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Discussion Starter #1
Hey Shane I was wondering what all is involved with converting an old skool mechanical fuel injection system to efi. Do you need a computer and various sensors etc to make this work? I'm sure its beyond my capabilites but i was just wondering.... BTW your motor looks awesome:) :cool: :)

 

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You do need a computer and some but not all the sensors of a modern car. I used an Accel computer(the older gen 6 version). With Alpha N tuning you don't need much in the way of sensors. The main brain as far as sensors are concerned is the throttle position sensor(TPS). Not only does it control the fuel map but also does the timing if the dist. is computer controlled. I used the small HEI from Camero/Firebirds 88-92 or full size V8 truck 88-95(?). A map sensor is not needed. You could get away without an air temp sensor but a water temp. sensor will make warm-ups easier. You need an Idle Air controller(IAC) to let the computer control the idle(warm-ups, a/c, and auto. trans. engagement). A knock sensor can be used to help protect the engine should the timing map be wrong. It shouldn't be used as part of the timing control though because when it sences detonation it pulls the timing back to a safe margin which in turn is not an optimum setting. Right now I'm in the middle of doing an Enderle(similar to the Hilborn seen above) for the 421. I'm trying to set it up to tune in a conventional manner using a map sensor to fine tune the fuel and timing maps. A vaccum line has to connect to each port below the butterfly which in turn is connected to a common manifold. This will supply a vacuum sorce for the map sensor. I also need another set of eight vacuum lines, to go to a manifold, to supply vaccum for a pcv. Then I need eight more lines connected to a manifold which is connected to the IAC. This supplies makeup air to control the idle. I wanted these lines to be hidden so I've run all the lines and manifolds under the intake. from the underside of the intake I have three lines coming out the rear of the intake which will go to respected places. Very busy looking under the intake with 27 vacuum lines and three manifolds. All for the sake of making the intake look simple and uncluttered above. Sorry for the long post. You're not asleep yet are you?
 

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Discussion Starter #3
Shane, thanks for the info....not to worry about the length of the post it was very informative...not a chance I was asleep....lol....have you ever ran the old mechanical injection as is or have you always modified it to efi? :)
 

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Always modified it to efi. It can be run on the street but it's a very difficult tune and not really the best way. Mechanical fuel injection, of these type of systems, have fuel coming out of the injector jets 100% of the time. bypass system meters some of the fuel for the engine and returns the rest back to the tank. The problem is in setting the two or three bypass set ups so that the fuel is metered correctly sothat not too much or too little is getting into the cylinders. Efi times the delivery in pulses of fuel at the time it needs it. Batch fired fueled systems send fuel in twice(once when the valve is still closed) while sequential systems send in the fuel once in the four stroke sequence. Of the two types of systems the sequential is the better but it does come with a price. That being the price.
 
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