What Are Your Upgrades To The TBI 454?
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What Are Your Upgrades To The TBI 454?

  1. #1
    Join Date
    May 2008

    Default What Are Your Upgrades To The TBI 454?

    I saw another thread on here sorta about it but it went nowhere.

    I have a 1991 Crewcab Dually with the TBI454 / 4L80E combo. This thing doesn't scream up hills or anything but empty with the shell on and the AC off at 55MPH I can see 17MPG on cruise control and we have done it several times because we assumed something was wrong at first. We only have smallish boats by today's standards so all we do with it is carry a camper, tow a 20' Schiada RT, an 18' flatbottom, and a small enclosed dirt bike trailer. We may add another 24' TT Spectra XS but not soon. Not to be controversial but I like the TBI454 for several reasons.

    Relative Simplicity
    Cheap to Maintain / Replace
    Enough, if not overwhelming, power for my needs
    Efficient, surprisingly so, in my experience

    It's kinda cheaply engineered
    Power is not too far above minimum
    All the systems are just above minimum IMO

    So I'm wondering others have done to make this engine more efficient. I see Gale Banks says you can increase HP by over half and TQ by a third using basically a different air horn and his exhaust and perhaps a chip. Banks Power | 82-95 GM - 7.4L>>PowerPack® System

    All I have done is Thorley ceramic coated headers. I am not interested at this point in swapping in the 8.1L/4L80e combo from a Sub or 3/4 ton pickup, or in the Vortec 454 swap.

    I had a relative who had one of the blown (by Gary at Eclipse Engineering) Chevy 454TBI crewcabs duallies in the 90s and it was nice but the power wasn't alot more and it had heating problems and would pass most things but a gas station.

    We have done alot to our dually over the years including building a four link rear suspension, gusseting and bracing the frame for 5K payloads, airbags on all four corners with compressors, braided lines etc. When something goes we try to go back in with the best stuff. We really like this older body style. It will be the last truck we own and just about the time my kids inherit it well, it oughta be about perfect.

    Am just assuming that with all the motorhomes out there that these went into there must be some basic upgrades in efficiency that don't mean billet heads and CAN-AM injection.


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  3. #2
    Senior Member roughneck427's Avatar
    Join Date
    Apr 2014
    Fresno CA


    I will say ive burned a few chips for these for several trucks. There is a 60 sec delay on power enrichment which means its at 14.7:1 for 60sec under WOT before it starts adding extra fuel to get 12.5:1 is where id set it. Thats why you see alot of those trucks with cracked exhaust manifolds. Another thing they have no timing in it lucky to see 13 degrees in the heavy load areas. I can tell you will pick up a bunch with just tweaking those few things. Tunercat is free for 30 days and if you care to look i can send you a .bin file if you care to tune your own truck.

    And being its a 4L80 the ECM controls the shift pints you can bump the line pressure to extend the longevity of the transmission
    Last edited by roughneck427; 06-05-2014 at 09:40 PM.

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