Vortec Cylinder Heads: The Definitive Guide

Discussion in 'Engine Topic' started by MikeM79, Jul 4, 2006.

  1. MikeM79

    MikeM79 Moderator Lifetime Gold Member

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    Mar 5, 1999
    East Quogue, NY
    Guys,

    Dave "Dirt" Reynolds has suggested that we devote some space on the message board to Vortec heads.

    Cylinder heads are arguably the most important link in the "power chain", so it is certainly worth its own dedicated area for discussion.
     
  2. Dirt Reynolds

    Dirt Reynolds Veteran Member Lifetime Gold Member

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    Mike - thanks for the sticky. :cool:

    I'm sure anyone interested in Vortec heads will find this thread to be quite useful and informative for their own Vortec engine build and questions concerning using the same. The idea is for anyone with Vortec experience and/or info to post here in this thread so as to pool our Vortec knowledge. Anything Vortec-related is welcome.

    So -- without any further ado, I'll start things off. :cool:


    What exactly are "Vortec heads"?

    Beginning in 1996 to '00, L-31 Vortec heads were installed from the factory on GM truck and van 350 engines. These newly designed for 1996, state of the art heads are made from cast iron and replaced the former swirl-port TBI heads that had been previously used on the GM truck 350. Instantly the HP rating increased 55HP to 255 HP primarily from the power of these cylinder heads.

    What makes Vortec heads any different from other GM steel heads?

    Pretty much everything. Beginning with the intake port, which is 170cc with a cast-in 'ski jump' on the port roof which is there to increase port flow velocity, port flow was designed to be high in the .300"-.500" valve lift area to make power with relatively low-lift truck camshafts. The bowl area is wide around the guide - much wider than the old 'camel-hump' heads from back in the day - and the intake valve seat has a 3-angle grind from the factory. The intake valve is also back-cut as is the exhaust. The exhaust port, considered to be the "weak" part of the otherwise steller-flowing Vortec head, actually does not flow that bad but because the intake port is so good, responds better to port work than does the intake and there is a strong feeling in some camps that these heads make best power with a split-duration camshaft because of this aspect. The exhaust valve seat also comes from the factory with a 3-angle grind and back-cut valve (except as noted below). The combustion chamber design was a radical departure from anything GM cast in iron prior to the introduction of these heads, and is of a 'double-quench' design. Highly efficient, best power is made with 32° total timing, although these heads can make power with timing reduced to 29° when used with short-duration camshafts.

    How many versions are there of 'Vortec' heads?

    Realizing that today, several manufacturers have tooled-up their own reponses to GMPP's highly successful debut of the L-31 Vortec for the budget small block crowd, thus far we have several versions to choose from in the performance aftermarket:

    GM L-31 Vortec
    GMPP 'small port' Vortec Bow Tie
    GMPP 'large port' Vortec Bow Tie
    GMPP 'Fast Burn'
    Edelbrock E-Tec 170
    Edelbrock E-Tec 200
    Dart Vortec replacement head
    RHS Vortec
    EQ Cylinder Heads Vortec

    L-31 Vortecs -- there are two castings with two versions of one of these castings (#906). The two castings are the #062 and #906. The #906 is the same as the 062 with the exception as noted below. Using the 906 heads myself, I can safely say do not worry about any percieved weakness in HP potential in comparison to the 062. They both make the same amount of power. The 062 is the head you will get when buying the Vortecs from the dealership/GMPP.
    • Vortec heads were designed based on the 1996 Caprice 9C1/Impala SS LT1 cast-iron head castings. The only difference is the water jacket revision so these heads could be used on conventionally-cooled small blocks. The 1996 LT1 cast-iron head was the highest-flowing LT1 head used by GM. These heads outflowed the Corvette/f-body aluminum LT1 heads reportedly by 20 cfm on the intake side. The cast-iron head was in development 6 months longer than the aluminum head and during that time GM engineers tweaked the ports for the additional flow.
    • Two Vortec castings were used from 1996-99 on GM CK trucks ('00 in vans) and SUV's utilizing the Vortec 5700 350 engine. The #906 and #062. The #906 casting head was available in two versions. One has an Inconel exhaust seat with a single angle grind, and the other has the conventional 3-angle grind on the exhausts as per the #062. The #906 with Inconel seat does not intrude into the exhaust port. It was used primarily on the HD and 1-ton truck applications where sustained towing of heavy loads & weight up inclines could cause eventual damage to a standard induction-hardened exhaust seat from excessive heat.
    • The only difference between the #062 and #906 Vortec head is in the exhaust seat of the HD/1-ton truck #906 version, as described above. The #062 has a 3-angle grind on a standard induction-hardened seat, as does the non-HD #906 head. The 062 does flow slightly better on the exhaust side at low lifts but the advantage over a 906 is very slight. They both utilize back-cut exhaust valves. They both have 3-angle grind seats on the intakes with back-cut intake valves. Both heads make the same power in stock form.
    • Vortec heads were used exclusively in trucks and SUV's. No passenger cars were equipped with these heads.
    • Stock out-of-the-box Vortec heads have approx. 480HP potential naturally-aspirated. Fully race-ported flowing 275 cfm @ 28" water with 2.055/1.60 valves, potential is approx. 580 HP. There are reports of some shops getting close to 300 cfm out of these heads in fully-ported form.
    • Retainer to guide clearance is the primary Achille's Heel of the Vortec. For valve lifts above .460" they need to be checked for R-G clearance. This varies from head to head. Some find they can get .480" and slightly more valve lift fine. Others will find .460" about the limit. Always check R-G with any performance cam above .460".
    Great, I'm interested in Vortec heads, but am concerned about retainer to guide clearance. What can be done about this, and, are there any places I can buy Vortecs already modified for use with high-lift camshafts?

    Good question, easy answer.

    Scoggin-Dickey sells Vortec heads already correctly modified for use with high-lift performance camshafts. They also sell a complete kit which has the modified Vortecs, intake manifold (Edelbrock Vortec), rocker arms, etc to basically bolted on your existing short block.

    Sallee Chevrolet has an interesting solution to this problem (from their website):

    The Sallee Chevrolet solution is to use Crane Cam’s 10309-1 drop-in valve spring and retainer kit which is good for .550” lift with no machining. The installed height for this Crane Cams kit is taller and the lower part of the retainer is shorter. The “AVERAGE” clearance between the retainer and seal is .575” for this kit. We have found that some of the Vortec heads, coming from the factory, do not have the valve seals driven on all the way. You need to check that they are before installing this kit. If they need to be driven on all the way, we have found that a 3/8” drive - 1/2” socket fits the valve seal just about perfect.As with all modifications to performance engines though, you should always measure to assure that there is proper clearance and fit.

    Comp Cams sells a tool that will cut down the size of the Vortec valve guide and is around $50 or so.

    Another method is the infamous Vortec retainer "ghetto grind". If the camshaft being used only requires a stock 1.25" diameter single-wound valvespring, it is possible to only need to grind off approximately 3/32" off the bottoms of the stock Vortec retainers with a grinder or on a grinding wheel to achieve enough R-G clearance to run up to approximately .530" -.540" safely. I must caution here that R-G clearance must ALWAYS be checked to verify that there is in fact enough clearance - also include allowing for coil bind. One other thing - you must remove the dampner in this modification. Don't worry -- the stock Vortec valveguide being much larger in diameter than other SB heads will act as sort of a dampner and I never noticed any RPM issues related to lack of running one when I did this mod. Although myself and others who have done it this way have had no problems, I must caution this basically for those on a strict budget and cutting down the guides either with the Comp tool or at a machine shop is the best way to go. However, I'm of the opinion that since it works well within the noted constraints, then you're really only out your time to grind down the retainers. The choice is yours.

    More to follow. :cool:
     
    Last edited: Aug 14, 2009
  3. Dirt Reynolds

    Dirt Reynolds Veteran Member Lifetime Gold Member

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    Spark Plugs For Vortec Heads:

    5613611 R44LTS, set of 8
    5614210 MR43LTS, set of 8
    25164641 #3, Rapid Fire style, set of 8
    P526S Accel U-Groove “SHORTY” Double Platinum Header Plugs approximately 3/16" shorter then R44LTS plugs, set of 8
    RS12YC Champion
    Autolite 104 or 26
    ACCEL 516
    Bosch HR10B or HR10BX, HR9DC
     
    Last edited: Jul 4, 2006
  4. hardline_42

    hardline_42 Veteran Member Lifetime Gold Member

    Dirt, awesome Vortec info as usual from you. I believe the new GM Vortec Heads are casting number '060' but they retain the '062' characteristics like you mentioned. What are those EQ heads you made reference to? Also, with Sallee Chevrolet's solution to the R-G clearance issue, wouldn't installing taller springs require longer valves or machining down the spring seat?
     
  5. Dirt Reynolds

    Dirt Reynolds Veteran Member Lifetime Gold Member

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    Hardline -- yer close but what you are quoting with the '060' is the part #, not the casting # thusly:

    PN 12558060 = Casting number 12558062

    EQ Heads -

    HERE is their website on their Vortec head replacement. I first saw their ad in Chevy High Performance, and the product pictures show a really nice casting. Beyond that, I don't know anyone who is using them. Maybe someone here is and can tell us what they think of these heads?
     
  6. Dirt Reynolds

    Dirt Reynolds Veteran Member Lifetime Gold Member

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    The below posts are from Gary Penn, formerly of GM Performance Parts. These posts were taken from the Team Camaro and Team Chevelle bulletin boards over a period of a few years. Gary no longer works for GMPP having taken a position at Hardcore Motorsports. However -- the below posts are pure gold for the Vortec enthusiast, and are a highly interesting read from the man who was at the GMPP helm during the Vortec 'revolution'. Enjoy. :cool:

    The Gary Penn Vortec discussions:

    Part 1: Gary Talks about the Vortec combustion chamber design.

    "Here is the short version of the importance of combustion chamber design. First some assumptions, air fuel ratio is right, meaning enough present oxegen to support total combustion of the fuel. Second, forget about the "crevice", the area above the top ring between piston and cylinder wall where the fuel will not burn efficiently. Third, assume flat top piston, best design, promotes most rapid flame travel. Now compare a theoretical combustion chamber with piston at tdc and no air movement. This of coarse would never happen, but bare with me. To burn the fuel would require maybe 60 degrees of timing lead, because you have only the close proximity of the fuel atoms to spread the burn from the plug accross the area of the chamber. This would mean your engine would "fight" against building combustion pressure as piston approached tdc. Very inefficient. "old fashioned" combustion chambers are more desireable than our theoretical case because they induce turbulence. The turbulence speeds the spread of the burn, but in a random and uncontrollable fashion. Requireing maybe 34-38 degrees ignition timing lead. Better, but still not great. This is all heads built prior to the early 90's. And, most aftermarket heads, which are "tweaked" copies of "old fashioned" production heads. Now consider the Vortec head with its predictable and repeatable swirll patterns. Faster burn rate than our previous examples, requireing even less timing lead, about 30-32 degrees, therefore engine has to fight the mounting pressure less than the previous examples. This means more power available to put to the ground, or up in smoke I guess. The theoretical ideal engine would have such a fast burn rate that total combustion would happen at the moment of ignition. Then you could run 0 or 1 degree timing lead. Don't hold your breath waiting for this to be reality, the laws of physics aren't cooperating with us on that one. Make sense to ya?
    Regarding port design, "total area under the curve" is most important. Most buy heads based on peak claimed flow at some valve lift (ie. 250 cfm at .600" lift.) But more important than that is flow at all levels and particularly low lift flow. If you chart your flow at all valve lifts from open to close it looks like a bell graph (the line will be shaped like a bell). The fatter the bell the better. A narrow pointy bell is no good. Also, you need efficient flow management, that is laminar flow without turbulence in the ports. Turbulence creates "voids" or low pressure pockets that mean your port will not pass as much air as the same port witout turbulence would. Laminar flow takes the air through the port intact, essentially fills the port with quality air without "voids". Another thing to consider is velocity and momentum. Air and fuel have mass, so they can be accelerated and will have momentum. The Vortec head uses a venturi built into the port shape to accelerate the air/fuel after it makes the turn toward the valve. This creates low pressure behind it, drawing more air/fuel. And it gives the air fuel high velocity and momentum so that it has a lot of energy when it hits the back side of the open valve, because at this point it has to be redirected and loses energy as it's redirected.
    So, bottom line is best high velocity laminar flow at all valve lifts with a controlled high swirll chamber, combined with a flat top piston. Currently, no aftermarket head can begin to compare with the Vortec, even the Fast Burn lags a little behind in the quality of these characteristics."
     
  7. Dirt Reynolds

    Dirt Reynolds Veteran Member Lifetime Gold Member

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    The Gary Penn Discussions -

    Part 2: Gary talks Vortecs in general.


    "Enough is enough. Here is what I know about vortec heads. Intake flow comparable to LT4 heads. Exhaust flow comparable to LT4 up to .300 lift then lags just slightly behind (not enough to notice.) Max valve lift is .460 to .480 (range is due to production line machining/casting variance, check for clearance on anything over .460". Stock vortecs, modified only for valve lift will make 410-420HP on a high compression shortblock 355 (typical circle track engine.) Vortecs require a Vortec style 8 bolt intake, they should not be modified for older 12 bolt style intakes, not enough section thickness for proper bolt retention at the location of the center bolts. Also, most intakes can't be ported enough to match the raised intake ports on the vortecs. Durability of the vortecs is not a concern, the reference in the catalog is for the 8000 rpm,13 to 1 circle track guys. These heads have been installed on millions of trucks and thousands of hot rods. We sold 8700 of these in 1999 and already exceeded that number this year. We have never warranteed one sold for high performance applications. If you buy vortecs, keep your reciept, if it breaks (and it would be the first one) I'll replace it. Just contact your dealer, they know how to get to me.
    Oh, and by the way, there are no true fast burn aftermarket heads...only from GM, we are at least 10 years ahead of the aftermarket in combustion chamber design.
    Regarding porting, a little clean-up on the vortecs is OK, but if you dramatically open up the ports you lose the venturi effect in the intakes that makes them flow and perform as well as they do.
    The vortec head was designed by the same guys that did the LT1 and LT4, one of which was a former GM winston cup head engineer for over 10 years, he's back at GM Racing doing race heads again.There is no head for a 23 degree smallblock which is more technologically advanced in terms of flow management and combustion management than the vortec. Have a great day and by the way we invented the small block, who do you think knows it better than us?"
     
  8. Dirt Reynolds

    Dirt Reynolds Veteran Member Lifetime Gold Member

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    Gary's "Cheap Street" Vortec Camaro build-up. Note: a few years ago, Car Craft magazine ran a class for two years called "Cheap Street". The idea was to run a small block with a limit of 360ci, only unported heads from a limited list of 'budget heads', and restrictions on a nitrous plate system. It was CC's way of trying to get the average car guy racing within a limited budget. Too bad not enough guys ran that class to keep it going, but what became apparent by season 2 was that the quickest and fastest guys seemed to be running Vortec heads. Here is Gary's Camaro build, which he was going to run in this class. This is a compilation of several posts on his car.

    The Gary Penn Discussions -

    Part 3: The Vortec Camaro "Cheap Street" Project:

    "With the juice 649 HP @ 5900 RPM, 611 ft lbs @ 5300.

    Without the juice 479 HP @ 6100, 446 ft lbs @ 5100.

    Used 4 bolt production block, bored .060.Hard block filled.
    Used production forged crank, rod journals turned down to 2.000 (from 2.100)
    Light rods, 5.7 inch.
    Diamond flat top pistons, custom machined valve reliefs (small as possible.)
    Second hand Hamburger oil pan, full length kick-out, stripper screen.
    6.75 inch damper.
    High tension top ring, low(none) tension second ring, standard oil ring.
    Solid flat tappet cam, .485 lift, custom nitrous grind from the comp catalog of lobe profiles. Comp solid lifters with hard face and EDM oil hole in base.
    Previously owned Vortec heads, 2.05/1.60.Angle milled one degree, 50cc chamber, 12.5 to 1 CR. Serti valve job. No porting, light spring retainers. Comp springs w/120lbs on the seat.
    Crane 1.5 gold roller rockers. 7/16 studs.
    GM single plane Vortec intake.
    750 mighty Demon.
    1.5 inch open carb spacer.(tried several, this worked best.)
    MSD fixed timing dist. 32 degrees N/A, 26 on the juice.
    1 7/8 x 33 headers, 3.5 inch collector 12 inches long.
    Nitrous Works plate w/.063 jet.
    VP C14 fuel.
    10W30 oil, 7 qts (minus what was leaking out of a bad weld in the pan, gonna have to fix that.)
    ARP and GM bolts/studs throughout.

    Fuel is VP C12. Car is street legal (more or less)and plated, but you wouldn't want to drive it too much more than a head turning roll through town. Converter is very drivable considering its specs. Heads were rolled one degree to get the chamber to 50cc from 64. Peak power is at 5900, but still makes good power at over 7000. We measured it on a dyno to 7200. I shift it at 6500 (1-2)and 7000 (2-3) and cross the line at 7200-7400. Duration is about 270 at.050. Hope to dip into the tens this weekend with some better air and less wheel spin, it'll either work or it won't.

    Koni's and Lamb's seem to be prefered by hard core sportsman racers in stock and superstock. I have Koni SPA's on my car.

    Nothing too trick here, just a well thought out combo with parts that compliment each other. Thanks for playing the guessing game and congratulations to the winner....if in fact there is ever agreement on who that is.

    [Comments he made from a later post:]

    Unported Vortec's. The car is 90 percent finished. I was installing gauges today.

    The engine build was in Super Chevy about two months ago, don't remember the cover date. Title was Cheap Street something...But the good stuff isn't in the story...can't give it all away.

    Brian Thomson (engine builder) was at the house a couple weeks ago checking out the car, his comments were "car looks great...I never thought the engine would make it off the dyno." Inspiring words from your engine builder, huh? In fairness to Brian, we pushed well beyond the limits of sanity on the head milling, that's what he was refering to.

    We made 480HP w/o NOS and 650 w/ NOS, all with a .485 lift cam and flat top pistons.

    The car will make its first passes in April, looks good on paper, can't wait to see it in action.

    [Track results from a later post:]

    My Camaro made its first passes last weekend. 3200 lbs, Vortec heads with no porting, 11.16 @ 119.76 with a little wheel spin. Going back saturday to try to do better, made adjustments to the car to get rid of the tire spin....I hope. It was an absolute hoot to drive, love the trans brake and the 5200 RPM launch. 1.62 60 foot and 100 mph at the 1/8 mile. Too much fun. I know it's not a Chevelle, but thought you guys could appreciate it anyway.

    358 CI.480 HP at 5900.7400 redline. 485 lift solid flat tappet cam. Flat top Diamond pistons (12.5 to 1). Aluminum GRP rods. Junk yard crank and block. Vortec heads with 2.02/1.60's, no porting. 750 Mighty Demon on GM Vortec single plane. MSD Ign, 4.56 12 bolt. Hughes THM 350 w/ 8" converter. 10x26 Mickey Slicks. Launch at 5200 and hang on.

    Gary"
     
    Last edited: Jul 4, 2006
  9. Dirt Reynolds

    Dirt Reynolds Veteran Member Lifetime Gold Member

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    The Gary Penn Discussions -

    Part 4: Gary talks about the HP potential and airflow of Vortecs.

    "Two years ago we undertook an exhaustive (no pun intended) study of the Vortec head in numerous modified states with different valve sizes, throat cuts, valve jobs, port mods, guide mods, etc. We used up about 10 heads, numerous valves, and about $50,000 worth of labor. The study generated 100+ pages of flow and swirl data,which I have at my desk.
    Here is the short version. Out of the box, .480 valve lift, 350-400 HP dependant on the CR, cam, ring seal, oil control, blah, blah, blah.

    More than .480 lift, cut the guides down to clear the retainers.

    Straight mill up to .060 safely, .080 with low CR of 10 to 1 or less. 0.100 is living on borrowed time.Always use flat top or dished pistons to enhance flame travel and intake swirl.

    Angle mill up to 1 degree (about .110 off the exhaust side, .000 off intake side) safely for about 12 to 1 CR with flat pistons with little valve relief. Angle mill to 2 degrees (about .200 off exhaust side)if you like to live on the edge, it has been done.

    Larger valves increase flow, chamber mods not needed, trade off between shrouded verses unshrouded valves not worth the decrease in laminar flow and swirl.

    Throat cutting behind larger valves compliments the larger valves. Open the throat to the seat, remove the edge left by the cutter in the port.

    Blend the seats into the chamber, you don't want an edge here to disrupt flow and create turbulence.

    "Bowl blend" and shortened guide in port also improves flow. Taper and blend the iron boss.

    Minumal porting increases flow, too much increase in port size or loss of the benefits of the shape of the stock port will decrease efficiency.

    Vortec heads (and most others) like straight stemmed valves. Undercut valves create unwanted turbulence and a decrease in intake charge velocity (they add volume (slowing the gases)to the overall "port" volume just behind the valve where max velocity is required.)

    Generally speaking, Vortec's stall at between .500 and .550 valve lift. This is where flow actually begins to decrease. But their true strength is low lift flow which gives more area under the total flow curve. And if you think about it how long are your valves at peak lift? They spend much more time at .400 and below, where the Vortecs outperform most other heads. This combined with high velocity, lack of turbulence and superior combustion chamber design are where the Vortecs stand out.

    Unported, with all the other tricks in place, the Vortecs will flow about 235-240 CFM at .500 I and 165-170 cfm at .500 E, on a 4" bore at 28" H2O, with clay radiused port opening. With some careful porting there is another 5-10 CFM or so to be had. But again the low lift numbers are unsurpassed at .100, .200, .300, etc. lift. For example the Vortecs flow as much air at .400 as .500 and no 23 degree head that I'm aware of can match them at .200-.300 lift for the combination of flow and swirl. Even the Fast Burn head can't touch them at low lift, it's ports are too big (flow is similar, swirl is less), it does of course out perform them at lift over .500.

    Unported Vortecs with the "tricks" can produce 500 HP on well built, high CR, drag race short block. 425-450 HP is more realistic for a killer street engine running on pump gas."
     
  10. pdq67

    pdq67 BANNED

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    Jul 26, 2001
    Columbia, MO, USA
    Dirt,

    As always, thanks for sharing!!

    pdq67
     

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