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I've heard of FI to carb conversions(especially in 3rd gen F-bodies, those boys love their carbs) but never of a carb to FI. Is that because its impossible? I know injectors would have to be added, computer hooked up, etc. But is it possible and would it be worth it?
yes it's possible, it's been done to my mini cooper :) i also recall on another forum someone mentioned in passing their friend was doing it on a 1950's yank tank of some description, so i assume it's not uncommon?
Its quite common. Just depends on what sort of system you run.
[QUOTE=KingNothing;761969]I've heard of FI to carb conversions(especially in 3rd gen F-bodies, those boys love their carbs) but never of a carb to FI. Is that because its impossible? I know injectors would have to be added, computer hooked up, etc. But is it possible and would it be worth it?[/QUOTE]
Mainly because the TPI fuel injection system on the 3rd gens is tuned to be optimal at about 3500 rpm due to the runner length... which isn't good for increasing power. And many 3rd gen owners are old fashioned. I love fuel injection though.
As for a carb to injection conversion, they're not a problem. Taking the 3rd gen as an example, if you had a carb, there are aftermarket products like the superram and miniram (one's made by Holley, iirc) that, along with a stand alone ecu, would replace whatever induction system you had. Any carbed engine could be made into fuel injection- difficulty depends mainly on the availability of parts and/or what has to be custom made.
I changed my Mustang from carb to injection. Some people fear Fuel Injection because of the many computers and sensors that can break, but the efficiency and cold-start were enough to make me change. It is more expensive than running a carb setup, but who wants to adjust their car for certain weather conditions(a carb problem)? Also, I enjoy being able to hook up a computer to my car and being able to view all types of engine data.
I have done a portion of this job, i.e. replaced the Bosch D-Jet ECU in my 1972 Volvo 1800E with a modern, programmable EFI system from Simple Digital Systems (SDS).
In the case of my 1800E, I retained most of the Bosch "hard parts", e.g. fuel injectors, intake manifold, fuel pump and fuel pressure regulator. I replaced the Bosch D-Jet ECU, throttle position sensor, air intake temperature sensor and added a wide-band O2 sensor in the exhaust. A narrow-band O2 sensor may be all you need in some cases.
For a carb to EFI replacement you will have more parts to replace but the programming of the system isn't any different for having started from a carb instead of starting from an obsolete EFI system lacking an O2 sensor.
There are vendors who provide throttle bodies which have the same form factor as the carb which you are replacing. For instance, SU side draft throttle bodies, DCOE side draft and down draft throttle bodies in a variety of form factors to attach to a stock carb manifold. There are manifolds for Ford and Chevy V8's which will give you 8 individual downdraft barrels so each cylinder gets its own throttle plate.
Unless you already have an electric fuel pump you need to install a new fuel pump, fuel pressure regulator and a return line which sends extra gasoline back to the fuel tank. Sensors generally consist of a throttle position sensor, manifold air pressure sensor, coolant temperature and intake air temperature sensor. You can generally purchase these as part of a matched system by selecting the correct parts from the EFI vendor's parts list. You will also need an appropriate fuel rail and hoses to bring the fuel to the injectors.
Different vendors provide different means of programming the system. SDS provides a small programming panel which connects via serial interface to the ECU and can be disconnected once you have programmed the system. Some other systems require a laptop computer. The programming interface with these systems is generally more sophisticated. The added sophistication may make programming easier if your way of thinking and the program are in synch with each other.
The installation and programming manual for SDS is pretty good. You can obtain a copy as a PDF document from their web site. I can't tell you anything about the others.
I did the Bosch D-Jet to SDS conversion because the Bosch system has limited adjustment range and does not have closed loop feedback. It was not capable of providing a correct A/F mixture under a wide range of operating conditions after by Volvo engine had been rebuilt with selected performance enhancements.
It's very common, in fact it's one of the hottest trends around in vintage Mustangs.