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throttle body injection help

Discussion in 'The Garage' started by S. Burnham, Nov 14, 2005.

  1. S. Burnham

    S. Burnham Registered Member

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    I am building a motor for my 88 GMC k5 Jimmy. I am building a 383 with 6.0 inch rods and 383 hypertec flat tops, stock tbi heads( I plan on upgrading later just can't afford any right now), 270 adv. dur. cam with .495 int. lift/dur @ .050 .218 degrees- .502 ext.lift/dur @ .050 .224- lobe speration is going to be 108. this is a hydrolic roller cam. I want to keep my TBI but i need a chip to run with this setup. I would like to have the egr removed from the computer because it is no longer on the engine. From my understanding the egr will make the engine run lean at normal crusing speed. I will be using headers as well so do the O2 sensors need be removed to be an open loop system like a marine engine, or would it perform better with O2 sensors? I had one guy tell me that the tbi want run at all with that lobe seperation because of vacuum, and he could not burn a chip for it. Another guy said that he can't burn a chip for my application through the mail. I know I can't be the only person that has built an engine with this set up. If it had to be ran like a marine engine that does not use a map sensor or O2 sensors that would be fine. I want the throttle body for crawling where a carb will fail. Can any one help me on this matter. Thanks for any info on this, it is hard to find anyone who knows anything about fuel ingection. I feel like their is some one on this site that has tackled this before me.
     
  2. 1-ton

    1-ton 1/2 ton status Premium Member

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    What those guys told you is correct. It is almost impossible to get any 2-barrell factory type TBI and ECM to run with the engine you are building. Even the most high performance Holley "Pro Jection" 2-barrell TBI system is only good to a maximum of 275 HP. There are other options. The easiest would be to use a carburetor. Another one would be to buy an exspensive aftermarket fuel injection setup like the Holley 950 commander, which will come with it's own Electronic Control Module. These units are good all the way up to 800 HP.
     
  3. K5Steve

    K5Steve 1/2 ton status

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    I would switch to tpi.That's what I'll do if I keep my k5.
     
  4. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    You're pushing your luck a bit with that one. have a look over on Thirdgen. The only way you're going to come close is by burning your own chips. I've bought all the gear and to be honest, it's not that tricky messing about with it. Having said that, getting it right is a bit tougher. But with eeproms you can just keep reburning chip after chip for free until things start looking good. Keep the O2 sensor for sure, if you can afford it and are doing your own tuning, get a wide band O2 as it makes tuning easier and more accurate.
    look at all the links and posts on thirdgens DIY efi boards, also take a look at Craig Moates site for info and chip burning parts. Tunercat is a good source too.
    But I still think you're going to struggle with those specks.
     
  5. sweetk30

    sweetk30 professional hooker Premium Member

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  6. S. Burnham

    S. Burnham Registered Member

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    he was smart @@s and i don't think i will be using him.
     
  7. BigRed89

    BigRed89 1/2 ton status

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    The short block sounds like a nice set-up, will give some good low end torque. I'm just curious as to why you chose that particular cam? If you're going to be crawling, you really don't need that much lift, etc. Your plans in wanting to change out the stock heads are good. What intake are you going to run? As stated previously, keep the O2 sensors, and locate them so they are not too far down the exhaust system. Good luck with the build!
     
  8. S. Burnham

    S. Burnham Registered Member

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    I have stupid answer for the question. This had started out as a replace the crank and sell the k5, until I found that it had 2 bent rods, 4 broken piston rings, 8 cam lobes missing, 8 mushroomed lifters, and all the rod bearing had spun. The funny thing is I drove the k5 to the spot that I pulled the motor. any way I found the stroker kit on e-bay cheaper than I could build it back stock. The cost difference was the $200 balancing fee. Then I decided to go roller with motor. After bidding and finding what I wanted on e-bay I had every thing but the cam. I intended on going with a used stock roller cam, but the crazy people on e-bay were paying $150 for a used cam. So I have all my parts but a cam and I find a good deal on this one. I plan on replacing the cam later. I am just trying to get it back on the road so I can get back and forth to work. The tbi from I understand won't compensate itself for the extra cube's, so I am going to have to a chip for that anyway. If I come across a good cam that is smaller I will put it in instead of the 270, But right now I am stuck with this one. Prime example of not knowing enough about what you are doing before you buy parts. Let my stupidity be an example to everyone else. I haven't built a motor in 12 years, so I am having to learn all over again the hard way.
     

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