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Thread: 706 to 241

  1. #1
    Join Date
    Feb 2010
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    Bowling green KY
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    706 to 241

    How much do 241s need to be milled to maintain the same compression as the stock 706 heads?
    04 rcsb with a few additions.

  2. #2
    Join Date
    Nov 2007
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    Pittsburgh, PA
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    you wont gain anything but a loss in wallet. the 5.3 heads flow same as the stock ls1 heads do
    2002 Lightning - GT headed 5.5Litre w/ Twin 7665s
    2002 Silverado - 427Lsx w/ Twin gt4202s
    2010 Silverado crewcab Z71 - 5.3litre w/ procharger
    2000 Wrangler - 5.3litre with some stance
    2014 Xsport- 3.5 Eco boost
    412 Motorsports

    it ain't that I'm too big to listen to the rumors, It's just that I'm too damn big to pay attention to 'em..That's the difference

  3. #3
    Join Date
    Jul 2009
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    532
    243's flow little more and have different springs and lighter valves

    +1 on Quick's word's of wisdom (on the 241's)

    And if your heads flow more cfm than is needed you will be losing and hp across the board. The idea is to keep the velocity of the air up. When you lose velocity you lose average hp and torque. So since your basically stock you can just get your heads short turn radius's changed a little (intake and exhaust) and will increase airflow and velocity for cheap. some call it a ball job i believe??
    Last edited by Tank; 03-22-2010 at 02:06 PM.
    04 Silverado Z-71 Extended Cab

    Magnaflow, 10.4 TV 50 wires, tr-55ix, Synthetics, HID's, JL audio, 33.5", leveling kit, tuned, CAI, vette servo, cam, valve job, pacesetter. 9.3@77.5 and 14.5@93.4

    06 2wd

    custom cam, tune, 3.73's, servo, HID's, 10.4mm wires, long-tubes, CAI, magnaflow, 2.5" shackles, Circle-D 3200, UD, JL Audio 4.1, Alpine 5ch

  4. #4
    Join Date
    Jul 2009
    Posts
    532
    ... air can't see.. but its got a hell of a feel
    04 Silverado Z-71 Extended Cab

    Magnaflow, 10.4 TV 50 wires, tr-55ix, Synthetics, HID's, JL audio, 33.5", leveling kit, tuned, CAI, vette servo, cam, valve job, pacesetter. 9.3@77.5 and 14.5@93.4

    06 2wd

    custom cam, tune, 3.73's, servo, HID's, 10.4mm wires, long-tubes, CAI, magnaflow, 2.5" shackles, Circle-D 3200, UD, JL Audio 4.1, Alpine 5ch

  5. #5
    Join Date
    Nov 2007
    Location
    Pittsburgh, PA
    Posts
    3,581
    not all 243s have lighter valves. Only the LS6 243s have lighter and longer valves. the 243s the come on the other motors have teh standard 2.0 valve that come in other heads
    2002 Lightning - GT headed 5.5Litre w/ Twin 7665s
    2002 Silverado - 427Lsx w/ Twin gt4202s
    2010 Silverado crewcab Z71 - 5.3litre w/ procharger
    2000 Wrangler - 5.3litre with some stance
    2014 Xsport- 3.5 Eco boost
    412 Motorsports

    it ain't that I'm too big to listen to the rumors, It's just that I'm too damn big to pay attention to 'em..That's the difference

  6. #6
    Join Date
    Feb 2010
    Location
    Bowling green KY
    Posts
    54
    Oh im not looking for a HP increase. My 706 heads are cracked, just looking to replace them. Have a set of 241s with less then 20 miles I wanted to put on it.
    04 rcsb with a few additions.

  7. #7
    Join Date
    Apr 2009
    Location
    Evant,tx
    Posts
    305
    i got a set of 706 heads i pulled off a motor not shure the milage but look good just need to be cleaned. ill sell them if u want them

  8. #8
    Join Date
    Feb 2010
    Location
    Bowling green KY
    Posts
    54
    thanks man I'll keep you in mind.
    04 rcsb with a few additions.

  9. #9
    Join Date
    Apr 2009
    Location
    Evant,tx
    Posts
    305
    ya theres a general spec site that shows how much to shave down ill see if i can find it for ya

  10. #10
    Join Date
    Apr 2009
    Location
    Evant,tx
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    So you want to figure out how much to mill:

    It takes about .005" milling of the block deck to remove 1cc of volume. It takes .007" milling to remove 1cc from an LS1 head

    Simple Milling Math:

    You have a stock 66cc chamber and you want to get down to 63cc

    66-63 = 3. You have to remove 3cc's

    .007 x 3 = .021. So to get your 66cc chambers down to 63cc you'd have to mill ~.021.

    You can also do the reverse, say you want to mill a head .030 to figure out how many CC's that removes you take .030 / .007 = ~ 4.28. Milling a stock 5.7 head .030 puts your chamber at ~ 62.

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