Plenums

[Jeremy Gonyou]

I believe that there is a scientific answer for all this...but only the 
Germans truely know it.  AFAIK, it's all about the Helmholtz effect.  
Consider the intake air as a mass-spring system.  A pressure wave rebounding 
from a closed valve is the mass.  The volume of air in the plenum is the 
spring.  My understanding is that the plenum will be sized to best 
accomodate the Helmholtz effect, making sure that the pressure wave returns 
to an opening valve.  TPI is the name of the game, right?  *Tuned* port 
injection?

Jeremy


>I think that there is a point when the plenum can be too small for the air
>that the motor wants to pull @ WO.  if i am not mistaken this is why
>Lingenfelter made the box (super ram).  he was running a 383 in the silver
>state classic & he somehow figured out that @ speed the motor was sucking
>the plenum out of air & that by making a bigger box that it did not do that
>any more.  i would expect that w/forced induction this would not happen but
>in naturally aspirated it could.  comments?  is there something to this or
>was i caught up in the bigger is better, sales propaganda?
>
>Bob Wooten

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