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Old 09-26-2011, 01:23 AM
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Injector Question!!! Help!

Hi!
I am building an 87 Camaro with a 700R4 trans, and 2.73 rear gears! The Goal Is Fuel Mileage, & Reasonable Performance! (IE. I want it to be able to get out of it's own way, but I'm not building a hot rod!) I just want something that looks cool, and is economical!
I am building a .020 over 283 with flat top pistons, a retro fit hydraulic 305 roller cam for an automatic transmission equipped car, (Stock Specs On The Cam! Nothing Hot At All, Like I Said! Fuel Mileage Is The Goal!) retro hydraulic roller lifters, the nice 305 heads, with the kidney shaped chambers, (No old school wedge shaped crap!) and GM roller rocker arms, and small tube headers! The compression should be around 9.5, or 9.6 to 1, maybe a little more! (Depending on what calculator I use, piston to deck measurement, and how thick the head gaskets actually are?) But It Should Be Good To Go! (NOT TO LITTLE, NOT TO MUCH! Probably a little higher than a stock 305!) I will use the stock, 87, 305, TPI on this project! Computer and all that! Well Almost All That!
Here is the problem! I'm no expert, but I have done my research and learned that the stock 87 injectors may not be the best choice! I have other injectors to choose from! I have the stock 87 305's! But, I have later ones too, (Like, 1992's I think!) I have a set of LT-1 Gen II Injectors too, but I'm not sure they will fit! I also have a nice set of after market injectors! (I THINK?) (Not sure what they are! Got them off of a mildly hopped up 86 Camaro!) No numbers on them! (Risky!) They are tan in color, Not black! They are not pintle, but they don't appear to be stock multec! When you look at the bottom you see what looks like a ball bearing!
My question is! What injectors should I use? I want the best for fuel mileage! Even if I need to go buy a new set?
I want the best spray pattern I can get, but I don't want to screw up my fuel mileage, driveability, or to say the least, my ECM!
The way I understand it, I can upgrade to a better, or later injector, (Multec) with no problem!
I don't know what to do!
SO!
I hope someone is willing to educate me on this issue, so I can get this correct on the first try!
I would really be thankful!
Your Friend Forever!
Earl
PS..What kind of fuel mileage do you think I can expect?
I built it from the ground up, spared no expense, (God Knows!!) and I don't want to make the wrong choice now!
I will be very thankful for any advice you can give me!
Please share what you have learned with me!

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Old 09-26-2011, 07:27 AM
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Injectors are rated on the amount of fuel they deliver per hour. The bigger the motor and the higher the performance dictates the size of the injectors. Your stated goal of fuel economy puts you into the stock 24 gph that you have. Now you can talk about what is the best manufacturer of the best injector and most will say Bosch and Bosch just may be the producer of your stock injectors. There is one thing you can do to relieve your concern and that is to pull the injectors and send them off for ultrasonic cleaning and testing. I have done this a couple of times with very good luck. I don't have the name of the guy that does this but go on eBay and you will find him. He is in Idaho, Boise, I think.

Now lets talk hardware and software. You are using the early TPI that has the "ninth" injector which serves as a choke for cold starts. Also, the computer is for batch fire using Mass Air Flow sensor for primary control. You are better off going to the next generation computer and control which uses Manifold Absolute Pressure as the primary control, eliminating the MAF. You block off the "ninth" injector because the computer lengthens the injector pulse for up to 90 sec for cold starts. I think the 92 and later computers are the ones you want for this application. Of course, there are some wiring differences so you would have to modify your stock 87 wiring to go this route. Easy enough to take the later model wiring when you get the computer. Since the MAP is the primary controller, vacuum leaks are a big no-no so you need a good vacuum gauge for trouble shooting to make sure you have a good system.

How much fuel mileage are you going to gain? Maybe as much as 2 MPG, but don't get your hopes too high because the stock 87 was not a slouch with a light foot. The 283 by being smaller may do a little better but you are dealing with a system that is tuned for emission standards, not fuel economy.

Trees
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Old 09-26-2011, 10:11 AM
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Correct me if I am wrong Trees, but I thought the stock size injectors for a 305 TPI were 19lb injectors?
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