2 Big Broncos Rocky Mountain Site
Fuel Injection Conversion
Original entry:
After much thought and research, I have decided to go ahead and swap out the two-barrel carb and install an aftermarket TBI fuel injection system. I figure that going to a four-barrel intake, computer controlled timing, a bigger cam, and better exhaust should free up at least another 50 horsepower from my little engine. I have spent quite some time looking at many FI systems and have pretty much decided on the Holley Commander 950 system.
I have looked over systems from SpeedPro, Electromotive, Haltech, , Accel, Howell Engine Developments, and Holley, as well as stock GM TBI. Speedpro, Electromotive, and Haltech are all sweet systems, but way too expensive for my low-performance application. I looked real hard at the Accel DFI system, but I worry that their TBI system would not hold up well to the abuse of the vehicle bouncing off rocks. It uses standard high pressure injectors with fuel rails hanging off the sides of the throttle body. It looks like a quick solution using on-hand parts. Their MPI systems look great and are very successful, but I am not wild about their TBI system. Howell uses stock GM computers and Holley throttle bodies combined with their own wiring harnesses to make very complete systems that are well-known for their reliability. The reason I chose not to use them, and the same reason I chose to stay away from a stock GM TBI system, is programmability of the stock computer. The GM computer is readily programmable using software and hardware available from many sources, but the system has some limitations I would prefer to stay away from.
The Holley system has many advantages from my point of view. All components except the wiring harness and ECU are readily available at any parts store (except possibly the injectors themselves). All variables in the FI system are tunable. The system will accommodate several ignition systems, relying on GM 7-pin, Ford TFI or crank trigger ignition systems to provide full computer-controlled timing functions. It will adjust readily to my low performance 302 as well as the fire-breathing big-block I may get stupid enough to install later. I prefer the way the throttle bodies are built in the Holley system. They are very close in appearance to the stock GM TBI setup and take up about the same room as a Quadrajet carburetor. A very compact system, important considering the limited dimensions of the 302. Holley had a lot of problems in the past with their analog, 4D and 4DI systems. It sounds like the Commander 950 may have overcome those problems.
Since I am just starting this journey, I will add information as things change and parts are added.
The initial setup looks like it will consist of: Holley Commander 950 700 cfm TBI fuel injection system, Edelbrock Performer intake manifold, junkyard Ford TFI distributor, and a new exhaust system with a high-flow catalytic converter and turbo muffler (yes, single exhaust). Headers are not readily available for my vehicle, so I will stay with the stock exhaust manifolds for now. I would like to investigate shorty headers further. I have one cracked exhaust manifold now, so the decision may be forced on me before much longer. There is a very real possibility that the crack in the exhaust manifold may mess up the O2 sensor reading, so it may need to be fixed before the fuel injection is installed.
For further information on programming stock GM fuel injection systems, see TunerCat and ECMGuy.
Stay tuned for further developments!
12-31-2001
Well, I found a great deal on a welder and an oxy-acetylene kit, so the FI conversion is on hold for now. Hopefully, I'll be able to work on it a bit at a time over the next year and be able to pick up the FI kit next fall. It will happen, it's just a matter of time.
Updated 8-14-2002
I found an HO DFI system off of a 1986 Mustang on Ebay the other day and it was delivered today. It's looking like my EFI system is going to be either a Holley or Accel controller with the HO manifolds and injectors. Both companies offer replacement wiring harnesses with compatible sensors and both can control ignition timing via the TFI distributor. I have had a chance to talk to both companies and now just need to decide which will give the biggest bang for the buck. I'm going to leave the above information in place for now just as background.
I have talked with several people about products like the EEC Tuner and the TwEECer and can't really justify using those products right now. The cost is not significantly different from the Holley system and they are not as flexible (from what I've seen so far.) In addition to cost, these products really aren't geared towards SD systems, they concentrate mainly on MAF. FWIW, they both look like outstanding products, they just don't look right for this application.
I mentioned the exhaust system above. After a few hours with Desktop Dyno, I have come to the conclusion that I will have to install headers. The tough part about it is that the only ones I can find for this vehicle are Hooker Super Comps. About two to three times the cost of other headers. Oh well, they are the best you can buy. My Desktop Dyno sessions also indicate that I need to install a medium range roller cam to get my bottom end power up. Oh, and a 347 stroker looks way cool, too :-)
So, the waiting game starts again as I work up the money to buy the rest of the pieces to finish this project. In the meantime, here are some pictures of my new parts!
Update 7-12-2003
The fuel injection system is up and running! Since the last update I have installed a Megasquirt fuel system controller. This is a very good system for those who want to play with fuel injection. It is very tunable, and extremely modifiable. The Bronc has made one trip to Moab and many local trips with this system and it performs almost flawlessly. Since it is not a high buck system backed by the major manufacturers, it does require some ongoing attention, bit it's a small sacrifice to get a fuel injection system for around $500 (depending on how well you scrounge.)