Anyone know the benefit of porting an LY6 engine's heads ? ?

Discussion in 'High Tech Retrofits' started by 70 gsconvt, Jun 5, 2011.

  1. 70 gsconvt

    70 gsconvt Veteran Member

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    Sep 30, 2009
    Wadsworth, OH
    Hi, I'm still looking at putting a modern engine into my car.

    I've been doing a lot of reading on the internet, but can't come up with an answer to this one: how much of a benefit it there to porting L92-style heads???

    The L92 heads come from the factory on LY6 engines. So if I get one of those, would I be better off spending my money on a stroker kit and get the cubes up to 408? Or should I go traditional and have port/bowl work done to the heads?

    Does anyone have any personal experience with this one?
     
  2. RICARDO1969

    RICARDO1969 Veteran Member Lifetime Gold Member

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    Waukesha WI
    you don't need to port and polish they flow like all hell bone stock.
     
  3. 70 gsconvt

    70 gsconvt Veteran Member

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    Sep 30, 2009
    Wadsworth, OH
    I know they will outflow most other factory heads. I'm just wondering if buying cnc'd ones and a proper shortblock would be better than just getting a LY6 and just stroking it to get the power I desire without having to spin the engine to 7000 rpm's. I've seen tests and it looks like they don't start making more power until around 4500 rpm's. And I read anothe article that said for a street engine, the cathedral-port heads would be better.
     
  4. Aceshigh

    Aceshigh Veteran Member Lifetime Gold Member

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    Boondocks
    Porting any head makes it flow better.
    The question is, IS IT NECESSARY??? No one here knows what you're trying to do. ;)
     
    Last edited: Jun 5, 2011
  5. 71RS/SS396

    71RS/SS396 Veteran Member

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    My engine builder did some testing on this and he told me to not waste the money on porting l-92 heads there's not enough to be gained to warrant the expense.
     
  6. JJFarmer

    JJFarmer Veteran Member

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    Jun 28, 2002
    Lenoir City, TN
    I was wondering the same thing. I just got my cam and springs and was about ready to put it together.
     
  7. 70 gsconvt

    70 gsconvt Veteran Member

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    Sep 30, 2009
    Wadsworth, OH
    I just got my latest issue of CarCraft. They had someone write in conerning this. Their opinion was that L92 heads do flow great, but only at .600 lift and up. And most street engines don't have cams that have that much lift. They suggested a pair of cnc'd cathedral port heads which would give better port velocity, and better torque. And the flow up top is near the L92's.

    The theory is sound. I'll have to do some more researching on this.

    As to what I'm looking for, I want the car to be able to run in the 11's at the track, but still have good street manners. I have it with my 462 cid Buick, and now I want it with a manual trans car. So I'm probably looking for an honest 500 hp at the crank.
     
  8. JAMMINJ007

    JAMMINJ007 Veteran Member

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    Dec 27, 2005
    Houston, Tx
    That is easily achieved with just a cam swap. Get an EPS custom grind and your there! Don't worry about the porting not enough to gain any thing significant. Mill the heads maybe .020 ti get the compression up to over 10:1 and custom grind EPS and you will be more than happy;)
     
  9. 70 gsconvt

    70 gsconvt Veteran Member

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    Sep 30, 2009
    Wadsworth, OH

    Are you talking with an LQ4/LQ9 and it's stock 317 heads? Or an LY6 with it's L92 heads?

    I looked up their web site and saw they have about 10 cams, but not a lot of info on them compared to other cam manufacturers. Maybe they're like to keep their secrets under wraps.
     
  10. Aceshigh

    Aceshigh Veteran Member Lifetime Gold Member

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    Apr 9, 2001
    Boondocks
    That's not correct.
    Go check flow #'s yourself VS cathedral port heads.

    They outflow cathedral port heads easily.
    Even CNC ported early Z06 heads. http://forums.corvetteforum.com/1553660921-post5.html
     
    Last edited: Jun 7, 2011

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