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vortec head/egr question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by downtime2nite, Jun 20, 2002.

  1. downtime2nite

    downtime2nite Registered Member

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    it's finally all coming together, new short block(5.7)vortec heads, headers, comp cams hyd. roller cam & 1.6 roller rockers, holley tbi,now the last two things- intake manifold and computer chip- going with the fast chip, question is, should I worry about the egr valve or have the chip disable it? have some concerns about plumbing the egr to the new manifold. any help greatly app. keep up the x-cellent posts.
     
  2. 84_Chevy_K10

    84_Chevy_K10 Banned

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    If you don't have to smog it, ditch EGR.
     
  3. Sandhills Blazer

    Sandhills Blazer Registered Member

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    If I ditch the EGR will I get the Check Engine light on all the time? I'm building a Vortec 350 for my Blazer now. Am also adding roller rockers in addtion to the roller cam. Plan now is to use the Edelbrock Performer manifold with the adaptor from Holly and the Holly 670 TBI. I hate seeing that light on as I drive past people on the road. Makes me want to stop them and ask them if they know why that light is on.
     
  4. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    You can't run it the traditional way on Vortecs. The exhaust crossover passage in the middle of the heads are cast shut from GM. I think Vortec vehicles have a tube comming of the exhaust manifold to suck fumes from.
     
  5. Nrose07

    Nrose07 1/2 ton status

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    Vortec is advisable, and I'll tell you why. 1st the reason the Vortec system dosen't have the passages in the heads is it is a multi-port F.I.system. Its injectors are positioned right above the intake valves, this means the intake is a dry manifold. No fuel flowing through it, no need to heat it to keep the fuel atomized. They only reason they have a EGR is for emmisions and lower combustion chamber temps.
    When you convert the Vortec heads to a wet intake system (TBI or Carb) you will run into drivability issues with the fuel staying atomized and not pooling. I belive this is a larger issue for the TBI then the carbs, reason being you have 2 big injectors in a large 2 barrel. A carb has 4 small annular discharges in 4 higher velocity barrels, and you only have 2 open most of the time.
    So a EGR system will heat the intake and keep the fuel atomized. But you can only run EGR if you have the GM performance intake. BUT you say I can't run that because the throttle bores are to small for my Holley 670cfm. Well Bore it out to 2.00" it can be done safely, I did.
    If you really want to run the Performer, well don't! Get the Performer RPM, it has a crossover passage under he intake pleneum. Run coolant through this and it will help drivability alot! BUT this is still not going to give you the power or drivability of the GM performance TBI/Vortec intake. I know, I've done both. Only the GM intake is designed for the flow properties of a TBI. If you use the Performer series with the adapter it will create a lean condition in your front 4 cylinders, deadly! The adapter sits the TBI to the rear of the motor, not centered.
    Plumbing the EGR, Edelbrock makes a kit to run EGR on your headers. Can find info on GM Performance web site. Stock Manifolds, well you can but is not easy. You have to go from the #1 cyl. air injection port, up and back to your intake with two different style fittings. Easiest is to go a drivers manifold of a Vortec pickup, but the exhaust dumps in a different location so exhaust system will need to be modified. I like headers since they help the flow of the Vortec heads.
    Computer PROM. Yes you should get a custom tailored PROM. Yes your light will come on if you don't run EGR. DO NOT RUN A GENERIC CHIP! Run your stock one if nothing else, but you will need one burned for your specific combo.
    Well hope I didn't overwhelm you, have fun, and if anyone has other opinions or questions just shoot!
    Matt
     
  6. Nrose07

    Nrose07 1/2 ton status

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    And I forgot about valve lift issues. If you are getting close to .500" then you want to upgrade springs and machine the valve guide bosses down. Sounds like alot but really dosen't cost that much.
     
  7. Sandhills Blazer

    Sandhills Blazer Registered Member

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    Thanks for all the information. What are you running in your Blazer? You said that you had bored out the GM performance manifold to 2" with no problems. How far down in the manifold did you bore it out to 2"? Since I have not looked at one of the manifolds, I don't know how deep it should be bored out. How much difference will the 670 make over the stock TBI from GM?
     
  8. JIM88K5

    JIM88K5 1/2 ton status

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    Thanks for the tips !!! I've posted a question about using an aftermarket intake with a TBI adapter and not got first hand experiance. A vortec 383 is my plan. Looks like I'll use the GM intake...
    Jim
     
  9. downtime2nite

    downtime2nite Registered Member

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    woo-hoo lots of info, so, if I use the G.M. performance tbi intake for the vortecs, it is plumbed to hook up to the stock A.I.R. system- the a.i.r. sytem "feeds" the e.g.r. valve with exhaust gas.(I'm using edelbrock t.e.s. headers with a.i.r. fittings?) which is basically stock except they are headers. also I ordered the vortec heads from scoggin-dickey with the h.p z-28 springs and machined slots for a high lift cam (only $290 apiece) can"t wait, visions of horsepower are dancing in my head! thanks again
     
  10. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I hate to say this, but this is why I'll never build a motor with Vortec heads.

    They're a great value on some applications but the aftermarket competes real well with them. World Products S/R torquers are a better bang for your buck IMO, and if you're going to build a motor more than 350 CID, they're probably a better idea. On top of that, you can use a regular exhaust gas crossover and a regular intake of your choice.

    There are many applications where Vortecs are a great idea--but one like this, with all these coolant/EGR issues on a fuel injected motor is not one of them in my opinion.

    They're a great head, but when the aftermarket can use regular intake, gas crossover, EGR, rocker arms, etc., it's just cheaper to go that route.

    Just my 2 cents worth anyway.
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    No, AIR doesn't feed the EGR.

    EGR *is* exhaust gas, AIR is *clean* air injected after the combustion process into the exhaust manifolds. (on some other makes of motors, right near the exhaust valve in the head) Thats why there is an AIR pump, and an EGR valve.
     
  12. Nrose07

    Nrose07 1/2 ton status

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    The TBI/Vortec intake gets bored into the pleneum, just a few inches. I'm running 670 holley on my intake. And as it was explained above the A.I.R dosen't feed the EGR. If you plumb EGR into your headers you need the factory pipe that goes from the intake to the exhaust manifold. So hope it helps!
     
  13. Sandhills Blazer

    Sandhills Blazer Registered Member

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    Thanks for the info. How much difference did the 670 make over the stock TBI from GM? Is it worth the cost to go to the 670 in the Blazer? I don't plan to have 500+ horsepower with the 350ci. I'll be happy with 350+ horsepower.
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    not to be petty, but 350 is pretty optimistic unless that motor is really wild. Going with similar setup you are (vortecs, roller cam, roller rockers, TPI though) and am only looking at about 275hp (not rear wheel) but about 425ftlbs.

    http://yeagerd.home.mindspring.com/TPImotor.html

    (bottom one : )
     
  15. Nrose07

    Nrose07 1/2 ton status

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    Stock L98 engine with aluminum heads -250 hp
    L98 with Vortec heads and TPI Intake - 300 hp
    With ZZ4 cam and 1.6 rockers on the intakes - 335hp
    With Hot Cam - 360hp
    TPI VORTEC INFO
    Looks like 350hp easy with the TPI. I was going to do his untill I saw the asking price, still going to just not this year.
     
  16. Diesel Dan

    Diesel Dan 1/2 ton status

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    When adding the vortec heads don't forget to drill them for the coolant by pass, if you don't you have to plumb one externally. Like a big block from the water pump to the coolant crossover on the intake. Just use a head gasket for a template and drill.

    I have a set of L31 heads in the garage that just might end up on the '91. Already has Edelbrock headers, just ordered another 3" flowmaster exhaust. Then the 670CFM TBI unit, thinking about installing the factory L31 roller cam also.

    Don't have AIR fittings on the headers so I'll fire up the wire welder and install a 3/8"NPT fitting and hard pipe a 1/2" stainless hydrallic tubing with 37 degree JIC fittings.
     
  17. dyeager535

    dyeager535 1 ton status Premium Member

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    I notice they conveniently left out the RPM's that those numbers came at.

    Bet if you did more digging, you'd see that motor didn't peak HP until 4500RPM or so, and had worse low end torque than a smaller cammed motor. IE, thats a car motor, not a heavy, big tire, wheeling rig motor. Some of the stuff isn't going to hurt, but the cam for sure hurt low end, and getting 50HP with heads AND a new intake aren't really impressive, given the 40HP claims by most places on a Vortec head alone swap.

    Don't get me wrong, I'm building a Vortec headed TPI motor with that intake, but the low end will flat out kill that motor, I'd bet on it. (and I got a desktop dyno graph to prove it! Whats SDPC have?? lol)
     

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