Spring pressure ?

Discussion in 'PSI Superchargers Tech Questions' started by PROMOD63, Aug 2, 2011.

  1. PROMOD63

    PROMOD63 Member

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    I know it has been done to death but i have searched and cannot find any info on the effect of low intake spring pressure ? I have been fiting a flutter in my boost and have checked and rechecked all the obvious stuff but what if i was unseating the intke valve because of low spring pressure would this dump boost into a open cylinder and cause a flutter ?
     
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  2. badbird

    badbird New Member

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    if your blowing the valve off the seat with boost can you tell me what blower you have and who prepped it cause i want one,

    I know boost presure on the back of the valve has to be concidered when specing a spring pressure but if your springs are so low the pressure blows the valve open id say your in trouble or have the best blower ever,

    if you run a legal valve you probably have around 4.5 inches of area so if you have 40 psi boost you have about 180 lbs of pressure pushing against the back of your valve and that goes up at 50 psi 225 lbs of presure ect ect and so your valve spring pressure would have to be at or below these numbers for the valve to blow off and thats not lightly...is it?

    im sure someone will prove im wrong........;)
     
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    Last edited: Aug 3, 2011
  3. PROMOD63

    PROMOD63 Member

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    I wont be able to tell you for sure till i get it back together but i had two springs that had went from 460lbs to 375 and 325 i dont know why but i bet you a cold coke that when i get new springs on it the flutter will be gone
     
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  4. Mike Canter

    Mike Canter Top Dragster
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    My bet would be on the cam lobe ramp being so steep that the lifter roller can't stay on it so it is bouncing just a little on let down and showing up as flutter. High spring pressures help some to hold the lifter roller on the lobe but not always successful
     
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  5. badbird

    badbird New Member

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    i recently had some spintron testing done courtesy of jamie at NRE
    when we had this situation on the spintron heavier springs just moved the problem around and diddnt cure much at all, its amazing that the lifter with 600 lb spring presure can launch of the top of the lobe and miss the down ramp completly landing on the base circle that was down to valve weight...
     
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  6. Mike Canter

    Mike Canter Top Dragster
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    Call Noel Manton about his new came with a special profile that stops the bounce on let down
     
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  7. PROMOD63

    PROMOD63 Member

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    talked to noel today he said i had way too little spring pressure so i am going to try stiffer spring first then if this dont fix it ill go with his cam
     
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