Page 2 - Combined_103_OCR

Results of Final Daytona Test of 1968-1/2 Race Car. Page 2.

Discussion (c ont1d)

The engine used in the Charger was a Nichels Engineering unit,
that replaced the Engine Laboratory unit that broke a connecting rod
the first day of the test. The weather conditions during this test
were quite similar to those of the two previous tests.

In addition to the handling improvement with the new front
spoiler, several other items were investigated for their effects on
car speed. For the 184.1 mph run the car was run with the standard
grille location, with the grille completely uncovered, with no screen­
ing. The under bumper air intake was completely closed. With the
grille remaining in the standard location but blocked with one layer
of 40 mesh screening and the under bumper opening open the speed of
the car was increased to 185.6 mph. Completely blocking the upper
grille except in front of the oil cooler increased the speed to 186.3
mph. This increase of 2.2 mph for a fully blocked vs. a fully open
grille is in line with the gains found in earlier testing with Car 046.
The cooling of this car with the grille completely blocked was not
satisfactory, although the cooling of the previous 1968-1/2 Charger was
satisfactory with all of the cooling air taken in under the bumper.
This may be due to different levels of heat rejection for the particular
engines used.

The car was tested with wheelcovers to simulate the .reinforced
wheels. As in the previous test of the 1968-1/2 Charger they had no
effect, although in previous tests with Car 046 the wheelcovers had
been worth 1.3 mph. The front fenders on Car 046 were very nearly
flush with the outside of the wheel, while both of the 1963-1/2 Chargers
have had the front fenders bulged clear of the tire. This bulging of
the front fenders has shown in Proving Ground tests to have a sub­
stantial effect on reducing the aerodynamic drag of the car, but
apparently makes the reinforced wheels ineffective. It is not known if
a greater drag reduction is obtained from the bulged front fenders or
from the reinforced wheels, but the fender bulging is allowed under the
NASCAR rules, while the reinforced wheels are not allowed.

out a r ear deck
In all of the above tests the Charger was run with
tailed, which
spoiler.' For one test a 1/4" high rear spoiler was ins
slowed the car down by about one mph, and made the car “rush" (under-
nd 1i ng rather
steer). The speed loss was due to the effect on the ha
f the c ar with
than to additional drag. Baker did not like the fool o
the rear spoiler, and has not been using one on his Cha rt is year,
It would normally be possible to eliminate the "pushing condi tion by
chassis changes, although this was not tried. Baker fe tha t the
o
addition of a spoiler on the rear deck of the Charger m the car
o
less stable in drafting conditions.