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Thread: Which TBI system is better?

  1. #1
    Electronic Ignition!
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    Which TBI system is better?

    Hi Everyone!
    Need some help and advice...

    I have a 1984 Airstream Motorhome, which I have had a for a few years and am restoring slowly.
    It is based on a Chevy P30 chassis, and has a Jasper built 454, with Banks Power system, and less that 10k miles, and a TH475 trans(HD TH400).
    Bought it in Kansas, and it is a Federal smog version... and I live in CA, so need it to pass smog here.
    It drove great on the way back, and averaged between 6.5and 8.5mpg, which is pretty good for 16,500lb and the frontal area involved!

    Pic from that trip..



    FF to this pic I took last year, of progress so far polishing and making the shell watertight..



    When I began to dig into it, I found that the Carb, that should be a Quadrajet, had been replaced with an Edelbrock, and the smog pump was missing as well as a lot of other smog stuff...
    I thought I had no choice but to find all the missing components, and rebuild/replace them, so that's what I did..

    Period correct Quadrajet, rebuilt with Edelbrock Smog approved aluminum intake, ready to go on.

    With Banks Airfilter housing..


    So, now I find out that I have more options than that... I could put a TBI system on it, and have it inspected and smogged as that.

    I have in my possession 2 systems...
    1/ A 1987 Suburban R2500, 454/TH400 with TBI, complete vehicle(but transmission is toast), that I have owned for 15 years... always passed smog, no problem.
    2/ A 1990 Suburban R2500 454 motor only with TBI system, and harness/computer etc... I think I have everything.. given to me by a friend who didn't need it.

    Which one of the above would be better for the TBI conversion?

    Just one wrinkle in the plan...
    I have a 4L80E under my bench which I would rebuild, and eventually like to add to the Motorhome for its OD and lockup converter...


    Please help?
    Last edited by KeyAir; 11-06-2014 at 12:33 PM.

  2. #2
    Fuel Injected! 1BadAction's Avatar
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    You're going to need a different ECM to run the 80E - I recommend finding a later model harness and 7427 (or 6395) ecm, and using that. They are the fastest updating, best supported TBI ECMs and will give you the most accurate engine/transmission control.

    Otherwise, super nice ride man, nearly the same underpinnings as my Suburban. I love the old Airstreams, I'm waiting for the right time to buy a towable myself.
    2010 Porsche Cayenne GTS - DD
    1991 2500 Suburban - 454ci BBC tow monster
    1979 16' Action Marine/"Johnny Cash" Merc Bridgeport Champ Motor - Metalflake Maniac

  3. #3
    EFI GearHead ! EagleMark's Avatar
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    Basically the 2 systems you have are identical so use the best of both.

    But like1BadAction said neither will run the E trans... you can still use everything and re-pin the newer ...7427 PCM and add some wiring for the trans.

    What's involved with a Banks power system?

    In the end you'll need a cable to hook up to laptop and get some data logs for getting the most out of the tune that comes on the chip inside the ECM/PCM but a stock one will run it.

    Also spend some time seeing what other guys are doing to supply fuel to the TBI unit. It will probably need 2 pumps... one to supply fuel that far and one to keep the pressure suffeicent... and a return line.

    Nice Ride!

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  4. #4
    Electronic Ignition!
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    Thanks for the input Guys.
    So... let me understand this...
    I can use either of the TBI units I have with similar results, but need a different ECU to control the 4L80E?
    Reading the responses... I "could" fit either and "update" the system later?

    My bigger issue is the smog... everyone I am in contact with tells me that the original Quadrajet, barely passes smog here... it just cant control the mixture as well as an injected motor. My 87 suburban ran like a top, blew thru every smog test with its replacement Magnaflow cat and catback system.

    It is my understanding that I will need to retrofit every item from the correct model year to have it inspected and approved by the "Smog Referee". After that, the vehicle will be judged by the smog rules as "a 1987 Suburban R2500" for example.
    My issue is deeper, so I need to go slowly... t
    To retrofit this I need to do not only the TBI/electronics/evaporative system, but also the smog pump/alternator/AC compressor/brackets/belts/pulleys as the setup is different to what is on the Motorhome now. The '84 smog system was all mechanical/temp/vacuum driven.
    The '87 has a odd hybrid belt system, with wide serpentine belt driving the fan/smogpump/alternator, and V belts driving the PS pump and AC compressor.
    If I use the stuff from the '90, it gets worse or better... and that has a single serpentine driving it all, but the waterpump is reverse rotation... and I am not 100% sure I have every single component I need.
    Advice of thoughts?

    Pulling out the 80 gallon tank for a clean and seal is on my list, so I will probably use an in tank pump.. I will have to look at what I have for a return line, and maybe add something.

    From what I understand, Banks Power system for that period 454 was a kit that comprised a tall cast aluminum airfilter housing, a pair of long tube headers, and single free flow exhaust system.
    They claim it adds almost 80hp, and 100ftlb over stock.
    http://bankspower.com/products/show/...20-%207.4L%7C1

    After my drive back from KS, I notced that the Banks Airfilter had been replaced with a "performance" pancake filter... that's what it needs... to ingest hot air from under the doghouse! Agh.

    I was lucky to find the shabby looking Banks unit in a storage compartment, and after some work, and a finding the correct OEM lower, it looked ready.


    If I do this swap... can I expect any performance/economy gains?
    Any advantage in using an Edelbrock TBI intake manifold over the OEM intake?

  5. #5
    Super Moderator Six_Shooter's Avatar
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    I'm not 100% up on Cali smog rules, but I would look into what ECM would be needed to be smogged as the '1987. From what I understand you would likely need to use the '87 ECM to remain in that criteria for smogging.

    This presents a couple avenues. You could use the '87 TBI system, and then use a second PCM or trans controller for the 4L80E later on when you swap that trans in.
    This is a cumbersome way to do it, but may be the best way in light of the specifics of this particular situation, due to Republik of Kalifornia smog rules.

    Moving to the newer PCM, which as a tuner/hobbiest/hot rodder would be my preferred method, due to the simpler overall set-up and more integrated controller, among other benefits, might change the smog standards that you need to meet. You will need to look into this before getting too deep into this project.

    As far as the belt system, that could be set-up with any combination of belts that you want to, as long as the controls are all intact. Personally I prefer serpentine systems, because they are simple and last longer than V-belts systems in my experience. They are less prone to problems as well, such as belt slipping and wear.

    So basically you need to talk to your referee, and see what the rules are explicitly and what changes to the system, namely the controller side of things will due for smog standards.
    The man who says something is impossible, is usually interrupted by the man doing it.

  6. #6
    Fuel Injected! 1BadAction's Avatar
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    Quote Originally Posted by KeyAir View Post
    Thanks for the input Guys.
    So... let me understand this...
    I can use either of the TBI units I have with similar results, but need a different ECU to control the 4L80E?
    Reading the responses... I "could" fit either and "update" the system later?
    .....
    If I do this swap... can I expect any performance/economy gains?
    Any advantage in using an Edelbrock TBI intake manifold over the OEM intake?
    Yes, you can use any 454 TBI setup but the early controllers are engine only. You could use the older setup then upgrade later, but the guys doing the smog checking most likely couldn't visually tell the difference between any of the gm OBDI ECMs, so I wouldn't let that be the only thing stopping me. Then again I don't live there, so they may be smarter than I give em credit for.

    The eddy intake is a ton lighter than the stock intake, there is no adapter donut (one less gasket to leak), it flows a bit better, and it will come up to temp quicker, which is good for running quality and emissions. I would do the smog setup from a 1990, use the 3764, the banks pack, make sure everything mechanical is in good shape, and see if I could find a tune from a motorhome of that era as a baseline.

    Thing about something that big, you can bolt 50hp and 50lb/ft of tq on that engine, and it would be hard to tell. That said, if it's right, with a carefully tuned spark table and the mods you already have, it should run down the highway with more authority for sure. Swap over to that 4L80E and you'll be in heaven.
    2010 Porsche Cayenne GTS - DD
    1991 2500 Suburban - 454ci BBC tow monster
    1979 16' Action Marine/"Johnny Cash" Merc Bridgeport Champ Motor - Metalflake Maniac

  7. #7
    EFI GearHead ! EagleMark's Avatar
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    I've done a lot of Ca conversions and the rules are something like this. First converting yours... there is no TBI conversion with a C.A.R.B. number so no go. Second you can put a complete engine from the year of the motorhome or newer and smog would be from the new motor... in this case you would be doing a motor transplant from a 1990 Chevy truck.

    Having a good freind mechanic get you a sticker is usually the way to go to avoid little nit picking issues of making your 1984 BB a 1990 BB in the end.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  8. #8
    Fuel Injected!
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    Quote Originally Posted by EagleMark View Post
    I've done a lot of Ca conversions and the rules are something like this. First converting yours... there is no TBI conversion with a C.A.R.B. number so no go. Second you can put a complete engine from the year of the motorhome or newer and smog would be from the new motor... in this case you would be doing a motor transplant from a 1990 Chevy truck.

    Having a good freind mechanic get you a sticker is usually the way to go to avoid little nit picking issues of making your 1984 BB a 1990 BB in the end.
    For all they know that engine will be a 1990 454 TBI when it is said and done.

    This is just one more thing I can't stand about tree hugging libtards. Anything EFI is going to run cleaner than anything carb. Requiring an EO number to upgrade to EFI is a a leap of futility if your goal is cleaner air and not making $$$. I am glad I don't have to deal with C.A.R.B. I probably would have written them a letter explaining just how stupid they are if I had to deal with them.

  9. #9
    Electronic Ignition!
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    Ok, thanks for the info.
    I will try to get a read on the engine casting number that is on the Jasper remanufactured engine, as I doubt its a 1984 vintage unit. That might help me.

  10. #10
    Super Moderator Six_Shooter's Avatar
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    I would ask to see if they will plug into the ALDL to verify year of controller. This is what I was getting at earlier about the possibility that the actual ECM/PCM may have an effect on how the vehicle is smogged.

    You need to talk to your smog ref, all we have here (for the most part) is speculation, and from what I've read different smog refs interpret the guidelines differently...
    The man who says something is impossible, is usually interrupted by the man doing it.

  11. #11
    Electronic Ignition!
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    Thanks for the input guys.
    It does seem really dumb to put restrictions on making any vehicle run CLEANER than it did originally, which adding injection, and and a cat will undoubtedly do..
    In the back of my mind, I know it really makes sense to pull out the BBC and put a earlier Cummins 12v diesel in there and have more twist, more mpg, be done with smog. In the early 90's it was a factory option, and I have photos of the installation so I know it works...

  12. #12
    Super Moderator Six_Shooter's Avatar
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    Quote Originally Posted by KeyAir View Post
    <snip> I know it really makes sense to pull out the BBC and put a earlier Cummins 12v diesel in there and have more twist, more mpg, </snip>
    Now you're talkin'...
    The man who says something is impossible, is usually interrupted by the man doing it.

  13. #13
    EFI GearHead ! EagleMark's Avatar
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    Quote Originally Posted by KeyAir View Post
    Ok, thanks for the info.
    I will try to get a read on the engine casting number that is on the Jasper remanufactured engine, as I doubt its a 1984 vintage unit. That might help me.
    They will not be looking for casting numbers... just all the smog stuff on motor working properly.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  14. #14
    Fuel Injected!
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    I would suspect that putting the 87 parts onto the engine and then use the ownership from that truck and the visual proof of the swap in the completed motorhome would get you the approval as a EFI transplant.

    Once that far, changing the PCM and add the transmission later. I expect they just do a visual of the engine smog equipment and a tailpipe sniff.

  15. #15
    Electronic Ignition!
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    Almost finished stripping the TBI parts off the Suburban.
    Di I need the fuel pipes that come up to the TB?

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