Prediction
of
Dynamometer Power Absorption
to Simulate
Light Duty Vehicle Road Load
by
Glenn D. Thompson
April 1977
Notice
Technical support reports for regulatory action do not necessarily
represent the final EPA decision on regulatory issues. They are intended
to present a technical analysis of an issue and recommendations resulting
from the assumptions and constraints of that analysis. Agency policy
constraints or data received subsequent to the date of release of this
report may alter the recommendations reached. Readers are cautioned to
seek the latest analysis from EPA before using the information contained
herein .
Standards Development and Support Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Office of Air and Waste Mangement
U.S. Environmental Protection Agency
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ABSTRACT
When EPA vehicle exhaust emission tests or vehicle fuel consumption
measurements are performed on a chassis dynamometer, the dynamometer is
adjusted to simulate the road experience of the vehicle. Specifically,
if the dynamometer measurements are to accurately reflect on-road opera-
tion of the vehicle, the dynamometer must supply the appropriate road
load; that is, the force required to drive the vehicle on a level surface
as a function of the vehicle speed. Current Federal Exhaust Emission
Certification Test Procedures specify the dynamometer adjustment as a
function of the vehicle weight.
This report uses the dynamometer power absorption information from the
EPA technical support report, "Light Duty Vehicle Road Load Determination"
to develop equations for predicting the small twin roll dynamometer
power absorption necessary to simulate the road load of vehicles. The
equations are developed by proposing model equations to predict the
dynamometer power absorption, first based on vehicle weight, and then
based on the vehicle reference frontal area. Most EPA testing is
conducted on small twin roll dynamometers and most vehicles are now sold
with radial tires. Consequently the estimates of the small twin roll
dynamometer power absorption for vehicles equipped with radial ply tires
were used for evaluating the prediction systems. It is concluded that
the prediction model based on the vehicle reference frontal area is the
preferred approach.
The reference frontal area based prediction system is then improved by
separating vehicles into different classes and by including estimations
of the effects of the total frontal area of the vehicle protuberances.
This modified equation is proposed as the optimum equation to predict
the dynamometer power absorption within the constraints of the available
data, test equipment and desired simplicity. It is concluded that the
errors associated with this prediction system are twenty percent less
than the errors associated with a prediction system based on the vehicle
weight only.
In the final section bias constructed tires and single large roll
dynamometers are considered since these test conditions occasionally
occur. The equations for predicting the small twin roll dynamometer
power absorption for vehicles with bias tire construction and the equation
for predicting the power absorption for single large roll dynamometers
are presented. These equations are developed by incorporating correction
terms in the aerodynamic based equations for predicting the small twin
roll dynamometer power absorption for vehicles with radial tires. These
correction terms are dependent on the type of tire construction and are
proportional to the vehicle weight.
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I. Purpose
This report proposes an equation to predict the adjustment of a
small twin roll dynamometer to simulate the road experiences of light
duty vehicles. The purpose is to develop the optimum equation for
dynamometer power absorption prediction within the constraints of the
available data and the limitations of the present test equipment. This
report documents the data sources and decisions used in developing the
proposed equation.
II. Introduction
When vehicle exhaust emission tests or vehicle fuel consumption
measurements are performed on a chassis dynamometer, the dynamometer is
usually adjusted to simulate the road experience of the vehicle. Specifi-
cally the dynamometer must simulate the road load of the vehicle. In
this report the vehicle road load force is defined as the component of
force in the direction of vehicle motion which is exerted by the road on
the vehicle driving wheels. As defined, the road load force is the
force which propels the vehicle. In the standard case, when a vehicle
is moving with a constant velocity vector on a level surface, this force
is equal in magnitude to the sum of the rolling resistance and the
aerodynamic drag of the vehicle.
Historically, the dynamometer adjustment for light duty vehicle
emission certification tests, and fuel economy measurements, has been
specified in terms of the dynamometer absorption horsepower at a simu-
lated vehicle speed of 50 mph. This report considers methods of pre-
dicting the vehicle experience in terms of the road load power, pri-
marily because of the historical precidence of using power instead of
force.
III. Discussion
A previous technical support report, "Light Duty Vehicle Road Load
Determination" reported the results of road load force measurements
from sixty-four diverse light duty vehicles. The results of the pre-
vious report are repeated in Appendicies A and B of this report for
consistancy and clarity. Table 1 of Appendix A describes the test
vehicles, while Appendix B provides the coefficients of force versus
speed equations of the form:
F - fQ + fjV + f2v2 (1)
where
F = the force as a function of velocity
v = the vehicle velocity
f_, f1, f_ = the force coefficients
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Coefficients are presented for the total flat surface vehicle road load,
and for the appropriate dynamometer adjustments to simulate the vehicle
road experience on several types of dynamometers. Also included in
Appendix B is the computed dynamometer power absorption requirements to
simulate the road experience of each vehicle at 50 mph. The discussion
of the data collection and data analysis methods are described in the
referenced report and are not repeated.
This section will present models to predict the dynamometer power
absorption, first based on the vehicle weight and then based on the
vehicle reference frontal area as the prediction parameter. These
prediction models are compared and evaluated. Attempts are then made to
improve the reference frontal area based prediction system by separating
vehicles into different classes and by including estimates of the effects
of the vehicle protuberances.
The majority of tires sold in the U.S. are of radial ply construc-
tion, and the market predominance of the radial tire is increasing.
Approximately 75% of the original equipment tires on 1976 vehicles were
radials. Because of the predominance of the radial tire, particularly
for new vehicles, the estimates of the appropriate dynamometer adjust-
ment for vehicles with radial ply tires are used for all comparisons of
the dynamometer power prediction models.
A. Prediction Model Using Vehicle Weight as the Predictor of the
Dynamometer Power Absorption
A theoretically based model can be developed from several logical
assumptions. The first assumption is that, because of similarities in
manufacturing technology, the density of light duty vehicles is approxi-
mately constant . Stated as an equation, the assumption is:
W ^ V (2)
where
W = the weight of the vehicle
V = the volume of the vehicle
The vehicle volume is approximately equal to the product of the three
major dimensions. The second assumption is that each of the major
vehicle dimensions may be expected to increase approximately equally
with an increase in weight. Consequently each major dimension is pro-
portional to the cube root of the vehicle weight. That is:
L ^ W1/3 (3)
where
any of the major vehicle dimensions of height
width and length
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The total vehicle road load is the sum of the aerodynamic drag
forces and the vehicle rolling resistance. The major source of the
vehicle rolling resistance is the power dissipation in the tires.
4
One available reference discusses power dissipation of radial ply
tires on a small twin roll dynamometer. This reference indicated radial
ply tires, inflated to 45 psi, dissipate more than twice as much power
on a twin roll dynamometer as they dissipate on a flat surface. The
data presented indicated two radial ply tires inflated to 45 psi, dissi-
pate as much energy on a small twin roll dynamometer as four radial ply
tires inflated to 25 psi dissipate on a flat surface. This supports the
common assumption that two tires on the dynaomometer dissipate as much
power as four tires dissipate on the road. Therefore the dynamometer
power absorber primarily simulates the aerodynamic losses of the vehicle.
The aerodynamic drag is proportional to the vehicle reference
frontal area, which is approximately equal to the product of the vehicle
height and width. Consequently the twin roll dynamometer power absorption
should be proportional to the weight of the vehicle to the two-thirds
power.
P * W2/3 (4)
The previous arguments are hardly rigorous, therefore a model of
the form:
P = aW* (5)
was chosen which allowed the exponent to vary. This model will predict
a dynamometer power of zero for a vehicle of zero weight, which is
theoretically appropriate. Also, if x is less than 1, the model pre-
dicts the slope of the force versus weight curve will decrease as the
weight increases. This is also theoretically logical; and consistent
with the observed data.
Equation (5) was fitted to the data for the vehicle weight and the
estimated small twin roll dynamometer power absorption at 50 mph for
vehicles with radial ply tires. These data are presented in table 3
of Appendix B and are plotted in Figure 1. A generalized least squares
fitting method, using a Gauss-Newton interation algorithm was used.*
The results of this regression are:
*A report discussing the techniques used by EPA for non-linear curve-
fitting by the Generalized Least Squares Technique is being prepared.
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. 0 i • •
. n 'i n *
-<.'"' 0 i;
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-5-
« *•>> it
Figure 1
0 fn I
Regression of Twin Roll Dynamometer Power at 50 mph
for Vehicles With Radial Ply Tires
Versus
Vehicle Weight
Regression Model
P = aW31
P =» the dynamometer power absorbtion at 50 mph (horsepower)
W = the vehicle weight (pounds)
a - 0.253
x = 0.456
Sample size: 67
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The accuracy of the regression may be assesed by observing the
residuals between the regression line and each data point. These resi-
duals are plotted versus the vehicle identification number in Figure 2.
Figure 2 demonstrates the range of errors between the regression line
and the data points is about three horsepower. The standard deviation
of the residuals is about 1.2 horsepower, indicating that 68% of the
data points fall within +1.2 horsepower from the regression line.
of. sir.
-<, ^nc 0
. r n •;) n
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*
1-1 T/'.
Figure 2
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B. Prediction Models Using Aerodynamic Parameters to Predict
the Dynamometer Power Absorption
The model equation for the dynamometer power absorption prediction
was developed in the previous section using the argument that the
dynamometer power absorption simulated the vehicle aerodynamic losses,
and the assumption that the vehicle weight was an indirect predictor of
the aerodynamic drag. Theoretically a better prediction equation should
result if a parameter directly related to the vehicle aerodynamic drag
were used instead of the vehicle weight in the prediction equation. The
aerodynamic drag of a vehicle is given by:
faero ' I 'V^ (6)
where
p = the air density
C = the vehicle drag coefficient
A = the vehicle reference area
v = the vehicle velocity.
The reference area of equation (6) is the area of the orthogonal projec-
tion of the vehicle onto a plane perpendicular to the longitudinal axis
of the vehicle. This is commonly called the frontal area in aircraft
aerodynamics however, the7term reference area has been adopted in the
road vehicle literature ' possibly because of confusion with the front
surface of the vehicle.
The power is, of course, the product of the force and the velocity.
Therefore, for a fixed standard-condition air density, the power at any
speed is proportional to the product of the drag coefficient and the
vehicle reference area, that is:
P ^ CDA (7)
The drag coefficient, C , is not commonly known and is difficult to
accurately estimate. Consequently the easiest aerodynamic parameter to
consider is the vehicle reference area.
1. Prediction System Based on Vehicle Reference Area Only
Equation (7) indicates that the vehicle dynamometer power absorp-
tion should increase linearly with the vehicle reference area. The
power versus reference area data are plotted in Figure 3. This plot
indicates a linear fit appears reasonable.
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14.01)0
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T. 00
* ---- *
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Figure 3
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A linear regression of this form was computed using reference area data
supplied by the vehicle manufacturers. The results of this regression
are:
Regression of Twin Roll Dynamometer Power at 50 mph
for Vehicles with Radial Ply Tires
Versus
Vehicle Reference Area
Regression Model
P = aA
P = the dynamometer power absorbtion at 50 mph
A = the vehicle reference area
a = 0.50
Estimate of the Standard Error =1.1
Sample Size: 67
In order to provide comparisons between this regression and the
previous weight-based regression, the residuals of the area regression
are plotted in Figure 4. The maximum error between the regression line
and any data point is about 2.5 horsepower. The estimate of the standard
error which is equivalent to one standard deviation of the residuals is
about 1.1 horsepower, indicating that 68% of the data lies within +1.1
horsepower of the regression lines.
The residuals of the area regression are 10 percent smaller than
those from the weight based regression. This indicates that, as theor-
tically expected, the vehicle reference area is a better predictor of
the appropriate dynamometer adjustment than is the vehicle weight. _
Evidence supporting this conclusion was reported by General Motors.
2. Prediction System Using Both Vehicle Reference Area
and Vehicle Classes
The results of the reference area regression establishes that aero-
dynamic parameters are the preferred approach to predicting the dynamo-
meter power absorption. It is therefore logical to consider what
improvements, beyond the use of vehicle reference area are possible
within this theoretical framework. Equation (7) demonstrates the true
theoretical predictor of the dynamometer power absorption should be the
product of the vehicle reference area and its drag coefficient. Utilizing
the vehicle reference area only, in effect, assumes that all vehicles
have equal drag coefficients. Vehicles have significantly different
drag coefficients, therefore incorporation of methods to estimate the
vehicle drag coefficient should improve the accuracy of the power pre-
diction system.
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, Figure 4
Several attempts have been made to develop systems to predict
vehicle drag coefficients. ' ' While good accuracy has been claimed
for some of these systems, all are rather complex. In addition they are
somewhat subjective, which is objectionable for a regulatory process.
For these reasons a simpler approach of dividing vehicles into several
classes was considered. While being corser in nature, this approach is
much easier to quantify, and should remove some of the inequity of using
the vehicle reference area only. This approach was used in the Light
Duty Truck Regulation, where trucks were divided into the categories of
open and closed bed vehicles for the purpose of determining the dynamo-
meter power absorption.
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For light duty vehicles, an initial attempt was made to categorize
vehicles as having aerodynamically "good" versus "bad" fore and aft body
shapes.
Categorization of the fore body shape requires consideration of the
details of several body regions. For example, the angle of the hood-
windshield transition region, the curvature of the vehicle front to hood
region, and the curvature of the front to side transitions. The wind-
shield angle, its curvature, and its transition to the roof surface and
the vehicle side surfaces also affect the drag of the vehicle fore body
region. While it may be possible to quantify the criteria for these
individual areas, and to develop a composite rating system; such an
approach would be complex. An approach similar to this was proposed in
the September Federal Register. The comments to this proposal were
negative, at least partially because of the complexity and the sub-
jectivity of this method. Consequently further consideration of the
vehicle fore body region was not considered at this time.
Consideration of the aft body region of the vehicle was more suc-
cessful, primarily because a general vehicle shape could be recognized
as "good". To reduce aerodynamic drag, the vehicle body should delay
flow separation, and should reduce the area of the vehicle acted upon by
the low pressure wake. In general, vehicles commonly called "fastback"
models meet these objectives. A sketch of a "fastback" model is shown
in Figure 5.
SIDE VIEW
r
REAR VIEW
Figure 5
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The aerodynamic literature provides several criteria for "good" aft
body shapes which can be used to define quantitatively a fastback
model. In general, aft of the maximum cross section of the vehicle
there is a viscous boundary layer of increasing thickness. Associated
with this boundary layer is a pressure gradient which, if it becomes
sufficiently large, will cause flow stagnation and separation. To avoid
flow separation at some local region forward of the end of the vehicle,
any inclined aft body surfaces must be smooth and continuous. It is
believed that local declinations of the surface should not exceed three
to five degrees from the airstream .
The literature also indicates the general angle of declination of
the inclined rear body surfaces affect the aerodynamic drag of the aft
region. An angle of declination of 20 degrees appears to be a critical
angle for transition of the aerodynamic flow into different general
types of aerodynamic behavior. When the angle of declination of the
inclined surface is less than 20 degrees, the contribution to the
vehicle drag coefficient from this surface increases as the angle
increases. At an angle of declination of 20 degrees the drag contri-
bution from this surface is approximately equal to the drag contribution
from a vertical rear surface of the same reference area. Beyond a
declination angle of 20 degrees the drag coefficient contribution con-
tinues to increase with increasing angle, until it peaks at about 30
degrees. Between 30 degrees and 35 degrees the drag contribution
decreases with increasing angle until, at approximtely 35 degrees, the
contribution is again the same as a verticle rear surface. It remains
at this value for any further increase in the angle.
The continuity and angle criteria define the conditions believed
necessary for low aerodynamic drag of the inclined rear body surfaces.
If this region is to have a significant effect on the total aerodynamic
drag of the vehicle, the inclined rear body surfaces must contribute
some significant percentage of the total rearward projected area of the
vehicle. A choice of significant area is somewhat arbitrary since,
unlike the angle criterion, there is no critical value. Observation of
vehicles generally described as fastbacks indicated that at least one
fourth of the vehicle rear projected area resulted from this inclined
surface. This is almost essential to assure reasonable rear visibility
since the rear window is contained in this surface and its size is
constrained by the available surface area.
From these theoretical and empirical considerations, a fastback was
tentatively defined as a vehicle where the inclined rear body surface is
smooth, continuous and free of any local transitions of greater than A
degrees. In addition, this surface must slope at an angle of 20 degrees
or less from the horizontal; and the rearward projected area of this
surface must comprise at least 25 percent of the total vehicle reference.
area. For example, vehicles of the type shown in Figure 5 were considered
fastback models if 0 < 20° and A, ^0.25 A.
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Vehicles of the shape shown in Figure 6 were not considered as
fastback models even if the rear window region did slope at an angle of
20 degrees or less since; these vehicles were not deemed to meet the
criteria of a smooth and continuous surface with local transitions of
less than 4 degrees.
SIDE VIEW
Figure 6
After choosing a set of criteria for defining a fastback vehicle,
the logical step is to ascertain which of the test vehicles satisfied
these criteria, and then to test if the appropriate dynamometer power
absorption for these vehicles is statistically different from that of
the remaining vehicles. To identify potential fastback vehicles, side
view photographs of all the test vehicles were reviewed and those vehicles
which appeared to meet the criteria were identified. Measurements were
then obtained from these vehicles. The angles of the inclined rear body
surfaces were obtained directly from the vehicles using an adjustable
triangle and level. The projected reference area of this surface was
estimated by measuring the horizontal dimension of the top and bottom of
this surface, and then the verticle separation between the points of
these measurements. The estimated area was then calculated by a trape-
zoidal approximation. The list of these vehicles and their measurements
are given in Table 1 of Appendix C. Those vehicles which satisfied the
fastback criteria are identified in this table.
In order to evaluate if the fastback vehicles did actually have
lower aerodynamic drag than other vheicle shapes, a "drag coefficient"
was computed from the calculated dynamometer power adjustment. The
equation used to compute the "drag coefficient" was:
CD = Hp/.81 A (8)
where
Hp = the dynamometer adjustment power (horsepower)
A = the vehicle reference area (ft )
.81 = a units conversion factor including the density of air.
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In equation (8) the constant term, 0.81, differs slightly from the more
common value of 0.85. This results from using 1.16 kg/m as the standard
air density. This air density corresponds to the chosen standard condi-
tions of the EPA Recommended Practice for Road Load Determination.
These ambient conditions are:
temperature 20°C (68°F)
barametric pressure 98 kPa (29.02 in Hg)
humidity 10 gm H20/kg dry air.
These standard conditions were used in the ambient air condition
corrections to the original data and were chosen as typical of the Ann
Arbor-Detroit area. The coefficient value of 0.85 results if sea level
conditions are chosen as the standard ambient conditions.
The resulting C ' s are presumed to be a reasonable relative measure
of the aerodynamic drag of vehicles, however these numbers may not
exactly agree with wind tunnel measurements of aerodynamic drag coef-
ficients. For exact agreement, the assumption that two tires on the
dynamometer dissipate as much power as four tires dissipate on the road,
must be exactly correct. Also since some cross wind was present during
most road tests, these coefficients are not directly comparable to wind
tunnel data at zero aerodynamic yaw conditions. The resulting coeffi-
cients are presented in Table 3 of Appendix C, as is fastback or non-
fastback designation of the vehicle. An analysis of variance was per-
formed on these drag coefficients after separation into fastback and
non-fastback categories. The results of this analysis are:
Analysis of Variance of Computed Drag Coefficients
Mean Std. Dev. Sample Size
Fastback 0.53 0.045 7
Non-fastback 0.62 0.062 60
A "Student's test" of the hypothesis that the mean C of the
fastback vehicles is less than the mean Cn of the non-fastback vehicles
indicates, with over 99% confidence, that this hypothesis cannot be
rejected.
A visual observation of the calculated drag coefficients confirms
the statistical results. A computed drag coefficient of 0.52 is the
approximate demarcation between fastback and non-fastback vehicles. Of
all the non-fastback vehicles only one, an AMC Pacer has a computed drag
coefficient significantly lower than 0.52. The low drag coefficient of
the Pacer, 0.50, probably results from the well rounded front of this
vehicle. Conversely the two Ford Mustangs with computed drag coefficients
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of 0.57 and 0.60 are the only fastback vehicles where the computed drag
coefficients were significantly greater than 0.52. It should be noted
that these vehicles had a rear surface declination angle of 20 degrees,
the maximum allowable angle under the chosen criteria for fastback
vehicles.
3. Protuberances
Treatment of vehicle protuberances were considered as a final
improvement of the aerodynamic based dynamometer adjustment prediction
system. Vehicle protuberances were addressed in September 10, 1976
NPRMi The comments were generally negative; raising the following
objections:
1) A great proliferation of very similar dynamometer adjustments
would occur because of minor changes in accessories.
2) Most protuberances have a. small effect on the vehicle aero-
dynamic drag.
To eliminate the necessity of considering all small protuberances such
as radio aerials individually, a system which considered only the total
area of all protuberances was investigated. Also, in order to avoid the
large proliferation of dynaometer adjustments, the approach of using
discrete protuberance area categories was chosen. This is similar to
the current treatment of vehicle inertia. The incremental vehicle drag
caused by a vehicle protuberance can be theoretically predicted as equal
to the aerodynamic drag of the protuberance object. This neglects the
interaction of the vehicle and the protuberance. For such protuberances
the aerodynamic drag may be predicted by:
f = \ p (1.1)A (9)
3
Assuming an air density of 1.16 kg/m , and converting to units of horse-
power, equation (9) becomes:
Hp = 0.89 A (10)
P P
where
Hp = the incremental power required by the
vehicle protuberance (horsepower)
A = the protuberances area in ft .
P
In a system of units convenient for the small size of most protuberances:
Hp = 957 A niv
*p pern (11)
2
A = the area of the protuberance in cm .
pern
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In order to investigate the relative effect of common vehicle protuber-
ances; mirrors, aerials, hood ornaments, and roof racks; the area of
these protuberances were measured from a small diverse group of vehicles.
The summaries of these data, computed to the nearest square centimeter,
are:
Area Area Area Sample
(cm ) (cm ) (cm ) Size
Hood ornament 19 29 6 11
Aerial 38 42 38 13
Mirror 117 135 81 12
Roof rack 194 237 166 9
From equation (11) the incremental horsepower anticipated for each
protuberance, based on the mean area is:
Incremental Power
(horsepower)
Hood ornament 0.018
Aerial 0.036
Mirror 0.112
Roof Rack 0.184
Comments to the Fuel Economy NPRM by vehicle manufacturers included
estimates of the power losses incurred by vehicle protuberances. Chrysler
estimated the effect of an antenna at 50 mph as 0.1 hp, a hood ornament
as 0.15 hp, and mirrors between 0.1 and 0.3 hp. Chrysler also reported
measured values of .315 hp for the effect of a stationwagon roof rack at
50 mph. In approximate agreement with the Chrysler values, GM estimates
the aerodynamic effect of a stationwagon roof rack as approximately 0.55
to 1.0 hp at 50 mph. Available wind tunnel data from one vehicle
indicates the effect of a roof rack is 0.33 hp while the combined effect
of a roof rack and rear air deflector is 0.8 hp. EPA coast down measure-
ments on a vehicle with a roof rack and air deflector, versus a vehicle
which was the same model without these devices indicated an effect of
about 1.0 hp at 50 mph.
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The empirical data indicate the power penalty for vehicle protu-
berances is greater than the calculated values. -Much of these differ-
ences occur because the dynamic pressure, 1/2 pv , may be significantly
higher at the protuberance site, than calculated from the free stream
flow. Also items such as a roof rack have numerous verticle posts and
cross bars which offer greater total air resistance than is estimated
from the projected reference area of the device.
The incremental effects of the hood ornaments, aerials and mirrors
are all small; and the effect of each is probably within the experi-
mental error of normal road load measurements. Also the expected tol-
erance in the dyanomometer adjustment exceeds the effect of these small
protuberances. The effect of the roof rack appears significant, and the
combined effect of all protuberances is significant if the vehicle is
equipped with a roof rack.
The following system of discrete steps was developed to avoid the
problems associated with considering all vehicle protuberances indivi-
dually, and still retain the ability to treat numerous or significantly
large protuberances.
Since all vehicles have at least one external mirror, and the
majority also have an external aerial, the minimum anticipated protub-
erance reference area is 150 cm . Therefore to allow the possibility of
desirable safety options, such as a second mirror, within a standard
vehicle protuberance-reference area category, a demarcation point of
approximately 280 cm or 0.3 ft was chosen. In the EPA test fleet 40
percent of the vehicles had a second external mirror, 60 percent had
external aerials and 24 percent had hood ornaments. Consequently the
"average" vehicle had a protuberance area of about-192 cm . The demar-
cation point of 280 cm allows an additional 88 cm increase above the
computed average protuberance area before a vehicle is considered to be
in a category of greater than average protuberance area. This tolerance
will provide manufacturers flexibility in choosing larger than average
mirrors, since this demarcation point allows a manufacturer to equip a
vehicle with two of the largest measured mirrors, and still be within
the average vehicle category.
A table was constructed by considering the total vehicle protu-
berance reference area in increments of 0.3 ft . Below the total protu-
berance reference area demarcation point of 0.3 ft no additional dyna-
mometer power adjustment penalty was assumed. In the interval between
0.3 ft and 0.6 ft the midpoint is 0.45 ft . The horsepower penalty
for the midpoint area is, from equation (10), 0.4 hp. For a vehicle to
fall in this category it would most likely be equipped with a roof rack
only. This horsepower penalty is consistent with the data reported by
manufacturers of between 0.315 hp and 0.55 hp.
2 2
A similar approach was taken for the 0.6 ft and 0.9 ft interval.
The midpoint is 0.75 ft with a calculated effect of 0.7 hp. For the
interval 0.9 to 1.2 ft , the midpoint is 1.05 ft with a calculated
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effect of 1.0 hp. For a vehicle to have this large a protuberance
reference area, it would have to be equipped with both a roof rack and
an air deflector. In this case, the 1.0 hp is also consistent with
empirical data.. The table was extended by considering further incre-
ments of 0.3 ft in the protuberance reference area in the same manner.
Table 1 gives the complete tabulation of total protuberance reference
area versus the dynamometer power adjustment.
Table 1
Total Protuberance Reference Power Adjustment,
Area, A (ft ) P (hp)
A < 0.3 0.0
0.3 <_ AP < 0.6 - 0.4
0.6 <. AP < 0.9 0.7
0.9 <_ AP < 1.2 1.0
1.2 <_ AP < 1.5 1.3
1.5 1 AP < 1.8 . 1.6
1.8 <_ Ap < 2.1 1.9
2.1 <. AP < 2.4 2.2
2.4 <_ AP < 2.7 2.5
2.7 <_ AP < 3.0 2.8
3.0 < AP 3.1
- P
It should be noted that the previous theoretical discussion may
somewhat over estimate the effect of mirrors since external mirrors are
often "bullet" shaped or located in regions of separated aerodynamic
flow. The effect of mirrors is correctly treated in the analysis since
they are not included in the measurements of vehicle reference area, nor
is any additional horsepower prescribed for these small probuterances.
The effect of these protuberances will appear as a higher apparent drag
of the vehicle as measured, and as included in the basic regression
calculations.
The final composite equation to predict the dynamometer power
absorption as a function of vehicle reference area, vehicle type and
vehicle protuberance reference areas is:
Hp = aA + P (12)
where
Hp = the dynamometer power adjustment for vehicles with
radial ply tires (horsepower) »
A = the vehicle reference area (ft )
P = the proturberance power term from table 1 (horsepower)
a = a constant which has different values for fastback
and non-fastback vehicles.
-------
-19-
The coefficients, a, of equation (12) are determined from regression
analyses after separating the sample space into the subsets of fastback
vehicles, non-fastback vehicles without roof racks and non-fastback
vehicles with roof racks. The equation is then evaluated by calculating
the predicted dynamometer adjustment power from equation (12) using the
appropriate value of the coefficient, a, for each type of vehicle and
the estimated protuberance power, P, for each vehicle. The residuals,
the differences between the measured and the predicted dynamometer power
absorption, are then calculated. These residuals are then compared to
the residuals of the previous prediction systems to evaluate this predic
tion equation.
The fastback vehicles have already been identified in Table 1 of
Appendix C. The vehicles with roof racks were also identified from the
vehicle photographs. The area of the protuberances of the vehicles were
estimated, and the resulting horsepower increment at 50 mph was chosen
from Table 1 of this report. This information is given in Table 3 of
Appendix C.
Table 4 of Appendix C identifies each vehicle as either a fastback,
non-fastback or non-fastback with roof rack. Also presented in Table 4
is the vehicle area and the dynamometer power absorption.
The dynamometer power absorption was first regressed against the
reference area of the fastback vehicles only. The results of this
regression are:
Regression of Dynamometer Power Adjustment for
Vehicles with Radial Tires
Versus
Reference Area of Fastback Vehicles
Model Equation Hp = a.A,.
J. I SLS t
where
Hp = the dynamometer power adjustment (horsepower)
A. = the^Ref erence Area for Fastback Vehicles
fast
a^ = 0.43
Estimate of the standard error = 0.70
Sample size = 7
In order to determine the area coefficient for non-fastback vehicles,
the dynamometer power absorption for those non-fastback vehicles not
equipped with a roof rack were regressed against the vehicle reference
area. Removal of the vehicles with roof racks from the sample was
necessary in order not to penalize all non-fastback vehicles by including
the adverse effects of the roof rack in the general non-fastback regression.
The results of this regression are:
-------
-20-
Regression of Dynamometer Power Adjustment
for Vehicles with Radial Tires
Versus
Reference Area of Non-Fastback Vehicles
Model Equation Hp - a_A c .
^ r 2 non-fast
where
Hp = the dynamometer power adjustment (horsepower) .
A , . - the Reference Area for Non-Fastback Vehicles (ft )
non-fast
a = 0.50
Estimate of the Standard Error =1.0
Sample Size = 56
Equation (12) can now be used to predict the total dynamometer
power adjustment for all vehicles in the test sample, using the coeffi-
cients of the previous regressions. The predicted powers are given in
Table 4 of Appendix C.
The residuals between the predicted and the measured powers are
plotted in Figure 7. The maximum error is about +2.8 to -2.0 horsepower
and the standard deviation of these residuals is approximately 1.0
horsepower. This is a ten percent reduction in the standard error
compared to the prediction system based on vehicle reference area only.
It is, as expected, a significant improvement of twenty percent reduc-
tion in the standard error compared to the weight based prediction
system.
C. Tires
The previous sections developed an optimum equation to predict the
small twin roll dynamometer power absorption for vehicles with radial
tires. This is definitely the most common test situation, however,
other dynamometers and tires are used and these test conditions must be
considered. Radial tires are recognized to have lower rolling resistance
than do bias ply tires on a flat road surface, yet the radial tire does
not have appreciably lower rolling resistance on the twin roll dynamometer.
Therefore it is desirable to develop a tire type correction term, so
that the bias ply tired vehicles are not under-loaded during small twin
roll dynamometer tests.
The rolling resistance of a tire is very nearly proportional to the
verticle load force on the tire. Therefore the vehicle weight is the
logical parameter to use to predict the tire type correction term.
Assuming the tire losses are proportional to the vehicle weight, the
tire type correction term should have the form:
Tp = cW (13)
-------
-21-
RESIOUAL
5.0000 *
3.0000 *
* *
1.0000 * « « * » * 2
« « «
« » « «» «*
• * «»«» » » »«* «* *
» » * «» «
»« # 2 * ** 2 2
•1.0000 » • * »
« « « *
-3.0000 *
•5.0000 *
101 3701 7301 ID
1901 5501 9101
Figure 7
-------
-22-
where
T = the tire type power correction term (horsepower)
cp = zero for radial tire and a constant for bias ply tires
or bias-belted tires
W = the vehicle weight (pounds)
The coefficient, c, was determined by regressing equation (13) against
the differences between the small twin roll dynamometer power absorption
for vehicles with bias ply tires, Table 2 of Appendix B, and the small
twin roll dynamometer power absorption for vehicles with radial ply
tires, Table 3 of Appendix B.. The value of the coefficient from this
regression is: c = 2.3 x 10
Analysis of the comments to the Fuel Economy NPRM indicate such a
coefficient is reasonable. Analysis of data submitted by General
Motors in response to the fuel economy NPRM indicate the coefficient
should be 3.75 x 10 .
-4
A coefficient of 3 x 10 was chosen as a compromise value. At the
present time the available data do not appear comprehensive enough to
allow specification of this coefficient to more than one significant
digit. While it would be desirable to be able to specify this coeffi-
cient more precisely, it should be recognized that even for a heavy 5000
Ib. vehicle, the total effect is only 1.5 hp. Changing the current
coefficient by one unit in the most significant digit will only affect
the predicted vehicle road load by 0.5 hp. In addition since radial
tires currently command almost 80 percent of the OEM market, the correc-
tion term will only be applied to a small percentage of the total EPA
test vehicle population.
When testing on a large single roll dynamometer the drive tires
dissipate significantly less power than is dissipated on a small twin
roll dynamometer. In this case the tire assumption "two tires on the
dynamometer dissipate as much as four tires dissipate on the road" is
invalid. Consequently a term must be added to the dynamometer power
absorption to compensate for the non-driving tire power dissipation
which occurs on the road, but not on the dynamometer.
A prediction model based on the vehicle weight was again chosen
because the rolling resistance of a tire is very nearly proportional to
the verticle load force on the tire. To maintain similarity to equation
(13), a model of the following type was chosen
D - dW + etW (14)
where
D = tire correction for large roll dynamometer power
absorption (horsepower)
W = the vehicle weight (pounds)
t = 0 for radial tires; 1 for bias tires.
d and e are coefficients to be determined.
-------
-23-
Table 2 of Appendix A gives the vehicl% weight and the tire types
when tested. Table A of Appendix B gives the calculated dynamometer
power absorption for testing on a large single roll dynamometer, while
Table 3 gives the dynamometer power absorption for testing vehicles with
radial ply tires on a small twin roll dynamometer. The differences
between these dynamometer absorptions represent the tire correction
necessary when testing on a large single roll dynamometer. A regression
analysis of the dynamometer power difference data was calculated to
yield the coefficients, d and e, of equation (14). The results of this
regression are:
Regression of Dynamometer Type
Power Correction
Versus
Vehicle Weight
Regression Model
D = (d + et)W
D = dynamometer type power correction (horsepower)
W = vehicle weight (pounds)
t = 0 for radial tires; 1 for bias tires
d - 5 x 1(TJ
e - 1 x 10
Estimate of the Standard Error =0.5
Sample Size = 67
The value of the coefficients in the above regression were rounded
to the nearest most significant digit. The variations in the data are
sufficiently large compared to the small size of the correction term
that further precision is not warranted.
No comments regarding the prediction of large roll dynamometer
adjustment forces were received in response to the Fuel Economy NPRM.
IV. Conclusions
It is concluded that vehicle aerodynamic parameters are the pre-
ferred predictors of the dynamometer power absorption. This approach
has a stronger physical science foundation and affords greater accuracy
than prediction systems based on the vehicle weight. The proposed
equation to predict the dynamometer power absorption using the vehicle
reference area, fastback and non-fastback vehicle categories, and consideration
of the total vehicle protuberance area has a standard error which is
twenty percent less than the standard error associated with the prediction
system based on the vehicle weight.
-------
-24-
The tire-dynamometer roll interaction is still an area of uncer-
tainity. More information about this interaction is desirable even
though the tire type correction terms are small in magnitude.
An equation to predict the power absorption setting for a single
large roll dynamometer is provided even though this type of dynamometer
is not commonly used in current certification or fuel economy testing.
This equation is structured in a manner similar to the equation for predicting
the power absorption of a small twin roll dynamometer because of the
prevalence of the small twin roll dynamometer in emissions and fuel
economy testing. The equation for the single large roll dynamometer
should provide significant guidance in the use of this type of dynamometer.
-------
References
1. G. D. Thompson, EPA Technical Support Report for Regulatory
Action, "Light Duty Vehicle Road Load Determination", December
1976.
2. C. S. Slaybaugh Ed., "Modern Tire Dealer", January 1976, Rubber/
Automotive Publications Inc., Akron, Ohio.
3. C. W. LaPoint, Suggestion during telephone conversation.
4. W. B. Crum, "Road and Dynamometer Tire Power Dissipation", Society
of Automotive Engineers, 750955.
5. Hoerner, Sighard, F., Aerodynamic Drag. The Otterbein Press,
Dayton, Ohio, 1951.
6. A. J. Scibor-Rylski, Road Vehicle Aerodynamics, John Wiley and
Sons, New York, New York, 1975.
7. B. Pershing, "Estimation of Vehicle Aerodynamic Drag", EPA-460/
3-76-025, October 1976.
8. Comments to the EPA Notice of Proposed Rulemaking - Fuel Economy
Regulations, September 1976.
9. W. D. Bowan, "Generalizations on the Aerodynamic Characteristics
of Sedan Type Automobile Bodies", SAE 660389, 400 Commonwealth
Drive, Warrendale, Pennsylvania, June 1966.
10. R.G.S. White, "A Method of Estimating Automobile Drag Coeffi-
cients", SAE, 400 Commonwealth Drive, Warrendale, Pennsylvania,
January 1969.
11. "Light Duty Truck Regulations", Federal Register, Vol. 41, No. 250,
December 28, 1976.
12. Analysis of the Comments to the EPA Notice of Proposed Rulemaking -
Federal Economy Regulations.
13. G. D. Thompson, "EPA Recommended Practice for Determination of
Vehicle Road Load", March 1976.
14. S. K. Clark, "Rolling Resistance Forces in Pneumatic Tires",
University of Michigan Report DOT-TSC-76-1, prepared for Department
of Transportation, Transportation Systems Center, Cambridge, Massa-
chusetts, January 1976.
-------
APPENDIX A
TEST FLEET IDENTIFICATION
-------
A-l
Table 1
Test Fleet
Vehicle
Identification
Number
101
201
301
401
502
601
804
901
1001
1102
1201
1301
1401
1501
1601
1702
1802
1901
2102
2203
2301
2401
2502
2602
2706
2802
2906
3011
3102
3212
3304
3402
3505
3613
3908
4014
4102
4202
4302
4402
4507
Model
Year
1974
1975
1975
1975
1975
1975
1974
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1973
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
Manufacturer
Chevrolet
Chevrolet
Pontiac
Pontiac
Ford
Oldsmobile
American Motors
Chevrolet
Chevrolet
Ford
Buick
Buick
Buick
Buick
Chevrolet
Ford
Ford
Buick
Mercury
Plymouth
Buick
Buick
Lincoln
Mercury
Toyota
Mercury
Toyota
Saab
Ford
Triumph
American Motors
Ford
Volkswagen
Honda
Mazda
Fiat
Mercury
Ford
Mercury
Ford
Datsun
Model
Name
Impala
Chevelle
Firebird
Ventura
Pinto
Cutlass
Gremlin
Body
Style
Sedan
Sedan
Sedan
Sedan
Sedan
Sedan
Sedan
Impala Stationwagon
Vega
Granada
Century
Special
Skylark
Apollo
Monza
Mustang Mach
Mustang
Sky hawk
Capri II
Valiant
LeSabre
Sedan
Sedan
Sedan
Sedan
Sedan
Sedan
Sedan
I Sedan
Sedan
Sedan
Sedan
Sedan
Sedan
Estate Stationwagon
Continental
Capri
Corolla
Comet
Celica
99
Mustang Mach
TR6
Pacer
Maverick
Rabbit
CVCC
Sedan
Sedan
Sedan
Sedan
Sedan
Sedan
I Sedan
Convertible
Sedan
Sedan
Sedan
Sedan
RX-3 Stationwagon
128
Mont ego
Gran Torino
Marquis
LTD
280Z
Sedan
Sedan
Sedan
Sedan
Sedan
Sedan
Test
Weight
(Ibs)
4560
4100
3640
3520
2800
4250
2970
5250
2680
3510.
4140
4020
3720
3910
3490
3000
3020
3200
2570
3600
4870
5590
5450
2350
2470
3320
2760
2710
3320
2650
3330
3320
2170
1900
2680
2180
4560
4570
4990
4860
3110
-------
A-2
Table 1 con't.
Vehicle
Identification Model
Number Year
Manufacturer
4607
4701
4801
4903
5001
5103
5203
5303
5403
5503
5603
5601
5701
5802
6002
6102
6202
6302
6402
6502
6702
6802
6909
8101
8401
9101
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1975
1976
1975
1975
1975
Da t sun
Pontiac
Oldsmobile
Dodge
Pontiac
Plymouth
Plymouth
Plymouth
Plymouth
Chrysler
Chrysler
Pontiac
Oldsmobile
Ford
Mercury
Ford
Ford
Ford
Ford
Ford
Ford
Ford
Volvo
Chevrolet
Oldsmobile
Chevrolet
Model
Name
Test
Body Weight
Style (Ibs)
B210 Sedan 2310
Lemans Sedan 4230
Cutlass Supre. Sedan 4330
Dart Sedan 3610
Lemans Sedan 4260
Valiant Custom Sedan 3580
Gran Fury Sedan 4840
Scamp Sedan 3680
Valiant Sedan 3620
New Yorker Sedan 5120
Newport Sedan 4840
Lemans (1) Sedan 4320
Delta 88 Sedan 4770
Granada Sedan 3760
Montego Sedan 4500
LTD Sedan 5020
Torino Sedan 4420
Granada (2) Sedan 3800
LTD Sedan 5060
Torino Stationwagon 5210
Gran Torino Stationwagon 5000
Gran Torino Sedan 4600
264DL Sedan 3290
Corvette Sedan 3850
Toronado Sedan 5170
Corvette (3) Sedan 3820
(1) Same vehicle as 5001.
(2) Same vehicle as 5802.
(3) Same vehicle as 8101, however head lamps up.
-------
A-3
TABLE ?
IDENTIFICATION OF VEHICLE
TY^FS
10
101
201
101
401
SO?
601
a.0^
901
1001
110?
1201
130]
1401
1S01
1601
170?
130?
1901
?10?
??0!
2101
2401
?50?
260?
2706
280?
2906
30 It
110?
121?
3104
140?
3505
3611
371?
3P01
390«
4014
410?
4?0?
410?
440?
TTPE OESC°!PTION
G 73-15
G 70-14
F 73-14
F 73-14
BR7«-13
Gw7fl-l5
6.45-14
L 73-15
A 73-13
037P.-14
G978-15
F973-15
FP7P-14
E 73-14
BP7S-13
la5/70Rl 1
190/7001 3
f?^7p-13
16SCR13
DP73-14
HR73-15
LR70-15
210SP15
1655P13
13?/70HC- 1 3
DR7R-14
18S/70HP1 4
165SR15
D^7n-13
1 8S«;P15
fe.Qe;-!^
QQ7S-14
1SSSP13
6.00S1?
1HS^P15
H 73-14
1SS9R13
l4S<;Rl 3
HP7A-14
WP7^-14
J07R-15
HP73-15
GOODRICH
UNIROYAL
i INT ROYAL
GENERAL
FIRESTONE
FIPESTONF
FIRESTONC"
GOODYEAR
GENERAL
FIRESTONE
UNIROYAL
FIRESTONE
UNIROYAL
I'NIPOYAL
GOODYEAR
FIRESTONE
FIRESTONE
"NTPOYAl.
GOODYEAR
r-OODYEAR
I'NIROYAL
FIRESTONE
MICHELIN
CONTINENTAL
TOYO
FIRESTONE
TOYO
SEMPERIT
MICHEL IN
MICHELIN
FIRESTONE
FIPESTONE
CONTINENTAL
PRIDGESTONF
MICHELIN
GOODYEAR
QRIDGESTOME
MicHEL IN
MNTPOYAL
"NIROYAL
^ICHFLIN
FIRESTONF
< noE*
2
?
?
?
1
1
?
?
?
]
1
1
1
?
]
1
1
1
1
1
1
1
1
1
1
1
1
1
1
]
?
1
1
?
1
?
1
1
1
1
1
1
-------
A-A
?(CONTINUED)
IDENTIFICATION OF VEHICLE TIRE TYPFS
10
4507
4607
4701
4801
4Q03
5001
5103
5?03
5303
5403
5501
5*01
5603
5701
5«0?
600?
610?
6?0?
630?
640?
650?
670?
6flO?
6909
8101
B401
9101
TIRE OF.SC£
l5CP14
GP73-15
J^7fl-15
GD7R-1S
OPTION
TOYO
RWIDGESTOMF
I'NIROYAL
GOODRICH
r-OOOYEAP
•IINIROYAL
GOODYEAR
r-OODYEAP
GOODYEAR
GOODYEAR
GOODYEAR
IJNTROYAL
GOODYEAP
UNTROYAL
FIPESTONF
r-OODYEAP
FIRESTOME
FIPFSTON'F
FIRESTONE
F IPFSTONF
r-OODYEAP
GENERAL
r-ENERAL
^'ICHEL IN
^OODYEAP
FIPESTONE
r-OODYEAt?
CO OF*
1
2
1
1
?
1
?
1
?
?
1
1
1
?
1
1
\
1
1
1
1
1
1
1
1
1
i
* 1 = Radial Ply Tires
2 = Bias or Bias-Belted Tires
-------
VEHICLE f
-------
B-l
TOTAL
TABLE
VEHICLE
1
«OAD LOAD
ID
101
201
50?
601
804
901
1001
1102
1301
1401
1501
1601
170?
1802
1901
210?
2203
2301
2401
2502
2602
2706
2802
3011
3102
3212
3304
3402
3505
3613
3908
4014
410?
420?
430?
440?
FO
(NT)
.2404E+03
0.3208E+03
0.1449E+03
0.2714E+03
0.2081E*03
0.3200E+03
0
0.2096E+03
0.1885E+03
0.1359E+03
0.1096E+P3
0.1549E*03
0.2275E+03
0.1920E+03
0.2947E + i>3
0.1??7E*t.'3
0.9967E+0?
0.177SE+03
0.1771E+03
0.2152E*03
0.1704E+03
0.1747E+03
0.1441E+03
0.1847F*H3
0.15S3E*n3
Fl
(KG/SEC)
0.4126E*01
•0.7530E*01
0.1164E*0?
•0.2887E*01
•0.3156E*01
•0.9857E*01
0.1706E*02
0.6818E*01
0.4893E*01
0.1204E*02
0.1847E*03
0.?040E*03
0.1368E*03
0.1826E*n3
, 1443E + 02
,9384E*01
,1268E*01
,5324E*01
,4903E*01
-0.2344E*01
0.1807E*01
0.800SE+01
0.8139E*01
0.4943E*01
0.491dE*01
0.6409E*01
0.4672E+01
0.4749E*01
0.5071E*01
0.6461E*01
0.6f45E*01
0.1556E+02
•0.3787E*00
0.1006E*u?
0.5347E*00
• 0.2685E*01
0.b598E*03 -n.3749£*02
0.5826E*liO
F2 '
(KO/M)
0.9936E*00
0.20uOEtOO
0.94S7E*00
0.65b2E*00
0.4068E*00
0.4falOt*00
0.393bE«00
0.22S5E*00
0.359fcE*00
0.5647E*00
0.7477E*00
0.6bl5E*00
0.5077E*00
0.3499E*00
U.460?E*00
0.3735E+00
0.7864E*00
0.3760E*00
0.5202f.*00
0.6Hb"9t*00
0.
0.667oE*00
(NT)
0.b253E*03
0.64b8E*03
0.b050E*03
0.5528E*03
0.4970E*03
O.S430E*03
O.t-.898t*03
0.b011E*03
O.S880E*03
0,bd87E*03
0.b460E*03
0.5741E*03
0.423lt*03
O.S188E+D3
0.630hF*i)3
0.7043£*03
0.6588F*03
0.4007E*03
0.5014E*03
n.S110E*03
0.3955E*03
0.4«J71E*03
0 . '( 0 3 1 E * 0 3
(HP)
18.74^
19.44^
15.13''
16.569
17.147
20.673
15.020
17.6??
19.3M
16.364
17.207
14|?1 1
15.55!)
12.807
15.551
i9.74u
12.011
11.923
13.44-*
15.02-
12.734
15.11^
16.11^
1U871
13.1?':
19. 3.v,
21. 0 7 '-
19.49.,
-------
B-2
TABLE 1 (CONTINUED)
TOTAL VEHICLE HOAD LOAO
10
4507
4607
4701
4801
4903
5001
5103
5203
5303
5403
5503
5601
5603
5701
590?
6002
6102
6202
6302
6«»02
6502
6702
6802
6909
8101
8401
9101
FO
(NT)
0.1219E+03
0.1275E*03
0.2164E+03
0.21B6E*03
0.1376E*03
0.3866E+03
0.1549E+03
0.24<*8E*03
0.1736E+P3
0.2835E+03
0.3347E+03
0.1974E*03
0.1448E*C'3
0.2278E*03
0.1740E+03
0.2486E*03
0.1494E*03
0.1580E+03
0.2211E*C3
0.1487E*03
0.2053E*03
0.2097E*03
0.29(S5E*03
0.1059E*03
0.349?E*03
0.24H7E*03
0.2331E*03
Fl
(KG/SEC)
0.9159E+01
0.393bE*01
0.2275E+00
-0.5525E+00
0.1354E*02
-0.1570E*02
0.1490E*02
0.6799E*01
0.1283E+02
-0.3427E*01
-0.3877E*01
0.7108E*01
0.1667E»02
0.7702E+01
0.7805E*01
0.1023E*02
0.1807E*02
0.1733E*02
-0.1301E+01
0.1430E*02
n.8997E*01
0.5246E*01
-0.7523E*01
0.1201E*02
-0.9181E*01
0.6112E*01
0.4870E*Ul
F2
(Kb/M)
0.2515E*00
0.3339E*00
0.6013E*00
0.72?4E*00
U.1701E*00
0.1039E*01
0.2431E*00
0.4845E*00
0.2600E*00
0.7847E+00
0.812RE*00
0.4269E*00
0.2314E*00
0.47bOE*00
0.4446E+00
0.37d3E+00
0.2066E*00
0.2446E*00
0.71b2fc*00
0.35836*00
0.5551E*00
0.73856>00
0.9875E*00
0.3338E*00
0.7654E+00
0.5472E*00
0.4822E*00
F-«>50
(NT)
n.4S22E*03
0.3833E*03
0.5219E*03
O.S696E*03
O.S253E*03
O.S546E*03
0.f093E*03
0.6JH8E*03
0.b902E*03
0.5989E*03
0.6541E*03
0.5695E*03
0.^329E*03
0.6372E*03
0.b706E*03
0.6661E+03
0.^574E>03
0.6676E*03
0.^528E*03
0.o473E*03
0..6837E + 03
0.^958E*03
0.6216E*03
0.b411E*03
0.b263E*03
0.
16.623
18.26^
19.14^
17.689
17.94^
19.60^*
17.06^
lb.9h^
19.097
17.101
19.96.3
19.70.3
20.00 '-
16.56-*
19.401
20-. 4^2
20.8'?^
18.631
16.21-
15.77^
19.741
17.46"
-------
B-3
TA6LF 2
TWIN SMALL ROLL DYNAMOMETER ESTIMATES
FOR VEHICLES WITH BIAS-BELTED TIKES
ID
101
201
301
401
502
601
804
901
1001
1102
1?01
1301
1401
1501
1601
1702
1*02
1901
2102
2203
2301
2401
2b02
2602
2706
2R02
2906
3011
3102
321?
3304
3402
3505
3613
3908
4014
4102
43
0.^7H9E*u2
-0.2253E*«..?
0.5?2lE4ii3
0.9?91E*02
Fl
(KG/SEC)
0.1685E*01
-0.1011E+02
0.9058E+01
-0.4815E*01
-0.5158E*01
-0.1194E*0?
0.1492E+02
0.4743E*01
0.2733E*01
0.5472E*01
0.1311E*02
0.9118E*01
0.1204E*02
0.7143E*01
-0.3595E*01
0.3253E*01
0.3557E*01
-0.3998E*01
-0.4870E*00
-0.6571E*01
0.6549E*01
0.4722E*01
0.3391E*01
0.3134E*01
0.5096E*01
0.1186E*01
-0.6826E+01
-0.b081E*01
0.5142E*01
-O.H02E*02
0.4198E*01
0.1398E*02
-0.1008E*01
0.8392E*01
-0.1?33E*01
-0.3536E*01
0.6804E*01
0.1840E*02
-0.3959E*02
-0.1397E*01
. . F2 '".'
(K(3/M,)
0.5860E*00
0.9936E*00
0.20UOE*00
0.6926E*00
0.7195E*00
0.9457E*00
0.10J2E*00
0.6562E*00
0.4068E*00
0.4610E*00
0.3270E*00
0.3936F+00
0.22b5E*On
0.3596E*00
0.49b3t*00
0.4373E*00
0.4544E+00
0.5b<*7E*00
0.51b8t*00
0.747?E*00
0.5202E*00
0.6615E+00
0.5l)77F.*00
0.3366E*-00
0.3499E*00
0.4602E*00
0.6477F. + 00
0.69^3£*00
0.3735E*00
0.78b4F.*00
0.3760f*00
0.1693E+00
0.520?F.*00
0.2122E*00
0.6015E*00
0.6tJ59E*00
0.4B74E*00
0.1744E*00
0.1bb«F.*01
0.6b7oe *00
FP50
(NT)
0.4319E*03
0.4741E*03
0.3229E*03
0.3680E*n3
0.3513E*03
0.4033E*03
0.3772E*03
0.^904E*03
:0.3491E*03
0.3982E*03
0.4445E*03
0.4Q99E*03
0.3835E*03
0.3668E*03
0.2601E*03
0.^239E*03
0.3643E*03
0.2932E*03
0.3141E+03
0.3886E*03
0.4301E*03
0.4963E*03
0.b442E*03
0.3005E*03
0.29ttlE*03
0.3353E*03
0.2830E*03
0.3762F*03
0.341fiE*03
0.?910E*03
0.3275E*03
0.3677E*03
0.3484E*03
0.3117F. + 03
0.3500E*03
0.3695E*03
0.4834E*03
0.4759E*03
0.4654E*03
0.3949t »03
HPH50
(HP)
12.945
14.211
9.677
11.030
10.52H
12*OP8
11.305
14.69h
10.46h
11.935
13.323
12.2*o
11.491
10.99=?
7.797
9.7P.7
10.9] *
8.78*
9.41a
11.64S
12.890
14.874
16.311
9.00H
8.933
10.050
8.481
11.334
10.244
8.720
9.817
11.021
10.441
9.341
10.489
11.075
14.469
14.?63
13.950
11.81S
-------
B-4
TABLE 2 (CONTINUED)
TWIN
FOR
ID
4507
4607
4701
4801
4903
5001
5103
5203
5303
5403
5503
5601
5603
5701
5802
6002
6102
6202
6302
6402
6S02
6702
6802
6909
8101
8401
9101
0.
0.
0.
0.
0.
0.
0.
0.
o.
0.
0.
0.
-0.
0.
o.
0.
-0.
-0.
o.
-0.
0.
0 •
0.
0.
0.
0.
0.
FO
(NT)
7320E
4625E
+ 01
+ 02
1086E+03
7880E
1699E
2949E
6807E
9862E
7524E
1803E
2383E
10S7E
3265E
6606E
4664E
7 Q "1 4*.£r
j *f . 5 OC.
1149E
+ 02
+ 02
+ 03
+ 02
+ 02
+ 02
+ 03
+ 03
+ 13
+ 01
+ 02
+ 02
*02
*02
2716E+01
9574E
33R9E
*02
*02
1105E+02
6 1 9 1 E
1905E
1P85E
210PE
2126E
9405E
*02
*03
*02
+ 03
+ 02
*OH
SMALL ROLL DYNAMOMETER ESTIMATES
VEHICLES WITH BIAS-BELTED TIRES
Fl
(KG/SEC)
0.7829E+01
0.2488E+01
-0.1966E+01
-0.2395E+01
0.1114E+02
-0. 1894E+02
0.1113E+02
0.3697E+01
0.1011E+02
-0.5978E+01
•0.9662E+01
0.3870E+01
0.1374E+02
0.5913E+01
0.5897E+01
0.9278E+01
0.1626E*02
0.1308E+02
-0.3209E+01
0.1254E+02
0.7061E+01
0.2287E+01
-0.1098E+02
0.9953E+01
-0.1079E+02
O.S518E+01
0.3261E»01
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
o.
0.
0.
0.
0.
0.
o.
0,
0.
t-2
(KO/M)
2515E+00
3359E
6013E
7274E
1701E
1039E
2431E
46**5E
2600E
7847E
8128E
4269E
2314E
475QE
4446E
3783E
20«6E
2446E
7182E
3583F
55blE
73S5E
9875F.
3338E
765^E
+ 00
+ 00
+ 00
+ 00
+ 01
+ 00
+ 00
+ 00
+ 00
+ 00
+ 00
+ 00
+ 00
+ 00
+ 00
+ 00
+ 00
+ 00
+ 00
+ 00
+ 00
+ 00
+ 00
+ 00
5472E+00
48f;2E
+ 00
0
0
0
0
0
0
0
o
0
0
0
0
0
o
0
o
o
0
0
n
0
0
o
0
0
0
0
(NT)
.3079E
.2697E
•3650E
.3886E
•3508E
+ 03
+ 03
+ 03
+ 03
+ 03
.3906E+03
.4382E
.<*233E
+ 03
+ 03
.4310E+03
•43d7E+03
• *»283E
.4054E
.^1956
• <*355E
• <*005E
.^757E
.HI362E
• **11RE
•3828t
.^254h
.446 IE
• <+8l9E
• <*385E
•4020E
•3513E
•4179E
.4078E
+ 03
*03
+ 03
+ 03
+ 03
+ 03
+ 03
+ 03
+ 03
+ 03
+ 03
*03
+ 03
+ 03
+ 03
+ 03
+ 03
HP<«50
(HP)
9.22^
8.082
10.940
11.647
10.515
11.707
13.133
12.686
12.91*
13.14*
12.83r
12.151
12.57a
13. OS-^
12.0(U
14. 25/
13.67<*
12.342
11.472
12.74V
13.372
14.44-4.
13.142
12.050
10.530
12.526
12. 2?^
-------
B-5
TWIN SMALL
TAriLt 3
WOLL DYNAMOMtTEP. PO*tR flclSORPTION ESTIMATES
FO* VEHICLES WITH MDIAL TTRhS
ID
101
201
301
401
502
601
804
901
1001
1102
1201
1301
1401
1501
1601
1702
1802
1901
2102
2203
2 301
2401
2502
2602
2706
2402
2906
3011
3102
3212
3304
3402
3505
3613
3908
4014
4102
4202
4302
4402
FO
(NT)
0.5961E*02
•0.2327E*02
0.8863E*02
O.H5S3E*02
0.1756E*03
0.1724E*02
0.3281E*02
.0.4175E*C2
•0.12576*02
•0.19846*02
•0.1846E*n?
0.7333E*02
0.1301E*P2
0..?457E*<;2
0.15176*03
•0.7248E*'.'!
0.
0.537bE*02
0.1473E*"2
0.*»325E*01
•0..->651E*U2
0.3142E*01
O.M41E*02
O.S200E*02
Fl
(KG/SEC)
0.1414E*01
0.1040E*02
0.8876E*01
0.4969E*01
0.5252E*01
0.12076*02
0.1464E*02
0.4515E*01
0.2625E*01
n.5216£*0l
().1316E*02
0.8975E*01
U.7160E*01
n.3076E*l)l
0.3445E*ul
•0.4224E*01
•fi.6730E*00
>.6477E*01
i.4406E*01
3310E*01
3099E*01
().4767E*01
0.1062E*01
•0.6169E*01
«.50616*01
•0.1108E*02
0.3905E*01
0.1382E*02
o!a338E*Ol
•0.12876*01
•0.3597E*l'l
0.68346*01
0.1814E*02
•0.39746*02
•0.1486E*01
1-2
U.99J6E*00
0.20«iQ6*00
0.94b7t>00
0.103?E*00
0.65o2E*00
0.40b8E*U.O
0.46lOE*00
0.32/OE+OO
0.3936E*UO
0.22b5E*00
.0.49b3E*00
0.4373E*00
O.Slt$8E*00
0.6615F*00
0.50776*00
0.3J66E*00
0.4bU2E*00
0.64/7E*00
0.3/J5E*00
0.376()E*00
0.6()iSt*00
F.u50
(NT)
0.3839E*03
0.42536*03
0./>7bOE + 03
0.12356*03
0.32766*03
03
0.3797E*03
0.-1626*03
0.3846E*n3
0.35746*03
0.
0.^4596-
0.2356E*«)3
'0.3002E*o3
0.3385E*03
0.26686*03
'0.39746*03
0.^2396*03
. *03
0.^814E*03
0. *
0. )577E*03
0.4482F*03
0.4352E*03
0.'*329E*03
0.^592^*03
HPlo/Su
(HP)
11.50/
12.74(;
8.243
9.697
9.817
11.340
9.93.3
13.365
9.280
11.379
12.475
11.52*
10.711
9.627
7.062
10.147
7.99T,
8.751
11.20*
11.910
13.83-1
9.361
7.9PM
11.03*
9.4?^
8.231
10.10'..
10.24 *
8.85V
lo!7?f.
13.433
1.3.04.-,
-------
B-6
TAdLK 3 (CONTINUED)
T*IN SMALL ROLL DYNAMOMETER POwrlW ABSORPTION USTIMATES
VEHICLES WITH KAOIAL TTWr.S
ID
4507
4607
4701
4801
4903
5001
5103
5203
5303
5403
5503
5601
5603
5701
5802
600?
610?
620?
630?
640?
650?
670?
6«0?
6909
8401
9101
FO
(NT)
•0.1193E*02
0.2209E*02
0.8817E*02
0.5423E*C2
•0.?.160E*02
0.2728E*03
0.<*?12E*02
0.7191E*02
0.14?6E*03
0.2105E*03
0.2062E+02
-0
Fl
KG/SEC)
7797E*01
2361E*01
2535E*01
1088E*02
1913E*02
(
0.
0.
•0.
0.
•0.
o.
u.
•0
0.1350E*02
0.5547E*01
0.5750E*01
0.33^9^*00
0.6013E*00
0.7274E*00
0.17J1E*00
3683E*01
9681E*01
6241E*01
0.?.bOOF«-00
0.2J14E*00
U.1294E*02 0.2«*<:*6t*00
-0.3356E*01 0.71ri2E*00
,1239E*02 0
,6926E*01 0
0.4439E*02 0.2241E*01
0.1688E*03 -0.1
0.987^^*00
0.7?18E*02
-0.1099E*02
0.5436E*01
0.3061E*01
0.5472t>00
(NT)
0.''l609t*C3
Mi 3
*C3
0.3951£*n3
03
0.3994F
0.3962E
0.
.). M74E-
0.
0.
jri71F.*C3
0.3250E*03
0.3921E*03
o.3815E»03
(HP)
8.631
7.271
10.1H4
10.817
10.91S
11.^7?
11.7S?
11.841
11.3^
11.4b^+
13.37S
12.Md
11.60 1
12.367
12.377
11.49'.
9.741
11.7^3
11.433
-------
B-7
TABt_F
SINGLE LARGE
ABSORPTION ESTIMATES
10
101
201
301
401
502
601
80<+
901
1001
1102
1201
1301
1401
1S01
1601
1702
1802
1901
2102
2203
2301
2401
2502
2602
2706
2802
?906
3011
3102
3212
3304
3402
350S
3613
3908
4014
410^
4202
4302
4402
FO
(NT)
0.1387E+03
0.2484E+G3
O.e>252c + 02
0.1690E+03
0.141PE+03
0.2216t+»3
0.1907E+02
O.HR*1E+02
0.1084E+03
0.6P53E+02
0.1460E+02
O.S499E+ri2
().-*093E + (''2
0.65<*2E + 02
0.1361E+03
O.S865E+02
0.-J140E + 02
0.1360E+03
0.44Q6E+02
0.1607E+03
0.6382E+02
0.*628E+02
0.2510E*03
0.t>032E + 02
0.4980E+02
0.1354E+03
0.) 191E+03
0. 16*2E+03
0. 7703E+02
0. 1578E+03
0. 7237E+02
0.1923E+02
0.1 1S7E+03
0. 1092E+H2
0.'->622E + 02
0.1226E+U3
0. 1052E+03
0.3601E + C,?
U. -S825E + (/3
0. 1644E+^3
Fl
(KG/SEC)
0.1781E+01
-O.KU3E + 02
0.9245E+01
-0.4689E+01
-0.4911E+01
-0.1203E+0?
0.1^9bE+02
0.4310E+01
0.2750E+01
0.5832E+01
0.1359E+02
0.9040E+01
0.1190E+02
0.7702E+01
-0.3345E+01
0.3426E+01
0.3728E+01
-0.3911E+01
-0.2950E+00
-0.5076E+01
0.6487E+01
0.5042E+01
0.3091E+01
0.3141E+01
0.4927E+01
0.1282E+01
-0.6635E+01
-0.6041E+G1
0.5343E+01
-0.1089E+02
0.4193E+01
0.1394E+02
-0.1010E+01
0.8363E+01
-0.1072E+01
-0.3608E+01
0.6173E+01
0.1864E+02
-0.3968E+02
-U.1534E+01
F'2
(M.i/M)
0.5eb(>E + 00
0.9936E+00
0.2000E+00
0.6926E+00
0.7195E+00
0.94b7E+00
0.1032E+00
0.6562E+00
0.40t>8E + 00
0.4610E+00
0.3270E+00
0.3936E+00
0.22b5E+00
0.3596E+00
0.49b3E+00
0.4373K+00
0.4544t+00
0.56H7E+00
O.S188E+00
0.7477E+00
0.52C2E+00
0.66i5t' + 00
0.5077E+00
0.3366t+00
0.3499F+00
0.4602E+00
0.64/7E+00
0.69<*3E + 00
0.3735E+00
0.786<4t_ + 00
0.3/60E+00
0.16^3E+00
0.5202E+00
0.2122t+00
0.60 15E+00
0.68S9E+00
0.4874E+00
0.17^4E+00
0.1658E+01
0.6670E+00
Ff-flSO
(NT)
0.^712E+03
O.S184E+03
O.J691E+03
0.4102E+03
0.3915E+03
0.^254E+03
0.4Q47E+03
O.S127E+03
0.3731E+03
0.4292E+03
0.4818E+03
0.<*536E + 03
0.4196E+03
0.^172E+03
0.3087E+03
0.3537E+03
0.3917E+03
0.3306E+03
0. J466E+03
0.4207E+03
0.4687E+03
O.S294E+C3
0. S736F. + 03
0.^987E + ()3
0.334SE+03
0. ^939E + 03
0.^944F. + 03
O..^fl00t + 03
0..'<830E + 03
0.3071E+03
0. J544E + 03
0.^1b4E+03
0.3530E+03
0.3033t+03
0.3727E+03
0...1846E + 03
0.4866E+03
0.'S405E + 03
0.lj23Ht + 03
0.463 3t +03
HPi«i5(i
(H»)
14.123
15.539
11.061
12. 29^
11.731
12.749
12.1?>i
15.367
11.16.H
12. 86^
14.439
13.S97
12.57h
12.50^
9.253
10.60')
11.740
9 . 9 K)
10.3*9
12.611
14.04^
IS. 867
17.193
8.9SJ
10.02^
11.807
8.82<^
11.390
11.4PO
9.21'
10.6?^
12.4S1
I0.5«i,'
9.1(^
11.171
11.SP7
1**.5^-.
16.?0]
15.700
13.8^0
-------
B-8
TABLE 4 (CONTINUED)
SINGLE LARGE *OLL UYNAMOMETE* POWER ABSORPTION ESTIMATES
ID
4507
4607
4701
4801
4903
5001
5103
5203
5303
5403
5503
5701
5802
6002
6102
6202
6302
6402
6502
6702
6802
6909
8101
8401
9101
FO
(NT)
0.2457E*02
0.1 112E+03
0.3266E+03
0.16P9E+03
0.1137E+03
0.2030E+03
0.1374E*03
0.4170E*0?
O.U?OE*03
0.1270E+H3
0.3573E*0?
0.1400E*(>3
0.14?8E+0?
0.6898E*'!?
0.1012E*03
0.2276E+03
0.3735E+02
0.2415E+03
0.50P2E+0?
0.1?54E*03
Fl
(KG/SEC)
0.7695E*01
0.2394E*01
•0.1743E*01
•U.2356E*01
0.1126E+0?
0.1?10E*02
0.3594E»01
0.9719E*01
0.5799E*()1
0.9280E*01
0.3860E*01
0.1410E*02
0.6042E*01
0.6171E*01
0.1626E*02
0.1297E*02
•0.2935E*01
0.1276E+02
0.7041E*01
•0.1104E+02
0
•0
0.5897E*01
0.3185E*01
.1021E*02
.1087E*02
0.2515E*00
0.3359E*00
0.7274E*00
0.17U1E*00
0.10J9E«01
0.26uOE*00
0.23l4E*00
0.47bOE*00
0.35»3E*00
0.5551E+00
0.73H5F+00
0.33J8E*00
0.547?E*00
0.4H22E*00
(NT)
0.3222E+03
0.28':>6fc*03
0.3877E*03
0.4220E*03
0.48S2E*03
0.**6S4t*03
').H369E*03
0.4509F*03
0.5168E*03
0.5034F*03
0.4839E+03
O.S036E*03
0.3810E*'J3
0.4554E*03
(HP)
9.65^
8.55*
11.6P1
12.647
11.74^
13,
13,
14,
13,
14,
*12
94n
09»-.
I5h
14.517
lb!<»9,'i
15.O*/
14.503
12.981
14.337
15.67,1
14.21?
12.95*
13.641
13.112
-------
APPENDIX C
EFFECTS OF VEHICLE TYPE
AND VEHICLE PROTUBERANCES
-------
C-l
Table 1
Fastback Vehicle Selection
Vehicle
Identification
Number
301
502
1601
1702
1901
2102
2602
2706
2906
3102
4507
4607
Description
Inclined Rear
Surface Angle
(Degrees)
Pontiac
Ford
Chevrolet
Ford
Buick
Mercury
Mercury
Toyota
Toyota
Ford
Da t sun
Da t sun
Firebird
Pinto
Monza
Mustang Mach I
Skyhawk
Capri II
Capri
Corolla
Celica
Mustang Mach I
280Z 2+2
B210
20
27
19
20*
19
26
30
21
16
20*
22
16
Inclined Rear
Surface Area
(Percentage of
Reference Area)
37
37
36
37
27
36
30
Vehicles Meeting Fastback Criteria
Vehicle
Identification
Number
301
1601
1702
1901
2906
3102
4607
Description
Pontiac
Chevrolet
Ford
Buick
Toyota
Ford
Datsun
Firebird
Monza
Mustang Mach I
Skyhawk
Celica
Mustang Mach I
B210
* Data supplied by Ford Motor Company
+ Area measurements were made on only those vehicles with an
inclined rear surface angle of 20 degrees or less.
-------
C-2
TARLP 2
CALCULATED VEHICLE DRAG
CofcFTIClFNTS
ID
101
2*1
301
401
50?
601
804
901
1001
1102
1201
1301
1401
1501
1601
170?
18^2
1901
2lo?
2203
2301
240]
250?
260?
2706
2802
29A6
3011
310?
3212
3304
340?
35f>5
3613
3903
4014
410?
42"?
43n?
44n?
V&LUE*
2
2
1
2
2
2
2
2
2
2
2
2
2
2
1
I
2
1
2
2
2
2
2
2
2
2
1
2
1
2
2
2
2
2
?
?
2
2
2
2
C D
0.5889
0.6776
0.4932
0.5^.84
0.6269
0.6027
0.6461
0.6784
0.6?4<>
0.6237
0.6631
0.6128
0.605R
0.5445
0.4677
0.5715
0.644^
0.5?96
0.5735
0.6425
0.6096
0.7024
0.7509
0.5689
0.5703
0.5367
0.5589
0.6614
0.5985
0.5^70
0.4963
0.579?
0.6346
0.6464
0.6798
0.7631
0.7110
0.6676
O.MM
0.5134
-------
C-3
2
-------
C-4
Table 3
Estimated Protuberance Effects
Vehicle
Identification
Number
804
901
2401
6702
1974
1975
1975
1975
Manufacturer
Am. Motors Gremlin
Chevrolet Impala
Buick Estate
Ford Gran Torino
Estimated
Body Protuberance
Style Power
Sedan 0.4
Stationwagon 0.4
Stationvagon 0.4
Stationwagon 1.0
Vehicle 6702 was equipped with a roof rack and air deflector. The
other vehicles in the table were equipped with a roof rack only. The
remaining vehicles in the test fleet were not equipped with roof racks.
-------
C-5
TABLE 4
PREDICTED DYNAMOMETER POWER ABSORPTION
ID
101
201
301
401
502
601
804
901
1001
110?
1201
1301
1401
1501
1601
1702
1802
1901
2102
??03
2301
2401
2502
2602
2706
2902
2906
3011
310?
3212
3304
3402
3505
3613
3908
4014
4102
4202
4302
4402
AREA
(TT)
24.20
23.30
20.70
21.90
19.40
23.30
19.04
24.40
IS. 40
22.60
23.30
23.30
21.90
21.90
18.70
19. SO
19.50
1». 70
18.90
21.^9
24.20
2^.40
25.90
19.00
18.40
21. fO
17.70
20.67
19.50
18.30
21.05
21.60
20.00
16.97
1*.19
17.40
23.40
24.20
26.00
25.00
TYPE *
2.00
2.00
1.00
2.00
2.00
?.oo
3.00
3.00
2.00
2.00
2.00
2.00
2.00
2.00
I. 00
1.00
2.00
1.00
?.oo
2.00
2.00
3.00
2.00
2.00
2.00
2.00
1.00
2.00
1.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
HP«50
(HP)
11.507
12.746
8.243
9.697
9.817
11.340
9.933
13.365
9.2BO
11.379
12.475
11.528
10.711
9.627
7.062
8.998
10.147
7.996
8.751
11.202
11.910
13.838
15.702
8.726
8.472
9.361
7.988
11.039
9.424
8.231
8.435
10.100
10.249
8.857
9.984
10.720
13.433
13.045
12.975
10.766
PP«50
(HP)
12.061
11.612
8.933
10.915
9.669
11.612
9.889
12.560
9.170
11.263
11.612
11.612
10.915
10.915
8.070
8.415
9.718
«. 070
9.419
10.7*0
12.061
12.560
12.908
9.469
9.170
10.765
7.638
10.302
8.415
9.1PO
10.491
10.7*5
9.968
8.458
9.066
8.672
11.662
12.061
12.9S8
12.459
-------
C-6
TABLE: 4 (CONTINUED)
PREDICTED DYNAMOMETER POWER ABSORPTION
ID
4507
4607
4701
4801
4903
5001
5103
5203
5303
5403
5503
5601
5603
5701
580?
6002
610?
620?
6302
6402
6502
670?
680?
6909
8101
8401
9101
AREA
(FT)
17.64
17. ?2
23.30
23.30
21.50
23.30
21.59
24.38
21.37
21.59
24.30
23.30
24.52
24,?0
2?. 60
23.40
25.00
23. QO
22.60
25.00
25.60
25.60
24.20
22.07
17.20
23.90
17.20
TYPE*
2.00
I. 00
2.00
2.00
2.00
2.00
?.oo
2.00
2.00
2.00
?.oo
2.00
2.00
2.00
2.00
?.oo
2.00
2. OP
2.00
2.00
?.oo
3.00
?.oo
2.00
2.00
2.00
2.00
HPP50
(HP)
8.631
7.273
10.184
10.817
9.185
10.915
11.972
11.876
11.762
11.841
11.822
11.359
11.610
11.454
11.126
13.375
12.612
11.168
10.594
11.603
12.367
13.888
12.377
11.496
9.741
11.753
11.433
PPW50
(HP)
8.7G1
7.431
11.612
11.612
10.715
11.612
10.760
12.151
10.650
10.760
12.111
11.612
12.220
12.061
11.263
11.662
12.459
11.911
11.263
12.459
12.759
13.759
12. OM
10.999
8.572
11.911
8.572
Type = 1 Designates a Fastback Vehicle
Type = 2 Designates a Non-Fastback Vehicle
Type = 3 Designates a Non-Fastback Vehicle
Equipped with a Roof Rack
------- |