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Thread: what is a reasonable reliable rpm for 572 4.5 by 4.5

  1. #1

    what is a reasonable reliable rpm for 572 4.5 by 4.5

    on a 572 bbc in a boat, what would be the top rpm to turn the motor to keep it reliable? It has 6.535 length rods and 4.5 stroke and 10.2 deck. I really need to add a little nitrous to get a little more power and need to turn 7000 rpm. Will the low rod stroke ratio take its toll at this rpm. This rpm is only obtained while running in a quarter mile and not for any length of time at all. Mainly on a drag run. Motor has ohio crank, and ohio i beam rods with arp 2000 rod bolts. Would it be wise to change the bolts to L-19 rod bolts? Compression is only 10-1.

  2. #2
    Senior Member MASTER BUILDER
    Join Date
    Dec 2005
    Location
    Rutherfordton North Carolina
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    192
    7000 would be a piston speed of 5250,thats pushing it for the parts you have.I would replace the rod bolts with custom age 625 at least,there a far better bolt.Bill
    Hendrens Racing Engines
    1310 U.S. Hwy 221 North
    Rutherfordton N.C. 28139
    828-286-0780 Bill, Steve, Mike
    www.hendrensracingengines.com

  3. #3
    Administrator RACING JUNKIE
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    572 with 6.535 in a 10.200 tall deck? Sounds to me son you got the wrong rods in this engine,because the math don't add up
    There Is 1 Thing Better Than Cubic Inches,,,More Of Them

  4. #4
    Junior Member JOURNEYMAN
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    kNOXVILLE,TN.
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    4.5 stroke,6.535 length rods with a piston with a 1.415 compression height gives you zero deck.Why won't it work ?

  5. #5
    Administrator RACING JUNKIE
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    It will work,but I'm not to accustomed to putting the pin that far down on the piston,my preference

    I just believe it gets a better ring stack and better piston control with the pin hight closer to the top JMHO
    Everyone does thing differently,I'd used the 6.7 rod or a custom aluminum
    to get a better deck hight is all
    There Is 1 Thing Better Than Cubic Inches,,,More Of Them

  6. #6
    Junior Member JOURNEYMAN
    Join Date
    Dec 2002
    Location
    kNOXVILLE,TN.
    Posts
    26
    I agree with you.I wouldn't use that short a rod in a 4.5 stroke but thats what he said he had.


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