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tuned port injection

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by newyorkin, Jun 29, 2001.

  1. newyorkin

    newyorkin 1 ton status

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    Hey all.

    Does anyone know what's involved with converting a TBI to Tuned Port? I believe I can get the whole assembly, everything from manifold to computer minus the harness.

    Anyone know what is involved and if the power gain over TBI is worth it? I've never done a FI conversion with used parts. I'm really just wondering, I doubt anything will come of this.
    Here is the TPI assembly I'm looking at, btw: http://k5.8m.com What more is there to life?**
     
  2. HarryH3

    HarryH3 1 ton status Author

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    The harness is expensive, and I don't see the Mass Airflow sensor in the pics. That'll set you back another $300. [​IMG] I think I've read that you can convert from Mass Airflow to a Speed Density system (uses a Manifold Absolute Pressure Sensor) but can't remember who sells it.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://www.angelfire.com/super/ThunderTruck>http://www.angelfire.com/super/ThunderTruck</A>
    It's a great day to be alive...
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Found it! Painless Wiring has a harness that converts from the Mass Airflow to Speed Density system. Check it out at <A target="_blank" HREF=http://www.painlesswiring.com/fuelinj.htm>http://www.painlesswiring.com/fuelinj.htm</A>

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://www.angelfire.com/super/ThunderTruck>http://www.angelfire.com/super/ThunderTruck</A>
    It's a great day to be alive...
     
  4. 88streetblaze

    88streetblaze 1/2 ton status

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    converting to tuned port isn't that hard and the harness will cost anywhere from 300 to 600 dollars but alot of those kits do away with the mass air flow sensor. i am installing an lt-1 in my blazer and haven't had any problems. personally i recomend street & performance they know their stuff and i have had very good dealings with them. and S&P even has what they call an intergrator harness where you can piggy back on your existing harness to intergrate the new system pretty sweet.. like i said it's not hard just take your time and do it right.
     
  5. bigredblazer

    bigredblazer 1/2 ton status

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    I don't know the power gains, but I think it would be easier, and less expensive to redo the TBI. Howell Engine Development will burn a chip, and get you a new throttle body (if needed) it's a lot cheaper than the swap. I know Stephen from ORD ran the Howell system, and will have more info if you want it.
     
  6. 88streetblaze

    88streetblaze 1/2 ton status

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    street & perfomance page is http://www.tunedport.com/
    chech them out. if you do go ahead and do the swap i think you will like it, i don't miss my underpowered 200bhp thottle body injection......
     
  7. 84_Chevy_K10

    84_Chevy_K10 Banned

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    TPI is FAR superior to TBI. In fact, a good carb is better than TBI. It's definitely worth it.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  8. Jason73K5

    Jason73K5 1/2 ton status

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    Even the best carbs still have problems with off-camber driving, this is one of the main reasons that people go TBI.
     
  9. BurbinOR

    BurbinOR 3/4 ton status

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    Guess I'm the poster child for the TPI Lovers society.........did the conversion on my 406SB..........love the thing to death. Just runs so good, so consistent, and when set up properly they make plenty of power. With all the hardware procured, it is a very easy conversion, especially if you already are used to an ECM driven motor. You can see pics of mine on the site below, just click and enjoy [​IMG]!

    I am truly a strong advocate of TPI, for one reason I have a local guru that has converted over 120 cars/trucks of various vintages and models over to TPI...........and everything in his garage, driveway, or that I ever see over his shop is TPI. Has done 108 Jaguar to TPI conversions............


    <font color=blue>'79 ONE TON TPI K5 - See it at---&gt;<A target="_blank" HREF=http://www.blazzinor.alloffroad.com>http://www.blazzinor.alloffroad.com</A>
     
  10. jarheadk5

    jarheadk5 1/2 ton status

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    If I remember correctly, tuned port will make more low-end torque than a throttle body on the same motor due to more efficient airflow, no wetted-walls problems in the intake manifold, and better fuel distribution (with good injectors).

    If at first you don't succeed, failure may be your style...
    [​IMG] Semper Maintenance!
     
  11. laketex

    laketex 3/4 ton status

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    so that means you'd be selling a TBI system CHEAP huh?

    And to the poster that said a good carb is superior to TBI, why? If all you want is something that wont stall on steep inclines, wont a TBI perform the task? What's wrong with them? As long as adjustability isn't like a holley projection, I'm all over finding a cheap used TBI system for my rig.

    Sherman, Tx
    <font color=red>Come Awn yall...Let's go to LUCHENBACH, TEXAS!!!
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  12. newyorkin

    newyorkin 1 ton status

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    You don't want my old TBI, throttle shaft bore is worn out pretty bad... But sure, cheap!

    I don't think I can afford this setup after all, but I'd really like to go for it. Thanks for all the info, all.

    What about other sensors? Coolant/ESC/O2/VSS/Knock, etc? Would the new computer/harness have to integrate with my existing computer, or would there be places for the old sensors on the new harness? MAF to MAP would be better, though, thanks for that info.
    If I did buy the setup, I'd probably be restricted to junkyard parts (on serious budget right now). Would a harness from a wrecked vehicle do the trick?
    Also, would the difference in vehicle wieght be a factor to the computer?

    Ratch
    <A target="_blank" HREF=http://k5.8m.com>http://k5.8m.com</A>
    **K5 - What more is there to life?**
     
  13. mpikas

    mpikas Registered Member

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    TPI vs. TBI is more of a political issue then a ‘which one is better’ issue. Usually those that have a TPI or have done the swap will favor the TPI. Most TBI setups stay fairly stock so many people assume that the TPI has more potential.

    Unless you’re doing something really radical, there is no real advantage in one over the other. Swapping, you might see a little more low end torque with a TPI over a TBI, but you’ll loose higher RPM HP. On a modified motor, TPI usually becomes a big restriction (small runners, 1.25” in diameter) sooner, and it is much more expensive to get parts to compensate. With a TBI you really can run any carb manifold that you want, just use a big block TBI adaptor plate (there are aftermarket ones also). The TBI ECM is more adaptable to changing parts when talking about a speed density setup, but if you use a TPI setup with a MAF (Mass Air Flow sensor), it will be able to compensate for mods by measuring the actual air being ingested by the engine.

    If you’re looking for a multipoint injection setup and have a TBI, Edlebrock sells a conversion kit for just under $1000.

    New Yorkin, to fix your TB, all you need to find is a autoparts store that carries Quadrajet throttle shaft bushings (I believe that they’re the right diameter, if not I’m sure that there is another carb bushing that is close enough). What you’ll need to do is to disassemble the TB, take the casting and drill the throttle shaft hole oversize (I’d use a drill press to make sure that the two sides stay in line) so you could tap in the new bushings, and then reassemble the TB (Most machine shops could do this). If you’re interested in a little more air flow, you could have the machine shop bore the bores oversize and install larger throttle plates (I’ve done exactly that using a jig and a boring bar that I made on my drill press, they start at around 46-48mm, and you can buy 2” and 52mm throttle plates. I did mine to 54mm and custom cut my own plates, ). You can also get a little more airflow by making a small spacer to fit under the injector tower (or just double the gasket)…
     

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