NHRA Pro Stock and spec heads

Discussion in 'The Comp Buzz' started by Jeremy Tanksley, Jul 29, 2013.

  1. Bob Book

    Bob Book Active Member

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    Rob - I've built several of theses engines and lowering RPM would absolutely lower the cost. It's real simple - spinning a 93 gram valve to 11,200 is going to create a few more problems than 10,500. My old A/D engine that only ran to 10,000 was a low dollar reliable engine - my new 10.800 engine - not so much.....
     
  2. Jon Hansen

    Jon Hansen Member

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    Again, wouldn't lowering the valve lift lower the RPM's the motor would make power ? And checking valve lift is simple, a dial indicator is all you'd need.
     
  3. Mark Lelchook

    Mark Lelchook Member

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    Jon, its not the lift that limits the RPM its more the duration and profile of the lobe, unless you limited it to a really really low lift.

    Mark Lelchook
    D/ED F/SA
     
  4. Jon Hansen

    Jon Hansen Member

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    So, what's really low lift to limit RPM for Pro Stock ?, .750, .650, .550 ??
     
  5. Mark Lelchook

    Mark Lelchook Member

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    Boy id say .750 would be pretty low. But then the R&D on the engine and heads would end up costing a ton of money to make it work around low lift, that would be a visous cycle. My stocker has a whopping .450 lift, but I must have a few hundred hours on the flowbench to make the heads work at that lift.

    Mark Lelchook
    D/ED F/SA
     
  6. Bob Book

    Bob Book Active Member

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    All an rpm limit would require is an MSD box - nothing else. It would require no more policing than is already done.
     
  7. Rob Harrison

    Rob Harrison Well-Known Member

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    " A 93 gram valve @ 11,200 " yikes , no wonder they are wrecking themselves , all of this on a 5/16 stem , out of control ( pardon the pun ) The common use of a sledge hammer to break the retainer free , might be an indication that the motor is in valve float . I just looked at some data from the torture years , a 75 gram valve is in trace float @ 10,200 with 320 on the seat .

    Put 520 on the seat , I guess the float zone goes up , but 20 grams on the valve throws the whole equation into another zone . The multiple valve engines are just that to maintain valve control with smaller lighter valves , the 93 gram valve is going to dictate the float range , not to mention the destruction zone........out of control .
     
  8. JSwartz3300

    JSwartz3300 New Member

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    This discussion about P/S is all well and good but maybe we need to worry about comp. Our numbers are going down and fast. How do we fix that?

    ________________________
    John Swartz 3300
     
  9. rognelson777

    rognelson777 Active Member

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    Take a look at superstock, many events have 2 races in the same weekend, 1 is class heads up, no breakout and the other is all run eliminator based on dial in. . , also if you are the only car in class in class eliminations, they put all single cars in class against all other single cars in class, they handicap stick cars against stick cars using the index and there is no breakout, 1st to the finish line. Would be interesting in comp, if you ran off all autos against all autos, handicap off of index with no index changes or permanent hits.

    Alot of Hemi Superstock racers show up to just run class, and do not run eliminations.

    What do you think?
     
  10. Craig Bourgeois

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    Ss/ah?

    Now there's an idea. Why not create a class
    In comp that all of the SS/AH cars could
    Run in comp? It wound raise Comp car counts,
    and with their new cylinder head rule maybe they
    would come over and run Comp? What do
    Y'all think?
     
  11. Mark Lelchook

    Mark Lelchook Member

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    Give em a fair index and bring em on in. Hell give my stocker an index and lll bring it in as well.

    Mark Lelchook
    D/ED F/SA
     
  12. Bob Book

    Bob Book Active Member

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    Sounds good to me.......
     
  13. JSwartz3300

    JSwartz3300 New Member

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    I like it!

    ________________________
    John Swartz 3300
     
  14. JSwartz3300

    JSwartz3300 New Member

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    I like it!

    ______________________________
    John Swartz 3300
     
  15. Clint Neff

    Clint Neff Well-Known Member

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    I like it as well.
     
  16. RonP

    RonP Member

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    That sounds like a good idea for the SS/AH additional to Comp.
    Almost a link to the old days of Modified !!
     
  17. JSwartz3300

    JSwartz3300 New Member

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    No change in the rules for them. Give them the option to run comp or SS.

    __________________
    John Swartz 3300
     
  18. Jeremy Tanksley

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    There's already a class that's perfect for them. A/SM and A/SMA. Your weight break is 7.5 lbs per cubic inch.
     
  19. Bob Book

    Bob Book Active Member

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    Still not an SS/AH - nowhere near the appeal.....
     
  20. JSwartz3300

    JSwartz3300 New Member

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    The rules for A/SM and SS/AH are not even close. If we really want them to run comp. we need the rules to be the same as they run now.

    ___________________________
    John Swartz 3300
     

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