Homework #2
ME 364 – Fall ‘10
8/30/10
Due: Friday, 9/3/10
Show all of your work on the following problems using appropriate unit conversions and
significant digits rules:
Use the data for your assigned vehicle (see table below for assignment, see ME 364 website
under Vehicle Data for data sheets) for the following problems:
1. Assuming no aerodynamic drag or friction losses in the drivetrain, estimate the maximum
speed of your vehicle in each of the forward gears: 1st, 2nd, … high gear. Give answers in
units of ft/s and mph.

Use the engine RPM at the maximum power for your calculations along with published
gear ratio and differential data.

Use the tire size calculator at http://www.miata.net/garage/tirecalcold.html or
http://www.paspeedo.com/calculator.htm to get the diameter of your tires depending on
the size, i.e., a P205/55R16 tire has a diameter of 24.9 inches.
2. Determine the mass factors, km, for all forward gear ratios on your vehicle. See next page of
this homework for an enlarged version of the Bosch mass factor plot and a curve-fit equation
that you can use. Round mass factors to 3 significant digits.
3. Determine the coefficients Am and Bm for a 2nd order curve fit to the engine output for your
vehicle.
4. Determine the coefficients C1, C2 and C3 for a 3rd order curve fit to the engine output for your
vehicle.
5. Plot the curve-fit engine power data for your vehicle using both the 2nd-order and 3rd-order
models. Plot all four lines on a single plot. Start the plot at 500 RPM and end it at the RPM
associated with the maximum power.
6. Plot the curve-fit engine torque data f for your vehicle using both the 2nd-order and 3rd-order
models. Plot all four lines on a single plot. Start the plot at 500 RPM and end it at the RPM
associated with the maximum power.
Last Name
Starts With:
Vehicle #1
Last Name
Starts With:
Vehicle #2
A to B
’05 Volkswagen Jetta
R
'06 Pontiac Solstice
C to D
’05 Ferrari 612
S
'06 Mazda MX5 Miata
E to J
’05 Mercedes SLR McLaren
T
'08 Dodge Challenger SRT8
K to M
’06 BMW 330i
W to Z
'08 Pontiac G8GT
Determining Rotational Inertia
Coefficient, km
Z
X
m
vH
kg 

units
of


liter


0.3 N t N f 
1 
units
of


r
meter


Curve-fit Equation for Mass
Factor
0 .3 N t N f 
1 
X
 units of

r
meter 

Z
m
kg 
 units of

vH 
liter 
k m  2.73E-02  X  9.85 E-04  X 2
-5.71E-05  Z  8.22 E-08  Z 2
-2.87 E-05  X  Z