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.
[15] Another thing to scratch...
[15] 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.
[16] The Avenger wiring harness...
[16] 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.
[17] The wiring was then carefully...
[17] 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.
[18] Finally, the handheld...
[18] 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.
[19] The finished installation...
[19] 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 |
| RPM | HP | TQ | HP | TQ |
| 2,800 | 100.86 | 189.18 | N/A | N/A |
| 2,900 | 106.12 | 192.19 | N/A | N/A |
| 3,000 | 110.46 | 193.38 | 116.79 | 204.47 |
| 3,100 | 113.00 | 191.45 | 122.40 | 207.37 |
| 3,200 | 113.60 | 186.45 | 126.51 | 207.63 |
| 3,300 | 116.52 | 185.45 | 130.50 | 207.70 |
| 3,400 | 115.16 | 177.90 | 134.04 | 207.06 |
| 3,500 | 113.49 | 170.31 | 135.62 | 203.52 |
| 3,600 | 113.59 | 165.72 | 139.30 | 203.22 |
| 3,700 | 113.05 | 160.48 | 141.61 | 201.01 |
| 3,800 | 112.57 | 155.59 | 143.32 | 198.08 |
| 3,900 | 109.18 | 147.03 | 144.02 | 193.95 |
| 4,000 | 111.90 | 146.93 | 144.73 | 190.03 |
| 4,100 | 106.10 | 135.92 | 145.61 | 186.52 |
| 4,200 | 106.25 | 132.87 | 145.18 | 181.55 |
| 4,300 | 106.41 | 129.98 | 145.59 | 177.82 |
| 4,400 | 105.12 | 125.48 | 146.46 | 174.82 |
| 4,500 | 108.78 | 126.96 | 144.81 | 169.02 |
| 4,600 | 106.70 | 121.83 | 144.47 | 164.95 |
| 4,700 | 107.23 | 119.82 | 142.64 | 159.40 |
| 4,800 | 97.92 | 107.14 | 141.15 | 154.45 |
| 4,900 | 91.85 | 98.45 | 137.60 | 147.49 |
| 5,000 | 85.49 | 89.80 | 113.29 | 119.01 |
| MAX: | 116.52 | 193.38 | 146.46 | 207.70 |
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.
[21] Impressed with the fuel...
[21] 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.
[22] The Holley Avenger 4-V...
[22] 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.
[23] Just like the 2-V TBI...
[23] 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.