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670 CFM Holley TBI

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 89GMCSuburban, Nov 28, 2001.

  1. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Who here has tried the bolt-on 670 CFM Holley TBI? Says it will give me 20+ horsepower and torque and decrease my 0-60 by about 2 seconds.

    Red 1989 GMC Suburban SLE V1500 - TBI 350, 700R4 w/ shift kit, Quad-shock front, 31/10.50/15 Pro Comp MT, 4.10 gears, Duals off cat
     
  2. CaptCrunch

    CaptCrunch 1/2 ton status

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    I guess #1 thing here is Don't believe the hype. Don't believe the hp claims. I don't wanna sound like a stick in the mud, but the performance market is almost getting to the point it is false advertising. (2 seconds off your 0-60 time!!! Holley cripes Holley ([​IMG] LOL) that is pretty big jump for just one mod IMO) Until you see it on a dyno, don't believe it! I mean to to bolt on a K&N filter and say you feel a difference is absolutly total "placebo horsepower" (For the record I have seen at most a 5 hp jump on hp w/ a K&N and that was on at pretty high rpm, actually I have seen more of a difference in air cleaner element types then the filter on the dyno). I definetly think it is a good mod for a worked over 350. The real question is does it have bigger injectors with it? I'm not sure what their rating is verses stock, but I assume that the Holley unit is just the TBI and no injectors. I can believe in a bump in hp a bit with some larger injectors, IMO it sounds like all hype and lotsa bucks... just like the TBI spacers and K&N.

    I really think you need to look at the whole picture. Start w/ air flow just to the TBI itself (same in the case of a K&N), you need to look at the air flow up to it. I really think the stock single tube setup is pretty restrictive. Could easily be modded to flow MUCH MORE air by cutting up the plastic piece in the front so air goes straight in instead of the twisted in,up, over and through design. You will want to make sure to try and protect it from water(or go the snorkle route for the hard core offroaders) and use a screen type setup to keep the big stuff out(Also you may want to insert some foam cicles when you go offroading to further aid protection from water and dust... I think you will still flow more air then stock and probably be as well off as the stock setup in terms of dust, then when you go to the more clean elements of the road, you can take them out of you like). Also remember you will need to replace the air filter more often as more dust would get through and for that reason I wouldn't use a K&N filter since they let more dust through the filter. Also a box from the ramairbox.com (dual snorkle setups) would be a great mod and get even more air in.Next I would look at ignition and go w/ a MSD coil, the best Taylor or MSD wires, and plugs gapped at .050 or .060. That will have your air up to the TBI and spark maxed out...then I would look at the exhaust if you haven't yet. After the above is addressed I think then obviously the TBI w/ more flow would be a good mod, but then remember your intake and heads will only be capable to flow so much and of course the injectors and ecm limit your fuel to a point as well. The one wild card of the EFI setup the chip will restrain a lot of power when you get more modified becuase it retsticks the fuel flow more then anything else.

    Basically to sum it up, surprisingly for my age I'm all old school and old tech (probably comes from working for a year in a hot rod shop and my racing experience, I dunno). Keep it simple at first and look at the scientific reasoning behind the stuff. Air and fuel are two big parts to power that are easy to modify. Save your money for the so called quick fix mods and get the fundamentals first and then hit the heart and look at head work, intakes, etc.Then worry about the electrics and look towards the real import guys who know what they are doing w/ AFC and custom engine management setups, or just the nice and simple custom chip. The air box mod would cost from 10 bucks to hack the original up and throw a screen in to approx. 125 or so for the done dual snorkle box. The MSD upgrade would be 50 for the coil... about 20 bucks or so for plugs, and probably 50-80 for the wires (Might as well add a new cap and rotor for 20 bucks too) and most of that will eventually need to be done anyways as maintence. I overall think it would be a better way to spend 200 bucks and then use the extra 100 to 200 more to modify your exhaust w/ headers and true dual setup (cats or no cats... no real matter) the shell out beig bucks for a TBI unit that flows a bit more then stick when it is questionable if you need it. Another mod which is cheap($20) so even if it does next to nothing it doesn't break the bank is one of turbo city's injector spacers. If you have the air coming in, that extra 1/2" of injector hieght at least clears the path a bit more.

    Down the road it would be a great mod w/ larger injectors and a custom chip. I plane to use a similar unit w/ larger injectors, a set of worked Vortecs, intake, Custom burnt chip, and a 260 or 268 roller cam setup. From the carb models in my bud's race shop dyno, I figure it should have a real world 375 hp at 6 grand and about 400 ft-lbs in the 3500 to 4000 rpm range if the chip is burned at the right settings..

    OK...*whew* [​IMG] finally that is my $.02 worth and probably another ten bucks LOL [​IMG]

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     
  3. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Oops, I meant one second. Here's the address http://www.holley.com/HiOctn/ProdLine/Products/FMS/FMSFI/502-6.html The injectors are 65 PPH. It flows 670 CFM and has 2" bores. I agree on the ignition and dual snorkel setup. I have an MSD coil already on it with some Rapidfire plugs. I'm looking at the Crane Fireball ignition, but from dyno tests done on a 350 with several different ignitions, and of all them, the Crane was the only one to GAIN power. All the others LOST power over stock, including the MSD. I'm thinking about headers with duals. That would be perfect, just gotta save some money. Thanks for the advice, you're right. I should just stick with the stock TBI. I know it works.

    Red 1989 GMC Suburban SLE V1500 - TBI 350, 700R4 w/ shift kit, Quad-shock front, 31/10.50/15 Pro Comp MT, 4.10 gears, Duals off cat
     
  4. 89OKIE

    89OKIE Registered Member

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    DON'T WASTE YOUR TIME. I GOT ONE AND IT RAN WORSE. THE PRESSURE REGULATOR IS A PIECE OF S*@$ AND THE INJECTORS ARE SO HIGH UP ON THE BODY THAT THEY SPRAY EVERYWHERE EXCEPT DOWN THE BORE. GET A SPACER AND A K&amp;N FILTER AND YOU'LL BE MUCH HAPPIER. BUT, IF YOU STILL WANT ONE, I HAVE A BRAND NEW ONE STILL IN THE BOX. WILL SELL FOR CHEAP!!!!!!
     
  5. bablazer73

    bablazer73 1/2 ton status

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    I used one as a replacement for a stock tbi. I did notice some performance gain. but stock the tbi had loose throttle shafts.
    this was the cheapest way to fix at the time. I don't know how much is hype, but the truck was ALWAYS lame off idle and there was a vast improvment in off idle responce. I am installing a 4bbl tbi system from holley on my 454 in my blazer.

    your right. I don't understand the jeep thing!
     
  6. Thunder

    Thunder 3/4 ton status

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    Do the exahust work first. Adding more flow/fuel to the intake side will do you no good if you cant get it out the exahust pipe.
    A good flowing exahust will give you the most bang for the buck out of any future performance mods you might want to do.
    Stick with the stock TBI system . It is a far more dependable unit than a Holley TBI. The stock system is also easier to get parts for.
    CC mentioned turbocity.com. I also recomend them. Heres a link to their TBI upgrade page:<a target="_blank" href=http://www.turbocity.com/TBIPowerMain.htm>turbocity.com</a>
    I'v tried many of the parts on that page they do work as claimed.

    <a target="_blank" href=http://coloradok5.com/gallery/Thunders-Blaze>http://coloradok5.com/gallery/Thunders-Blaze</a>
    <font color=blue>NEVADA: Where the pavement ends, and the West begins.</font color=blue>
     
  7. marv_springer

    marv_springer 1/2 ton status

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    bablazer73,

    Which TBI system are you puttin' on the 454? I too am building a 454, and I'm torn between the 750 and the 900cfm version.

    What are your goals and rpm range for the motor?

    Marv
     
  8. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Thanks for the advice, guys. I'll stick with the stock TBI, but what Headers should I get?? I'm looking at the Flowtech Afterburners. Any thoughts?

    Red 1989 GMC Suburban SLE V1500 - TBI 350, 700R4 w/ shift kit, Quad-shock front, 31/10.50/15 Pro Comp MT, 4.10 gears, Duals off cat
     
  9. CaptCrunch

    CaptCrunch 1/2 ton status

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    Marv? Where did you find a 750 cfm TBI and the 900 cfm tbi for that matter? Thnaks


    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     
  10. HarryH3

    HarryH3 1 ton status Author

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    Capt, check out this: <a target="_blank" href=http://www.holley.com/HiOctn/ProdLine/Products/C950/C950TB/C950TB.html>http://www.holley.com/HiOctn/ProdLine/Products/C950/C950TB/C950TB.html</a> [​IMG]

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

    CaptCrunch 1/2 ton status

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    I'm not sure who did the testing you are referring tooor what rpm range (obvious ignitions are for higher rpm, not lower) but I doubt the msd lost power if it was for the right application. I really can't see 90% of the world's racers being wrong. I have heard great review of the Crane fireball ignitions. Crane has had some problems wityh their earlier model ignitions but looks like they nailed it this time. Personally the stock ignition does fine for up to 4500 rpm, so unless you go over it I wouldn't worry about a ignition box. Just open up the gap on them plugs if you haven't cause that is how you will see the power gain. I have heard awsome reviews of the Afterburners, but some not so rave reviews about trying to get them. I guess almost everywhere has them on backorder. My buddy has a set on backorder from Jeg's... he also tried Jeg's, Northern and numerous others. Good luck

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     
  12. CaptCrunch

    CaptCrunch 1/2 ton status

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    Thanks HarryH3... I tell ya if I was any closer to the page it would of bit me in the behind LOL. [​IMG]

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     
  13. marv_springer

    marv_springer 1/2 ton status

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    Er.... Sorry it was a 700 cfm version...

    P/N HLY-950-22S in my Summit Catalog. $1329.95

    Marv
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    I think this is what he was referring to www.dorianyeager.com/index2.html
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  15. bablazer73

    bablazer73 1/2 ton status

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    I am using the 900 cfm 4bbl. I am expecting 600+ ftlbs of tq and that or more in hp. stock bore with 9-1/2 comp. comp cams roller cam good to 5,000 rpm. roller rockers and many other speedy parts!! I am an x drag racer, so speed is my pleasure. I am also thinking of N.O.S. if thats not enough

    your right. I don't understand the jeep thing!
     
  16. marv_springer

    marv_springer 1/2 ton status

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    Thanks for the info...

    Your sights are a little higher than mine! I think the 700 would serve me better. I too am looking for a 5000 rpm rev limit, but I'd be happy w/ 400-425 HP.

    Marv
     

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