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Going to injection, stock or holley?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by outlaw612, Aug 6, 2001.

  1. outlaw612

    outlaw612 1/2 ton status

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    Im wanting to go to fuel injection, so I have a couple of questions. Which is better, Holleys projection or stock TBI. By better I mean ease of install, what are the pros and cons of each? What all do I need to get if I do the TBI? Would it be easier to swap the whole motor? Thanks for your help.
     
  2. 84_Chevy_K10

    84_Chevy_K10 Banned

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    This has been brought up this week already.

    Nobody liked it but I told them neither. If I was going to go through the trouble I'd get a port injection setup. TBI does have advantages, but port injection of some kind simply cannot be beat.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  3. 1990K5

    1990K5 1/2 ton status

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    stock tbi simply can't be beat
     
  4. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    i am sure it can. otherwise holly would not sell it. may ne be beat in the way we care for, but it can still be beat.

    i would go with TPI myself. a stock setup would do fine and it is simple. they make a lot of harness and tinkering toys for them too. lots out there for both.

    if it was me, and soon will be doing this i would find a camaro motor and put it in. then tweak it here and there.
    Grant

    1974 Chevy Blazer Cheyanne. but it is on 33's now, with saggy old springs. i am in Yuma Arizona if ya got any parts for me.
     
  5. 1990K5

    1990K5 1/2 ton status

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    holley tbi units are the biggest pieces of s##t ever made, i know from much experience with them, and, tpi is a waste of time on a rockcrawler.
     
  6. blazer72

    blazer72 1/2 ton status

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    TPI is instant power. Unlike TBI or a carb, TPI will rap if you just hit the pedel. Carbs and in a lesser way TBI depend on flow to get the fuel in to the port. A true TPI injects the fuel right in to the chamber. so there does not/is not always a vacum under WOT. One thing that is a thing of the past is flooding due to angel with TBI or TPI. Even the best of carbs have an angel were they flood.

    With that said a stock GM TPI is good up to about 350 CI after that point, if the motor sees high RPMs, more CFM in needed. more CFM means more money on runners and air doors. A stock GM TBI is good for about 650 CFM. But unlike the TPI the TBI can be used with almost any intake manfold that a carb be used on. TBIs are cheaper to work on the last ime I had to buy injectors for my TPI it was about 80.00 each, 8 times. Injetors need to be matched. I spent 100.00 to have 8 cleaned. TBI injectors are about 80 to 100 each too. But there are only 2 of them most times.

    I had both a holloy 650 and a 900 di system, the 900 was gift from holley after I tryed for over a year to make 650 one work. Holley had lots of problems with the first system manly the design team walked out shortly after the first systems hit the steet. I have seen some work and work well the one on Steve's yellow truck works better than most. And I think that Keith is installing one now or shortly will be. Ask both of them for input they use them and like them. I run an Electromotive ECM and first TPI manfold with 31# injectors on the 406 in my 72, and the stock TBI on the 406 thats in my 93 with stock injectors with 145K miles on them, the only change the 93 need to make the 406 run right inplace of the stock 350 mas to up the fuel flow be uping the fuel PSI from 13# to 14.5# The fuel rate was found use the info on MSDs site on injector sizeing.
     
  7. CaptCrunch

    CaptCrunch 1/2 ton status

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    I agree w/ 72... TPI kicks @ss compared to TBI, but TBI is better then noth'n. I would personally try and go the stock swap... It can be done cheaper, but overall the Holley would be an easier swap to do... just plug and go, but you may end up having hassles if you have a 700R4 tranny because it uses some of the sensors to lockup, but you could get a vac conversion kit for it.

    TPI is gret down low, under 4500 rpm so it makes a sweet truck motor and will net better power and milage. Look at BlazinOR's truck... one sweet motor... might be worth a look into before you settle for TBI.



    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://www.geocities.com/milnerlives_2000/blazer.htm>http://www.geocities.com/milnerlives_2000/blazer.htm</a>
     
  8. 85GMCJimmy

    85GMCJimmy Registered Member

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    What do you guess think about Edlebrock's setup to convert a carburated truck to a TPI? They run for about $2000, would i have that much more performance gain? I have a 350 in my blazer that has a quadrajet on it, it's aobut 3 years old
     
  9. 1990K5

    1990K5 1/2 ton status

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    i don't doubt you know exactly what your talking about, the tpi is hands down more responsive than tbi, but just from a great performing and reliable, simple offroad setup i still say the STOCK TBI CANT BE BEAT!
     
  10. realsquash

    realsquash 1/2 ton status

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    TPI will just rap? What science is that based on? Neither system actually injects the fuel into the chamber, most of the time it hits the back fo the intake valve and when the intake valve opens and the pressure drops, in goes the fuel. This is the same with TBI, but TBI just injects into the runners and eventually makes it down to the ports.

    As far as vacuum at WOT, well I don't know what your statement means.

    Squash
    <a target="_blank" href=http://www.trailrunners4x4.org/users/realsquash>http://www.trailrunners4x4.org/users/realsquash</a>
     
  11. blazer72

    blazer72 1/2 ton status

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    WOT = Wide Open Throtle And yes a a good TPI system fires the injector every engine rotation so there is fuel there as sone as the valve starts to open and the injector is fired when the valve is open most not all shoot the fuel right past the open valve, or spray it all over the openning. This means that the TPI system is not as dependent on vacume to get a rich charge in to the cylinder. Makeing the TPI system resond to changes in the throtle much faster than TBI or a carb.
     
  12. pcorssmit

    pcorssmit 1/2 ton status

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    What you are referring to is called sequential port injection. I believe the TPIs, at least the earlier ones and maybe all of them, are batch fire systems, meaning that all the injectors fire at the same time. Usually at a closed valve.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  13. Thunder

    Thunder 3/4 ton status

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    For ease of install I would go with a GM style TBI. Personally I like TBI. Just because it is simple. I like things simple. They can be used on any size engine up to a 454 with good performance and gas mileage. And they work great off road.
    I think Aftermarket TBI systems are the best way to go as most used TBIs are getting pretty old and componets are getting wore out. If you are going to spend time and money on the installation, buy new. The technology it tried and true is dependable and works well.
    It is a lot cheaper than a MPI or TPI system and requires far less modifications.
    I don't like holley stuff it always requires a lot of work and tinkering to make it work right. Everebody I know who has had Holley pro jection works on it a lot and have a lot of injector problems.
    The GM system is basicly a plug and play and forget about it. They are built for the 350 engine so there isn't a bunch of modifications to do.
    I recomend TBI systems from either of these companies.
    http://www.howell-efi.com/complete_kits/tbi_index.html
    Both make good systems based on the GM TBI.
    I dont want to argue with anyone about the merits of MPI/TPI VS TBI. These are just my opinoins. I have GM vehicles with both systems. They both work well. I just like TBI because it has less parts and operates on lower pressures and has been so dependable.
    Thats my 2 cents
     
  14. blazer72

    blazer72 1/2 ton status

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    Cant say for the stock GM TPI unit Mine is sequential. I'd have to check but I thought the later GM ones are too. The accel TPI one is also as are most of the aftermarket ones. TBI is much easyer to set up and use. Lots cheaper too. I also have had good luck with parts from turbo city.
     
  15. pcorssmit

    pcorssmit 1/2 ton status

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    You may be right (about the later GM ones), I seem to remember them making the change, but I can't remember if it was in the TPI years or the LT1s.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     

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