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Thread: 502-5 TBI Performance?

  1. #1

    Default 502-5 TBI Performance?

    Hi all. Installed a Holley 502-5 TBI. Works fine, but no difference in performance.
    How do you get the Increased Torque & Horsepower up to 25% out of it?

  2. #2
    Join Date
    Dec 2009
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    Quote Originally Posted by bryboob View Post
    How do you get the Increased Torque & Horsepower up to 25% out of it?
    It's "up to 25%", depending on what other engine performance modifications you've done. A larger throttle body alone, doesn't increase performance that much.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  3. #3

    Default

    In other words, just should of kept the original GM TBI and added other engine performance modifications?
    I bought this TBI unit because I thought it would help my slow 5.0L just a little, this was just a quick fix.
    My old TBI was bad, so I thought this would help. I'm saving for a new 5.7L and was hoping to use it on that, but
    now it looks like a bad purchase. (Does not state you need engine modifications to get 25% more Torque & Horsepower.)

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
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    Quote Originally Posted by bryboob View Post
    Does not state you need engine modifications to get 25% more Torque & Horsepower.
    That's not what the advertisement states. It states, "Increased Torque & Horsepower up to 25%".
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  5. #5

    Default TBI 502-5 Wires

    Hi everyone. I've been trying to solve a issue with TBI 502-5 for some time now. It's always running rich and has a hard start have checked many things like fuel pressure, TPS, etc. Went and read the instructions again and was wondering if it's wired right. In the instructions, the wiring diagram has different colors. My trucks wiring harness the wires match your TBI wires, but in the diagram, it says hook the white wire to pink or red. My truck only has white, green, red & blue. So is it right or should it be wired differently?
    Last edited by bryboob; 07-30-2016 at 07:38 PM.

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