NHRA Addresses 2019's Plans to Fuel Teams

NHRA Addresses 2019's Plans to Fuel Teams

Comments

  • Tim CharletTim Charlet Senior Member
    edited November 2018
    In the letter it states, if mechanical changes are deemed necessary, at present we believe they would most likely be implemented in the order shown below (subject to change):

    1. Mandate a Spec inlet for all Superchargers
    A. 10” X 4.6” inlet size
    B. 45-degree angle from rear of inlet opening to top of bores for rotors

    So, am I reading this correct - essentially a restrictor plate? Or are they restricting the amount of air volume only?
  • TwostepTwostep Senior Member
    edited November 2018

    So, am I reading this correct - essentially a restrictor plate? Or are they restricting the amount of air volume only?

    Sounds to me like they're saying restrict the flow from the hat into the top of the supercharger, not the flow from the base of the supercharger into the intake manifold. Mechanically stifling that much pressure sounds like a potentially expensive and dangerous situation.
  • Yvonne*Yvonne* Super Moderator
    edited November 2018
    I don't see a quote from Hagan? He must've been unavailable for comment. :p
  • Roger GatesRoger Gates Senior Member
    edited November 2018
    Twostep wrote: »
    Sounds to me like they're saying restrict the flow from the hat into the top of the supercharger, not the flow from the base of the supercharger into the intake manifold. Mechanically stifling that much pressure sounds like a potentially expensive and dangerous situation.

    The discharge side of the blower is not nearly as large as the inlet size or the same shape. These blowers have "Dead" areas in a regular discharge opening because of the helix which screws the air in one direction. That is why they are now positioned where they are on the engine. Shutting off the dead area and redirecting the air will concentrate the flow into one spot and even out the pressure. Several different shapes are used including but not limited to a pie shape and a cavity in front of the rotors for pressure balance. More important than the opening size is the shape and the separator as well as the rear angle of the opening. They don't want the separator to extend below the base of the injector. The closer you can get that separator to the rotors (top & bottom) the more you get rid of the "turbulence" or the "tornado" which restricts inlet and exit flow. It is similar to having the "pent" or pyramid in the manifold which evens out the flow to the ports and stops turbulence there. In the less sophisticated "old days" we used to switch the upper and lower rotor on the 671's to even out the ports. When you have a way different amount of fuel going to certain ports (cylinders) to get your tune up it means you have a different amount of air to those cylinders which puts an uneven load on the crankshaft, shortening it's life as well as stress on the block. The whole package from the butterflies to the intake valve is engineered not only for power, but actually for longevity and reliability as well as cost. It looks possibly the rules makers might once again drive costs up with their "money saving" ideas.
  • HEMI_guyHEMI_guy Senior Member
    edited November 2018
    So, am I reading this correct - essentially a restrictor plate? Or are they restricting the amount of air volume only?



    Gee, where have we heard that idea before? I've been proposing a plate under hat for years whenever the discussion of slowing the cars down gas come up.
    they could also reduce the size of the butterflies in the hat too, but that would be stupid expensive.
  • TwostepTwostep Senior Member
    edited November 2018
    Thanks, Roger. I don't fully understand what you're saying, with pie-shaped separators and rear angles...I'd like to read your post while actually looking at a TF supercharger setup...but I get the general idea. I did understand the purpose of the setback blowers - more even air/fuel distribution - but now I understand more of what's actually going on in there, and why. Thanks. ;)

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