

Unfortunately, we didn’t run the car with the carburetor at the lower timing setting so there is no direct comparison to see if the car would have shown these same differences. David Berg, the owner of the El Camino, reported that all around drivability and throttle response was dramatically improved. The car even started better than before and of course there will be no more choke issues on cold mornings. David said it is like driving a totally different car and the amount of improvement is way beyond his wildest expectations.


Professional Products

12705 S. Van Ness Avenue

Hawthorne, CA 90250



W.O.T. Performance Products

12321 Sampson Avenue, Unit N

Riverside, CA 92503


Here is the complete Powerjection III system. Compared to other aftermarket EFI systems it looks like a lot of parts are missing, but this is the complete kit and everything needed for installation is here.

This is the optional #70107 P3 Fuel Delivery and Return Kit. Our El Camino is factory equipped with a fuel return line so we didn’t need to use this kit. Yes, even though this vehicle is carbureted, it did come from the factory with a fuel return line from the fuel pump back to the fuel tank.

The first step was installing the supplied EFI Fuel Pump, which comes with a trick-mounting bracket that also doubles as a heat sink. The pump was mounted to a stamped steel cross member next to the gas tank using self-tapping sheet metal screws. The pump is spliced in between the tank and the factory fuel line going to the engine.

The next step was installing the O2 sensor. The boys at the EFI division of Professional Products came up with a really simple way to do this. No welding! Just drill a 5/8-inch hole in the exhaust pipe 6-to-12 inches back from where the head pipes come together.

Thread the O2 sensor into the bung and then clamp it to the pipe with the supplied high temperature gasket and the two supplied stainless hose clamps.

Remove the air cleaner, disconnect the linkage, and unbolt the stock carburetor.

Because this was a spread bore manifold we used an inexpensive Professional Products adapter plate (#52111) to accept the Powerjection III throttle body. Install the supplied ¼-inch thick gasket and heat isolation spacer and then install the throttle body.

The throttle body has a few wires that come out of the EMS. One goes to either the negative side of the coil, or if an MSD unit is used, it goes to the tach sender terminal on the MSD box. Another wire goes to the ignition switch; one goes all the way back to the fuel pump, and the final one connects to a 12V power source. No ground is required as the unit is self-grounding once it is bolted to the manifold.

On this installation, the pipe threads on the supplied temperature sender were smaller than the pipe tap in the manifold so a pipe thread reducer was required. It is best to screw the sender into the reducer, using some thread sealant, and then screw the assembly into the manifold. If you act fast only a minor amount of coolant will be lost which can easily be topped off. This avoids having to drain the coolant. Connect the lead from the EMS to the temperature sensor.

Thread the O2 sensor lead from the throttle body down to where the sensor is installed into the exhaust pipe and click the two connectors together. If you have any excess wire, tie-wrap it to keep it away from the exhaust pipe or any moving components.

Connect the throttle cable to the throttle body linkage. Because this was a spread bore setup, in order to connect the stock throttle linkage, one of the holes in the throttle body linkage arm had to be enlarged with a drill.

The stock mechanical fuel pump is unbolted from the engine and a fuel pump block off plate is installed. Remove both the inlet and return fuel lines from the pump before unbolting it.

The supplied fuel filter is then spliced into the fuel delivery line from the tank and a short piece of hose is needed to connect the filter to the inlet fitting of the throttle body.

Another section of hose runs from the fitting on the bottom of the pressure regulator down to the return hose that was disconnected from the stock fuel pump. The installation is now complete.

Here is an array of Powerjection III systems in various stages of assembly. While the throttle body is manufactured offshore, all the electronics, final assembly, and testing is done in the Professional Products EFI facility in Hawthorne, CA.

This is one of two stationary engines used for testing each assembled Powerjection III system. Each unit is bolted on an engine and run with a laptop connected to check that all aspects of the system are functioning correctly. This stationary test stand sits outside but can be run inside the shop during inclement weather.

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