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                                                                                                       October 9, 196 9
       TO - NAME                                                      DIVISION                PLANT/OFFICE
                                           DEPT    Special
                  H. P. Bruns                Vehicle Development       Engineering Office              Highland Park
       ,-rtOM - NAME                       DEPT.                      DIVISION                PLANT/OFFICE
                  W. P. Wright                   S&M Engineering             Space                     Huntsville

                  Automobile Hood Scoops and Cowl Scoop Tests

                          During the week of August 17, 1969, Engineering Car No. 046, a race version of
                  the 1968 Dodge Charger 500, was taken to Talladega International Speedway for the purpose
                  of collecting data for evaluation of hood and cowl scoops used for inducing carburetor inlet
                  air. This memo reports the results from those tests.

                          Two basic configurations were tested. The first configuration utilized the normal
                  air intake source in the car cowl area to feed the carburetor while the second configuration
                  used a specially designed flush hood scoop (called a N.A.C.A. inlet) to obtain carburetor
                  air. These two configurations are sketched in Figure 1.

                          Modifications to configuration 1 were made by the addition of several sized deflec­
                  tors mounted over the standard cowl intake as shown in Figure 2. Three pressures were
                  recorded in the carburetor intake area: static pressure (Ps), which was measured by
                   mounting a probe flush with the carburetor inlet wall; total pressure (PT), measured by
                  a probe facing directly into the intake air flow at the carburetor inlet and on a plane in
                   line with the static probe; and dynamic pressure (q), which was a physical summation of
                   PT and Ps (q = PT - Ps).

                           Total pressure (Pt) remained essentially insensitive to configuration changes,
                  having the following average values at noted engine RPM's.

                                              Engine RPM            PT (psig)

                                                 3700                 .130
                                                 4500                 .182
                                                 5200                 .231
                                                 6000                 .343

                   Table I lists the measured values of Pg and q at the various engine RPM's. Significant
                   fluctuations are noted in both Ps and q with no trends apparent. This phenomenon is
                   attributed to a variable throttle setting being required from one condition to the next to
                   achieve the desired nominal engine RPM value. Relocation of the static pressure mea­
                   suring point to the plenum area immediately preceeding the carburetor intake removed
                   much of the measured fluctuation of this pressure and to some degree established trends
                   in the data.

       110-7879 REV. 1-63
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