Holley Avenger EFI - Fuelish Fantasy
Can upgrading to a bolt-on EFI system really be this easy?
From the May, 2011 issue of Modified Mustangs & Fords
By Mark Houlahan
Photography by Anderson Ford Motorsport
The Holley Avenger EFI system...
The Holley Avenger EFI system comes with everything you need, short of some fuel lines/hoses for creating your return line to the tank. Inside the box, you’ll find the TBI unit, wiring, the ECU, a fuel pump, filters, mounting adapters, gaskets, and an associated small parts kit. Street price for the 2-V Avenger TBI is around $1,799.
Have you noticed, as you peruse the rows of classic cars at a show, that with a quick glance under the hood, you’ll usually find some sort of production or aftermarket EFI system on top of the engine? Yeah, me too. It seems like an epidemic of sorts. People are jumping on the EFI bandwagon for one reason or another. Some of the upgrades can certainly be chalked up to the wow factor, especially if it’s a trick stack injection system or multi-port setup. But we’d hazard a guess that the majority of the converts are simply tired of dealing with fussy carburetors that leak, smell up the garage, don’t run well, return poor fuel economy, and create hard starting after sitting more than a week (which is typical for our vintage cars).
For those of you still running a carburetor I’m sure you’re shaking your head in agreement at that last string of statements. I’ve experienced them myself on several occasions. So what’s stopping you from upgrading to fuel injection? Yes, the cost is a bit steeper than just bolting on a carburetor, but there’s more to an EFI system than just a cast-aluminum fuel distribution assembly. There’s wiring, electronic controls, sensors, a fuel pump, filters, and more hard parts that contribute to that initial cost. So, you’re getting quite a bit of hardware for your entry fee. Maybe you’re hesitant to install fuel injection because you fear the install itself. You’ve seen factory EFI setups and they look confusing with their modern long-runner manifolds and sensors all over the place. Whatever the reason, you need to open your eyes and wrap your mind around the new throttle-body-based EFI systems coming to market today. They’re compact, easy to install, and cost less than many systems found just a few years ago. Best of all, they use a wide-band oxygen sensor and sophisticated programming that allows the EFI system to learn all on its own while you drive; effectively tuning itself as you go down the road.
One of the newest bolt-on EFI systems to come to market is the Holley kit. Yes, Holley, the brand that has brought enthusiasts carburetors for more than 100 years. Holley has actually been involved in EFI product creation for well over a decade, and some of the company’s new hardware is based loosely on its previous throttle body (TBI) and port-injected manifold kits. However, it’s been fitted with a robust ECU controlling the system that makes it plug-and-play simple to get you up and running.
 Here is our test mule....
 Here is our test mule. This ’66 Mustang convertible is used for weekend transportation and doubles as a parade car (truck owners get asked to help move their friends, convertible owners get asked to drive in parades). Anderson Ford Motorsport graciously took time out of its schedule to help us with the installation, as well as dyno testing the Mustang and recording fuel economy measurements both before and after.
Holley has several systems and performance levels in its new EFI lineup. We start with the Avenger line for street and strip use. This is a self-tuning system with a small handheld controller for setup and manual tuning needs. The Avenger is available in two- and four-injector TBI configurations to universally mount on most any Ford intake manifold.
Next, we have the HP systems, which have the ability to be laptop tuned, or tuned via an optional 5.7-inch, full-color touchscreen. The HP is a good choice for big-blocks, high horsepower strokers, and other engines making 400 or more horsepower.
The top dog in Holley’s EFI lineup is its Dominator EFI system, which is designed to be built one part at a time for a custom EFI solution for racing, power adders, electronic trans control, and even data logging. In this article, we’re going to concentrate on the street-friendly Avenger system for the stock 289ci V-8 installation here.
The Avenger 2-V TBI system (PN 550-200) is the starting point in the Avenger lineup, and is good for engines up to 275 hp. That may sound like a limiting factor, but let’s be honest. If you have a stock 289 or 302 and you’re just looking for the benefits of EFI, why pay for more than you’ll need right?
 As we mentioned in the...
 As we mentioned in the opening text, the 289 is stock, save for a Mallory ignition system and some Anderson Ford Motorsport plug wires. The engine still sports its stock cast-iron log manifolds and has been converted to dual exhaust. The owner isn’t looking so much for a huge gain in horsepower, but better driveability, smoother driving (important for those slow-moving parades), and longer drives between visiting the gas station.
 To get under way, the...
 To get under way, the air cleaner is removed and the old 2100 two-barrel gets the heave-ho. Four retaining nuts, the fuel line, and the throttle linkage are all that stand in the way of this carb meeting the recycling bin.
 Due to the stock Ford...
 Due to the stock Ford iron intake manifold’s 2-V pattern, the Holley adapter plate is not a direct bolt-on to this manifold. The instructions state that for some manifolds, an end-user created mounting solution will be necessary. With some careful measuring and using the stock spacer as a template, we were able to drill and countersink new mounting holes.
Due to the stock Ford iron...
Due to the stock Ford iron intake manifold’s 2-V pattern, the Holley adapter plate is not a direct bolt-on to this manifold. The instructions state that for some manifolds, an end-user created mounting solution will be necessary. With some careful measuring and using the stock spacer as a template, we were able to drill and countersink new mounting holes.
 The modified mounting...
 The modified mounting plate is then bolted down to the intake (counter sink screws replaced the original mounting studs) with the supplied gaskets and the TBI mounting studs are installed. The TBI unit is then carefully slid home over the studs as shown.
 You can see here that...
 You can see here that the stock Mustang mechanical throttle linkage works well with the TBI unit, even accepting the stock return spring.
 Since we’ll be using an...
 Since we’ll be using an electric fuel pump for delivery to the TBI, the stock fuel pump and hard line to the carb were removed and a block off plate was installed on the timing cover.
 The Avenger’s ECU can...
 The Avenger’s ECU can be installed under the hood, but be sure to keep it away from direct splash areas (inside the fender for example). We decided to mount it on the left front inner fender. It’s actually fairly hidden once we place the washer bag back on the fender.
The Avenger’s ECU can be installed...
The Avenger’s ECU can be installed under the hood, but be sure to keep it away from direct splash areas (inside the fender for example). We decided to mount it on the left front inner fender. It’s actually fairly hidden once we place the washer bag back on the fender.
 There are two sensors...
 There are two sensors external to the TBI that will require installation. The inlet air temp sensor and the coolant temp sensor. Since the stock manifold doesn’t have additional coolant passage access, we made up this brass tee for the heater hose to install the coolant temp sensor into.
 The air temp sensor is...
 The air temp sensor is nothing more than a bulb-type sensor and a pigtail of wire with a connector. It was nothing to simply drill a small hole in the base of the air cleaner, install a grommet, and pass the pigtail and sensor assembly through it to be in the incoming air stream.
 The EFI system uses a...
 The EFI system uses a manifold absolute pressure (MAP) sensor to determine engine load. The sensor is usually installed on the firewall, but can be mounted directly on the engine. A small bracket was fabricated to mount the MAP sensor right behind the TBI unit to hide it under the air cleaner. The MAP sensor will need a connection to manifold vacuum, as seen here.
 Since we’ll be testing...
 Since we’ll be testing a 4-V Avenger as well, we didn’t get too carried away with making the fuel lines look pretty. We simply grabbed a length of high-pressure-rated EFI hose, connected it to the TBI inlet, and routed it to the Mustang’s feed line coming from the tank.
 For a return line, a...
 For a return line, a length of steel line was routed under the car and back to the rear of the car. EFI-rated rubber hose was connected between this steel line and a brass fitting threaded into the filler neck tube in the trunk. Ensure grommets are used anywhere a line passes through a steel panel.
 While at the rear of...
 While at the rear of the Mustang we also went ahead and finished mounting the fuel system components. A simple pair of aluminum straps made for a quick and easy mounting point for the Avenger’s fuel pump. The kit’s filters were also mounted and new hose was cut to length to connect everything between the tank outlet and the Mustang’s fuel hard line.
This was the perfect system for our subject’s ’66 Mustang convertible. The 289ci V-8 was dolled up with a chrome air cleaner and valve covers, but performance wise it was sporting nothing more than an upgraded distributor and ignition coil. It was stock right down to the iron exhaust manifolds, iron intake manifold, and Autolite 2100 2-V carburetor. The owner was tired of the extended cranking and pedal pumping to get the car going after sitting more than five days. Not to mention it has had four different rebuilt carburetors on the engine in the last few years just trying to get one decent enough to go down the road. Finally, there was the dismal 14.7 mpg he was getting. We felt this was the perfect opportunity to see how well the Avenger system lived up to its sales brochure claims. Check it out in the photos that follow.
 Another thing to scratch...
 Another thing to scratch off the under-car work is the installation of the wide-band oxygen sensor mounting bung. Following the instructions, we drilled a mounting hole and welded the bung to the exhaust pipe.
 The Avenger wiring harness...
 The Avenger wiring harness is mostly a plug and go affair, with just a few loose wires to connect. We started with the simple stuff first; plugging in all of the keyed connectors to their various inputs and outputs.
 The wiring was then carefully...
 The wiring was then carefully routed to the fender and connected to the ECU. The loose wires for ignition, fuel pump, switched power, and so forth were then connected per the instructions.
 Finally, the handheld...
 Finally, the handheld control unit wiring was routed from the glovebox out to the ECU. You don’t have to have the handheld unit plugged in for the Avenger EFI to run, but you will need it for initial setup and any manual tuning.
 The finished installation...
 The finished installation is very low key and doesn’t shout “I’m EFI!” to those who peek under the hood of this Mustang. The only thing visible at first blush is the coolant temp sensor and some of the EFI wiring; and that can be more discreetly routed or covered to blend in better with a little effort.
|Autolite 2-V Carburetor||Avenger 2-V TBI Fuel Injection|
As mentioned before, this ’66 Mustang got just 14.7 mpg using a 60-mile test run on AFM’s Dynojet dyno. After setting up the EFI and answering the basic yes/no questions on the controller, the Mustang started right up on the first try and after a minute settled into a perfect 750-rpm idle. Some cruising at different throttle positions and different gear selections were performed, and then the Mustang was strapped back down to AFM’s dyno for another fuel economy test. This time the Mustang’s 60-mile testdrive netted 20.8 mpg and this was at 12.6 to 13.2 AFR. Furthermore, we had AFM dyno test the Mustang before and after the EFI conversion just to see if the 289 might improve in the horsepower department and we weren’t disappointed here either, with a gain of nearly 30 rwhp. At wide open throttle, the carb registered 10:1 AFR, while the more accurate EFI was making more power while using less fuel with its indicated 12:2-12:6 AFR.
 Impressed with the fuel...
 Impressed with the fuel economy and per-formance improvements of the 2-V TBI Avenger, we decided to take the Mustang’s 289 to the next step and install the 4-V TBI Avenger (PN 550-400, around $1,999 street price) and test it as well. This required a manifold swap. We used a Weiand Street Warrior dual-plane intake (PN 8124) with the correct square bore mounting flange for the TBI unit. The manifold retails for about $150. Notice the extra port in the front water crossover, allowing us to transfer the water temp sensor directly to the intake.
 The Holley Avenger 4-V...
 The Holley Avenger 4-V TBI system bolts directly to the intake without the need for any adapters. The fuel inlet and outlet lines, as well as all of the wiring connections from the 2-V TBI unit plug directly into the 4-V unit. All you have to do is go back to the handheld controller and tell it what Avenger TBI unit you’re using. The 550-400 unit’s rated at 700 cfm and is capable of supporting 200-400 hp.
 Just like the 2-V TBI...
 Just like the 2-V TBI setup, the 4-V unit tucks neatly under the air cleaner for a clean “retro” look. The convertible hit the Dynojet once again for our “drive loop” and as expected, we did see a slight drop in fuel economy (2 mpg), but when you factor in the fuel economy the Autolite carb was getting, it’s still an improvement over the stock induction setup. As for any power gains, we’ll have to report back on that in a future issue, as the dyno operator got a little giddy on the power run and bent a few pushrods. We suspect the power numbers on this near stock engine would be similar to the 2-V TBI though.