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Thread: Head Flow Sheet for CNC'd Heads

  1. #1

    Default Head Flow Sheet for CNC'd Heads

    Are heads flow checked after they are ported? I asked for a flow sheet on my LT1 heads and recent set of LT4 heads. The information I received on the LT1 heads was adequate after requesting it. I did not get a flow sheet.

    I emailed numerous times for flow numbers on my LT4 heads that were supposed to flow good up to .650 lift and finally got a response. Here are the numbers I received.

    ".600 valve lift 88% on 300 scale 88x3.00 264 cfm intake

    .600 valve lift 65% on 316 scale 65x3.16 205 cfm exhaust"

    What am I missing here? They are supposed to flow to .650, I don't get it.
    These are lower numbers than my LT1 heads.

    I know you guys are busy, but can't you supply a flow sheet with a pair of heads? I realize I'm not spending 20 grand a pop, but I have still spent a good chunk of money with your company because of John Lingenfelter's legacy.

    My engine builder will be asking me for more numbers for cam grinding. More information would sure be nice.

    My invoice number is 3816.

    Regards

  2. #2

    Default Lingenfelter LT4 Cylinder Head Flow Numbers

    Because our cylinder heads are CNC ported we only flow test the original master cylinder head that we digitized to make our CNC porting program. After the master is made every head will turn out the same given the same valve size.

    Here is what our LT4 heads flow with a 2.00" / 1.56" valve size like your cylinder heads have.

    .600 valve lift 92% on 300 scale 276 cfm intake
    .650 valve lift 93.5% on 300 scale 280.5 cfm intake
    .600 valve lift 67.5% on 316 scale 213 cfm exhaust
    .650 valve lift 68.5% on 316 scale 216.4 cfm exhaust

    The numbers you posted would have been for LT1 cylinder heads. Please let me know if you need anything else.

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