Why Put an EFI in Your Off-Road Vehicle?

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It may be a dirty sport, but modern fuel injection can take the punishment.

When racing out in the desert or simply crawling up the rocks of your favorite spot, Electronic Fuel Injection (EFI) can improve the drivability and reliability of your truck or rig. Even the idea of requiring a laptop and being able to read fuel maps are long past, but that’s not to say you can’t get improved performance when doing it. Let’s explore the original fuel injection method, the first start of EFI for the aftermarket and how modern EFI systems are as easy as plug-and-play.

Back in those early years of induction, the carburetor was where it was at. It took Bernoulli’s principal by introducing a venturi above the throttle plate. This increases the velocity of the air, drops the static pressure and creates a pressure differential to pull the fuel out of the float bowl. Of course, there are jets in there to determine the amount of fuel that comes out at open throttle, and the idle is controlled by the vacuum under the throttle valve at a pair of ports and is adjusted with a needle valve, but that’s the basic idea.

That would soon change, too, and not too far past the mechanical injection systems of Mercedes and Chevrolet. In 1957, Bendix developed the first ever Electronic Fuel Injection System, called it the Electrojector and placed it into the AMC Rambler Rebel’s 327-CI. This engine made 288 horsepower and produced peak torque 500-RPM - lower than a similar carbureted engine as it produced a cooler, denser air intake charge. However, this also meant the engine would only run well in warmer weather, so it was never offered to the public. In 1958, the system was tried once more in the Chrysler 300D, DeSoto Adventurer, Dodge D500 and Plymouth Fury, but just didn’t work out, and those vehicles would end up with four-barrel carburetors. Eventually, Bendix sold the patent to Bosch, who went on to create the D-Jetronic for the Volkswagen 1600TL/E 9n 1967.

Eventually, EFI would hit the aftermarket with the Accel, creating their first ever reprogrammable ECU that took the place of the OE system. While billed as “user accessible,” it required a computer to program, but it could work with four-, six-, or eight-cylinder engines from any manufacturer. It only controlled fuel injection, unlike modern standalone systems we see today, but this was still a huge jump in performance technology in the aftermarket industry.

Now we get into today’s EFI Systems and the technological leap we’ve seen since that Accel system and even more so over the original Bendix Electrojector. These systems can run everything the engine needs to run, from things as simple as just controlling the fuel for a TBI (throttle body injection) system to controlling camshaft phasing, spark, cam timing, fans, boost pressure control and anything else you could ever need.

Many of these systems work with OE engines, like the popular LS and the Ford Coyote, out of the box with wiring harnesses that are just as clean and tidy as those you see on the showroom floor at your local dealer. Programming has been simplified, too. The days of requiring a laptop to program an EFI system are gone, replaced with handheld tuners with touch screens. You don’t have to look at fuel maps; just tell the tuner about your camshaft, injectors, intake and even exhaust system and it programs itself.

However, motorsports ECUs still take full advantage of the user who can read fuel maps, spark tables and volumetric efficiency tables. These tuners extract the last bit of horsepower and torque the ECU can give them, and the power they can create is tremendous. Today, with those tuners, we’re seeing cars that spin dynos at well over 900-horsepower on a supercharger and run like they came from the factory that way. That’s the power of modern EFI and those who bury their nose into the laptops instead of the needle and jet box.

So, as an off-road enthusiast who knows more about carburetors than laptops, why should you go with EFI?

“From a reliability standpoint,” says Lawson Mollica, the Marketing and PR Director at AEM Performance Electronics, “you’re not going to get engine protection from a carburetor. Our standalone allows you to tie protection features into oil pressure, oil pressure, coolant temperature, lean protection, engine knock and many others.”

However, the idea of running an ECU probably makes you fear that you’ll easily mess up something or an idea will get lost in translation from carburetors to EFI. Lawson pointed out, “We’ve done carburetor to EFI conversions with even old-school carb guys and found that they get it. They learn it the same way they do anything - by reading and experiencing. We have a manual on our ECUs and it will take you step-by-step through every process. We have tech support if they have questions. Basically, it comes down to understanding the functions and knowing what the basics are.”

So, that’s great from the marketing point of view; how about those who have experienced it? Wes Choate from Sho-Me Speed in Ozark, MO works on Derek West’s Ultra4 car and made the switch from carburetor to EFI on it. “The fuel economy is better and the fuel delivery is better and more consistent,” he said, “especially in the rocks. Throttle response is better, too, along with less contamination from dirt.” For a rock crawler or rock racer, EFI makes sense thanks to the odd angles that will flood out or shut off the fuel bowl when you need it most.

What if you want to swap out an old carbureted engine for a modern LS but don’t want to deal with the stock ECU? “A major change we did to the truck was going from a carbureted engine to a fuel injected engine,” said Nick Isenhouer on his brother, Chris’ 1969 F100 Trophy Truck. “With the Holley EFI system the truck became very responsive and the drivability of the truck became a lot better.” There was another benefit that EFI has over carburetors as well: Data logging from the ECU. “Being able to data log an entire race and go back through that afterwards to make sure the engine is performing at its best ensures that we won’t have any major engine failures when we go to the next race – we are able to make proper adjustments before the race.”

“I started with a Holley HP EFI in the Growler,” said Tony Pellegrino from GenRight. “I swapped in a LS1 and used their engine harness. The HP System was a simpler system that didn’t have a transmission controller. We tapped in to some of the outputs to see oil pressure and I had their display. It ran great and it was easy to tune since you just answered some questions and it gave you a basic tune.”

Now he runs a Holley EFI System on Jordan’s Modified class Jeep that has a transmission controller. However, the Nexus Ultra4 runs a MoTeC M84 motorsports ECU that operates as a full standalone system that controls the engine as well as the Power Distribution Module, C125 Color Display and the Switch Panel. Tony continued, “What’s nice about the MoTeC system, from a driver’s standpoint, is that you can see when things are starting to go wrong. We can pull up things like the amps the radiator fans are pulling, for example, and know if something is going wrong before it causes a major problem.”

What’s great about going EFI today is that there are systems that work with carburetor manifolds. You don’t have to drill out and weld in injector bungs into your aluminum manifold. Companies like FiTec, Holley/MSD, Edelbrock and quite a few others have TBI systems that work on those manifolds for easy swaps. Install the TBI, run a few loomed wires into the cabin, answer questions and the engine begins to tune itself. Hilborn even makes a system with a manifold that looks like their old mechanical injection systems, and Borla makes a system that replicates the downdraft carburetor look of old Weber DCOEs.

If you’re against fuel injection due to complexity, you no longer have anything to worry about. If you don’t like it because of its looks, there are options out there. If you’re going racing on the desert or across the rocks, you need it. Want peak power that a carburetor can give you? TBI has you covered. There isn’t a good excuse for staying with carburetors anymore, except for being period correct. Going EFI has never been easier, and it’s only going to get better.