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school me on vortec heads

Discussion in 'The Garage' started by K5Greek, Mar 3, 2007.

  1. K5Greek

    K5Greek 1/2 ton status

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    ive tried searching but only found post with people saying that they want to put on vortec heads..

    what i know is that itll give me a little power boost, ill need a new intake manifold, and i think have to run on premium gas(not sure).

    what i want to know is will this help out in gas mileage at all? what else am i missing? also are these the same heads off 96-up 350s?
     
  2. 1977k5

    1977k5 3/4 ton status Vendor

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    They are on 96 and up 350's and they will help mileage.

    You need centerbolt valve covers too.
     
  3. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Better mileage is doubtful.
    Yes they are on 96 and later 350's
    If you need to pass smog inspection then you'll need to figure out how to make your EGR valve work as there are no passages in the heads for EGR.
     
  4. Thunder

    Thunder 3/4 ton status

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    Not better gas mileage milage. Your TBI heads are a little better in that department.
    You can run on 89 octaine with Vortecs no problem as long as you dont go beyond the stock 9.2 to 1 CR
    As said above need to plumb EGR.
    Should also get better than the stock cam. Wont see much power gains with the stock cam.
    Should also get a chip programed for vortec heads and cam.
     
  5. K5Greek

    K5Greek 1/2 ton status

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    well nj doesnt smog so i can just plug it up. as far as the mileage is concerned i wont really lose any either will i?

    does anyone have any part numbers or anything for the intake and valve covers i would need?
     
  6. Thunder

    Thunder 3/4 ton status

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    Are you doing this to the 91 Blazer you have in your sig? If so you already have centerbolt valve covers.
    If you just plug the EGR you will take a further hit on your gas milage.
    ECM is programed to look for EGR operation if it does not see it it makes changes to timing and fuel. Hiway MPG will do down. Also your CEL will come on. You can get a chip programed to delete the EGR function.
    You can get the manifold from any GM parts for around $380.00 They are the only ones authorized to sell them. You can usually get them on Ebay too.
     
  7. jms

    jms 1/2 ton status Author

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    Last edited: Oct 6, 2007
  8. Dudge

    Dudge 1/2 ton status

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  9. sled_dog

    sled_dog 1 ton status

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    Looks like some really good info there. Only thing I have to question is the 480HP potential out of stock "out of the box" Vortec heads. Maybe some of the aftermarket Vortecs like the GMPP Large Port or the E-Tecs, but not stock GM Vortec heads, I just don't believe 480HP. I've seen numerous write ups in magazines of 400HP Vortec headed(stock) engines but 80 more HP is just pushing it in my mind.
     
  10. K5Greek

    K5Greek 1/2 ton status

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    so if i plug up the egr and get my chip reprogrammed to run without it, would that affect my mileage? or will i get about the same with that compared to what my truck is getting stock
     
  11. K5Greek

    K5Greek 1/2 ton status

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  12. Dudge

    Dudge 1/2 ton status

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    If I'm thinking of the same build the heads werent stock. They were machined for bigger springs, and he ran a pretty beefy cam. I also believe he did a little cleaning up on the ports and bowls.....
     
  13. K5dreamer

    K5dreamer 1/2 ton status

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    Vortec heads are pretty damn awesome out of the box for a 350, but for a 305 there is quite a bit of work that needs to be done to get benifits.

    First off, the castings you want are the ones with the casting number that ends in 062. These heads are found in the silverado, tahoe, suburban, and GMC equivilants that have the 8th digit in the VIN as the letter "R".

    the castings to avoid have the casting number ending in 908. these heads were used in the larger commercial trucks like box trucks and have a pressed in cast iron valve seat on the exhaust port that limits exhaust flow.

    the stats on the heads are that they have the 1.94in intake, 1.5in exhaust valve setup, with a 62cc combustion chamber. if you have a 350, this will probly raise your compression a small ammount, however if you are running a 305, chances are youre running a 58cc chamber, and the vortecs are going to lower your compression quite a bit, maybe as low as 8.5:1.

    as was mentioned, youll need to do something about the EGR setup, either by making it run (which i reccomend, better for performance and gas mileage contrary to common belief) or eliminating it in the computer. and a vortec specific intake.

    as for the 480hp sbc, you would have to look at cam selection, intake setup, exhaust, and many other variables, but i whole heartedly believe its possible on stock vortec heads, they certainly flow enough air, and have very efficient combustion chambers.
     
  14. sled_dog

    sled_dog 1 ton status

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    Ok, Vortec heads have a 64cc combustion chamber. Most 350s(especially TBI) have 72cc chambers. How is the 6cc difference between the 305 and Vortecs going to greatly drop their compression, but the 8cc jump down in size won't really affect the 350?

    I do believe you aren't thinking this out very well.

    And the EGR, if you have the system, I say run it. It doesn't really hurt performance(unless you consider exhaust port flow on older heads with the crossover ports), and it can help to improve fuel mileage. However it will NOT gain performance. How is filling the cylinders with inert gas that is doing nothing for power production going to INCREASE power?

    The biggest fuel mileage gain seen with Vortec heads is the Vortec fuel system. The reason a 96 gets better mileage on average than a 95 is the more advanced fuel system. Its not the combustion chambers or the EGR system(they both had one after all).

    I'm sorry I do not believe in stock trim a pair of Vortec heads will help an engine put out 480HP. **** the variables, I understand what all goes into an engine, and I just don't believe it. Now, massage the heads just a bit, and sure I will believe it. And when I refer to "stock trim" I mean ports, chambers, valve seats, and valves. I understand the need to modify the spring seats, valve guides and such for high lift.

    And since I don't know that I've ever talked to you, please don't take me the wrong way. I am an asshole through and through, so things come off really mean when I don't intend them to be.
     
  15. Thunder

    Thunder 3/4 ton status

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    I really dont know. It depends on the chip program and what your tune is.
    But IMHO vortecs on a mild build 350 will never give as good of MPG as Stock TBI heads.
    I wil venture a guess tho doing a vortec swap. You will see about 2 MPG decrease in gas MPG.
    This is assuming you have a well tuned stock TBI 350.
    What kind of mileage are you getting now.
     
  16. K5dreamer

    K5dreamer 1/2 ton status

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    vortecs are advertized as a 64cc head, however the pair that i have on the shelf for my IROC were measured out at close to 62cc's, thats what i go off of. As for the difference in compression with the 350, its true that the older 350s run the larger chambers, and that the vortecs will raise the compression more, id run the math but it depends on piston dish, yadda yadda and theres really no one answer on the ending compression. when i did my research i was looking at newer 350s in the camaro line, which run the smaller heads, so thanks for pointing that out for me as i missed it.

    as for the 305 vortec combo, hotrod did that in a camaro, and to get decent compression, they had to machine the deck surface at an angle, and then correct the intake mating surface as well, to make the heads fit and get a compression ratio of i believe 9.6:1.

    as for performance with the egr, semantics, poor word choice on my part, i was talking about how well the engine worked, and with the egr, it runs cooler, produces fewer emissions, and there isnt a loss of performance, which means your using less fuel and running more efficiently. although by running cooler you prevent detonation and depending on weather or not you have a knock sensor, it might actually provide better performance ;)

    I also agree that the fuel delivery system makes a big difference in fuel mileage, but i dont agree that you can so easily brush aside the effect of a more advanced combustion chamber design. the reason the vortec heads make so much more power than older heads is that they more efficiently burn the given air fuel mixture, more power for a given ammount of fuel means that you can use less fuel for the same power levels, which means in similar driving conditions, the engine that more efficiently burns its fuel, will get better mileage, simple thermodynamics. any time you make an engine produce more power without adding more air or fuel, it will produce better fuel consumption rates, as an example i give you the early ZO6 corvettes, that put out 405 hp, and get 30+ mpg on the highway. accomplished through combustion efficiency.

    also, its not nessesary to modify the vortec heads for higher lift, a set of beehive springs from comp cams fits over the stock valve guides and allows up to .525in lift. i dont have the part numbers off the top of my head, but i can find em if nessesary. as for the engine not producing 480 hp on the stock heads, like i said, it depends on the variables, to take it to the extreme, are you saying a turbocharged sbc with vortecs wont make that power? i dont recall if it was said it was NA, but im just sayin, theres alot i didnt know, i just said it was believeable. never said you could bolt those heads on an otherwise stock engine and put out magic power levels.

    as for the disclaimer, no worries mate, i raise a beer to ya, always nice to meet a fellow ass, i work at a shop, trust me im used to it ;) i dont claim to always be right, but i never speak unless ive done some sort of diggin into somethin, like i said, ive got a set of the heads on a shelf to go on my IROC, so before i put them on my car i researched the hell out of em, although admittadly its late, and im shootin off stuff from the top of my head rather than my notebooks, so if i get somethin crossed up, id rather be called out on it than lead someone astray. kinda one of the nice things about the forums ;)
     
  17. K5Greek

    K5Greek 1/2 ton status

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    with 3.73s and 33's i was getting about 14 ish in town, never really do highway
     
  18. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Before going and throwing a large lift cam you better make sure you have the clearance between the retainer and the top of the seals/guides. Most any SBC with lift in excess of .480" needs to have the guides machined down to clear the retainers.
     
  19. K5dreamer

    K5dreamer 1/2 ton status

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    again, with the beehive springs, the vortecs will run a .525 in lift. no machine work nessesary
     
  20. NoReGrEtS

    NoReGrEtS 1/2 ton status

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    I too will be getting me some vortecs soon, but how big can you go with press in studs?
     

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