Super Mileage Car

Final Project Report

Messiah College

Head Project Engineer David Gruber April 29,1994

Pictured here is the head project engineer

David Gruber with the SPUD 500 SPUD is an acronym for Super Petroleum Utilizing

Device 500 represents the mileage the design is striving

for

Preface: The super mileage car is the compilation of one year of research, experimentation, and

trial and error. This project could never have been possible without the generous contributions made by the following people:

Tim Shaffer- Calabrese and Sons Machine Shop, Mechanicsburg, PA

David Zumbro- Garron Plastics of PA., Hamsburg, PA

Mike Butala- Hamsburg Area Community College, Hamsburg, PA

Ronald Reinfield- H.E.K. Racing, Dillsburg, PA

Robert Urich- Bob's Outdoor Power Center, Lewisberry, PA

As well as the construction and testing help of:

Walter DeWall

John Meyer

And especially my parents Thomas and Linda Gruber for their help and support. Thank you all very much.

Dave

Table of Contents

Topic

Abstract Aerodynamic Design Wind Tunnel Testing Frame Design Steering Engine Mounts Jack Shaft Mounts Seats Exterior Frame Exterior Coverings Engine Design Condenser Replacement Muffler modification Gasoline Vaporization History Vaporization Operation Braking Speed Monitoring Devices Safety Devices Testing Conclusions Suggestions Cost Summary Vendors Listings Bibliography Gantt Chart Appendix A Appendix B Appendix C Appendix D

Abstract: The super mileage car was a two part design project. The first aspect of the project

was aerodynamic efficiency, while the second aspect of concern was engine efficiency.

Three aerodynamic models were designed and tested in a sub-sonic wind tunnel. The

results of the tests determined which body was the most efficient at fighting drag and skin

friction. An internal frame was then designed to fit inside the winning shell design. This frame

offered the support the car needed to function. Weight was kept at a minimum to increase in the

efficiency of the design.

As previously mentioned the second aspect of the project was engine efficiency. An

eight horsepower Briggs and Stratton engine was chosen due to its large displacement versus

small fuel consumption. The engine was then modified to further increase its fuel efficiency. A

gasoline vaporizer was designed and built which allows the fuel to bum at a much leaner ratio

without loss of power. Also, the points were replaced with an electronic impulse ignition. This

too will lead to an increase in fuel economy.

Through the conjunction of these two aspects, a one-seated, super mileage car was

constructed. This car averages a minimum of 25 miles per hour, while getting a minimum of 450

miles per gallon of gasoline. The car was tested extensively to assure complete optimization.

Aerodynamic Design: After extensive research into aerodynamic design three aerodynamic designs were

created. Two of the designs were developed to minimize aerodynamic drag through their

streamlining. Large drag raisers were minimized thus increasing the smoothness of the air flow

over the body. Skin friction was kept at a minimum by designing bodies that allow minimal room

inside while still reducing the drag raisers. The third design was to act as a control group by

simulating a conventional modem day sports car. The shell had to be designed around the driver,

the engine, and the wheels. This was accomplished by measuring the minimum spatial

requirements of each individual component and then putting all these parts together into the shell.

Design #1 This design was based on the nearly optimal shape for a low drag strut found in Fluid

Mechanics by Riley and Zachery. The model consist of this exterior shape rolled 180 degrees into

the third dimension. A one-half inch lip was added to the bottom to increase the interior room.

(Appendix A, Fig. 1-4)

Design #2 This design was based on the winning University of Michigan SunRayce 1993 entry.

This design was discovered in the September 1993 issue of Popular Mechanics. The design was

modified slightly to eliminate some of the extra surface needed for the mounting of solar panels.

(Appendix A, Fig. 5-8)

Design ^3

Design three was modeled after the Ford Probe. This is a sleek sports car that claims

excellent aerodynamic design. This design acted as the control, group so that the other two

designs could be compared to something. (Appendix A, Fig. 9-12)

The three designs were drawn with AutoCad Release 10. These files were converted to

dxf.out files and taken to Calabrese and Sons Machine Shop in Mechanicsburg, PA. The files

were converted by the MasterCam software package into CNC machine language. A one-half

inch ball milling machine was used to mill the models out of blocks ofUHMD plastic. This

process ensured that the models were replicas of the designs. All three models were designed

with a scale of one inch equals one foot. (i.e. an inch on the model represents one foot on the full

size design.)

Wind Tunnel Testing: The testing procedure took place at Messiah College, Frey hall room 45. A balance was

set up underneath the sub-sonic wind tunnel. The balance allowed drag forces, and surface area

resistance to be measured. The balance is calibrated to measure

the force (in newtons) needed to overcome the wind force. These measurements were taken at

various speeds within the operating range of the super mileage car. The wind speed was

determined through the use of a static pito tube. The results of the designs were then plotted

against each other to appraise a relationship in determining which design minimizes drag and

surface area resistance at the speeds in which the car operates. Since all of the models had

different weights a true measure of deflection is impossible to obtain. This is especially true at

slower wind speeds. A method of weighing each model with respect to the others was developed

to balance out these differences in weight. (Appendix B)

After analyzing the results of the wind tunnel test it was determined that model two was

the most efficient at combating the negative aerodynamic effects over the range in which the car

is designed to operate. This was chosen as the exterior shell design for the super mileage car.

Frame Design: A frame was then designed to fit within the confines of the exterior shell. This frame had

to be designed to handle the various loads and torque's it would undergo while in use. Materials

needed to meet the design requirements were considered. These materials had to also meet the

requirements of ease of workability, ease of welding, overall frame weight, and cost. Using the

Advanced Solids Modeling Extension ofAutoCad Release 11 this process was made simple.

Although an aluminum alloy frame would weight 2/3 of a cro-moly steel frame, it would also cost

three times as much. For this reason 4130 cro-moly steel tubing was chosen. (Appendix C)

A three wheel design was determined to meet the needs of the design. This design used

the front two wheels to steer while the back wheel acted as the drive wheel. To help keep cost low

three junked bicycles were obtained and the forks and heads were used.

The tubing was cut to length and the ends were drilled with a one inch hole saw to give the tubing

a better fit, thus increasing the weld strength. The tubes were then welded together in the shape of

the frame. Due to its superior weld strength. Tungsten Inert Gas (TIG) welding was used initially

to bond the various tubes, however this process is very time consuming, so in the interest of

saving time. Metal Inert Gas (MIG) welding was used on the majority of the tubing joints.

The forks and wheels were assembled and a simple steering mechanism was established.

This frame was then pulled behind a car to determine its safety at the speeds in which the car

would operate. Originally the designed called for 27 "x 1" bicycle wheels. Due to their large

rolling surface efficiency would be greatly increased. However, after the pull test it was

determined that at speeds greater than 20 miles per hour on turns of 45 degrees or more the frame

had a tendency to tip. This was impart due to the high center of gravity of the frame. With safety

in mind smaller wheels (16"x 1.75") were chosen for the front, while the back wheel was

submerged into the frame. The frame was again pulled behind a car with dramatically better

results. The frame could now handle comers of 60 degrees at speeds of 40 miles per hour.

Steering: A simple, low weight steering mechanism was designed. It consists of two bicycle stems

with 1/8" steel bar stock clamped inside. A 3/8" steel rod was cut and threaded at both ends. 3/8"

x 24 x 3/8" rod end bearings were screwed onto each end. This rod was then fastened to the bar

stock with 3/8" machine bolts, and washers. The rod was twisted until the wheels were aligned

parallel with each other. Small chain was attached to the bar stock and to the frame to limit the

angle at which the steering could turn. This in turn, prevents the driver from making turns that

would cause the frame to tip or skip out.

Engine Mounts:

A flat surface had to be established on which to mount the engine. 1/8" x 1.5" low

carbon steel, angle iron was used for this purpose. The distance between the engine mounting

holes was determined and the angles were welded and drilled accordingly. The engine was

attached with 5/16" x 1.5" machine bolts.

Jack shaft Mounts: Again, a flat surface had to be established to mount the jack shaft and the driven portion

of the transmission. This surface also needed to be perpendicular to the engine shaft for proper

operation of the transmission. 1/8" x 1.5" angle was also used for this application. The jack shaft

supports were welded to 1/4" x 3" angle to allow proper driven unit clearance. The shaft

supports were mounted to the angle by means of 3/8" x 3/4" machine bolts.

Seats: 1/4" plywood was used for the seating arrangements. A foot rest was cut as well as a

seat. These members were attached to the frame with 3/4" conduit hangers.

Exterior Frame (Shell): To give the frame the desired exterior (shell) shape, a series of 1/8" x 3/4" aluminum

bars were bent. These bars were attached to the frame with 3/4" conduit hangers . They act as

the ribs of the exterior frame by giving the frame the contours of design #2. A center rib was

also attached with rivets to increase the stiffness of the exterior ribs.

Exterior Coverings:

The ribs needed to be covered with a material that would give a smooth surface finish, as

well as allow good visibility. For these reasons, heat shrink plastic was chosen. The plastic was

put on the front and very rear sections of the rib structure. After heating with a hair dryer the

surface becomes very smooth, and helps to tie all the ribs together. For the second rear section of

the frame, aluminum sheet roll was used. This material was chosen due to the heat coming of the

engine and exhaust. These aluminum sections were attached with Velcro to aid in their removal

if any work need to be done to the engine. The third rear section of the car was covered with four

Mil Polyethylene. The side near the engine was insulated with 1/2" duct insulation (R-vahie 4.3)

to prevent possible melting. These sections were also attached with Velcro to allow the driver to

enter the interior of the frame.

Engine Design: The engine selected was a Briggs and Stratton eight horsepower. The engine has

a horizontal counter-clockwise rotating shaft. The engine block is cast aluminum which will

reduce the weight of the engine as compared to a cast iron engine. Following is a list of the

engine specifications currently available:

Model 190432

- recoil start

-1" x 3 21/32" shaft 7/16"-20 tapped end

- Ball bearing output shaft

- Tapped bearing plate

- 3600 rpm (unloaded)

- weight 50 pounds

To further increase the efficient operation of this engine some modifications were made. The

modifications are as follows.

Condenser replacement: The conventional condenser and points were replaced with an electronic impulse ignition.

This causes the spark plug to fire 5 to 14 times each impulse. This increases the combustion

process, which in turn will lead to a better gasoline bum. This in turn ensures maximum

explosion per unit of gasoline.

Muffler modification: The conventional muffler was replace with a straight pipe exhaust. This increases the

amount of "spent" air that leaves the chamber, thus allowing more "new" air to enter the chamber.

This in turn creates a greater explosion which leads to more power per unit of gasoline.

Gasoline Vaporization:

Brief History: Since the advent of the internal combustion engine the public has been convinced that the

Air/Fuel ratio of 15:1 is the ultimate mixture for gasoline to bum. However, this is not true.

Gasoline will bum at ratios of as great as 200:1. This in turn means that less fuel is spent for each

fire of the engine. In 1936 Charles Nelson Pogue developed a carburetor that did this. It reduced

the gasoline particles from 500 micron size to 250 micron size. In order to do this, Pogue

developed a carburetor that used the wasted exhaust heat to heat the gas into its vaporous state.

This carburetor was tested by the Canadian division of the Ford Motor Company, and their test

confirmed that the carburetor did in fact get 200 miles per gallon on a 400 cubic inch V-8 engine.

This carburetor was suppressed by the large oil companies for fear that it would take a

considerable chunk of their market. (Less gas needed equals less gas sold equals lower gas prices

equal loss of money) The excess gas which is not burnt is held in the catalytic

10

converter until the exhaust heats it up enough to reduce the micron size to 250, then it passes

through and travel out the muffler into the air. It is like pouring gas into the air.

Vaporization Design: The vaporizer which was built for the super mileage car is based on a design by Arthur C.

Sgrignoli. The designer claims this carburetor will triple existing mileage figures. It consist of a

18 gauge steel six inch cylinder attached on top of a four inch cylinder. (Appendix D) A 1/2"

outside diameter (O.D.) copper tube is tapped into the existing exhaust system. This tube is coiled

inside the large cylinder six times. Two small fuel jets (.036" hole) extend from the bottom of the

small cylinder towards these coils. On top of the large cylinder is a venturi shaped device leading

to a 1/2" heater hose. An air supply entrance is made 1/4" from the bottom of the small cylinder,

and a excess fuel float extends up one inch from the bottom of the small cylinder. The cylinder

must be sealed so that no vapor can escape accidentally. For this reason all entries into the

cylinders were made by tapping holes and screwing brass fittings in. The top venturi is attached

by means of 3/8" x #4 sheet metal screws as well as a high temperature gasket. All welds were

checked to ensure no leaks were present.

Vaporization Operation: The exhaust heat coming out of the engine ranges between 1000 and 1100 degrees

Fahrenheit. This heat travels through the copper tubing coils inside the vaporizer. Gasoline

vaporizes at various temperatures according to the octane and additives. 87 octane has the lowest

vaporization point at 423.7 degrees Fahrenheit. The tubing will easily reach this temperature in a

short time of operation. The fuel jets spray a mist of gasoline onto these hot coils. The majority of

the gas is vaporized. The remaining gasoline falls into the bottom of the vaporizer. This process

continues until the gasoline in the bottom of the vaporizer reaches a level of one inch. When this

occurs the float valve

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opens allowing the excess gas to exit and be reused. Since the liquid gas is hot it runs through a

copper pipe open to the outside air. This in turn cools the gas before it enters the suction side of

the fuel pump. The Briggs engine was not equipped with a fuel pump. It is a gravity fed fuel

system. A small pump was therefore installed which runs off the pressure in the engine crankcase.

This pump pushes the fuel at seven pounds per square inch. The air is drawn through the

vaporizer when the piston pulls down. This air is bubbled through a fine screen so as to disperse it

throughout the vaporizer. The vaporous mixture is drawn through the existing carburetor into the

chamber. By doing this the existing throttle linkage can be used to control how much vapor is

burned. Since the vaporizer takes a minute to get warm the existing carburetor is used for start up.

After heat is achieved the existing carburetor turned off by means of a valve in the gas line. At the

same time the vaporizer valve is opened. By doing this, with two separate valves the engine will

continue to run without the risk of flooding. The engine speed is controlled by a hand throttle

located in front of the steering . Another benefit to the vaporous mixture is that after it is burnt the

particles leaving are already small enough to exit, thus eliminating the need for a horsepower

restricting catalytic converter. The engine emissions are also cleaner than with a conventional

carburetor and muffler.

Transmission: The transmission chosen to drive the car is a Comet 30 series torque converter. It consists

of a belt, and two variable pitch pulleys. It has a driver piece which is attached to the engine, and

a driven piece which is attached to the jack shaft. A Comet belt with a nine and 1/4" center to

center length connects the driver and driven units. As the engine revolutions increase the

centrifugal force allows the belt to move to a smaller radius circle thus automatically "shifting"

the transmission into a higher gear. This allows the car to optimize propulsion in proportion to

engine speed. Also attached to the jack shaft is a 18 tooth sprocket. A # 35 chain is connected

between this sprocket and a 44 tooth sprocket

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which is fixed to the rear wheel. When the belt turns the rear driver the jack shaft and sprocket

also turn. This in turn rotates the rear sprocket thus propelling the car forward.

Braking: Braking for the car is accomplished by a side pull caliber style bicycle brake positioned

on the back wheel. A squeeze type brake lever is positioned next to the driver so that braking can

be accomplished whenever necessary.

Speed Monitoring Devices: A Cateye Micro bicycle cyclometer is attached to the rear wheel of the car. This mini-

computer allows the driver to keep track of present and average speed, time and distance

traveled, and maximum speed. It is positioned such that the driver can see it whenever he

chooses to. This is important for maintaining a average speed as required by the project

specifications.

Safety Devices: With the concept of safety in mind, a fire extinguisher was mounted in such a way that it

is directed at the engine. If a fire would happen to start the operator can then pull a cord and

release the flame retardent thus putting out the fire.

The engine is also equipped with a kill switch on the steering mechanism, by simply

flicking the switch the engine is grounded out and stops.

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Testing and Results: The completed super mileage car underwent several test. The first being a performance

test. The test took place at Rossmoyne Industrial Complex, in Mechanicsburg, PA on April 26,

1994. The park has a two mile road that completes a loop. The elevation change is less than 50

feet. The car was driven by the designer who has a weight of 205 pounds. The test tested the

existing carburetor for gas mileage. The vaporizer was left off for the entire test. The driver

drove the car 31.6 miles with an average speed of 31.4 miles per hour. This distance used .2

gallons (25.6 fluid ounces) of gasoline. That equates to 158 miles per gallon.

The second test took place at the same location on April 27,1994. This test was to use the

vaporizer. This time the driver drove the car 45.3 miles with an average speed of 30.6 miles per

hour. This distance used the . 1 gallons (fluid ounces) of gasoline. That equates to 453 miles per

gallon.

The final test took place on April 28, 1994. This was an open road test with elevation

changes as much as 250 feet. On this test is was much harder to maintain an average speed in the

same area as the two previous test. The existing carburetor was used for this test. The driver

drove the car 7.4 miles with an average speed of 24.6 miles per hour. This test used .06 gallons

(7.68 fluid ounces) of gasoline. This equates to 123.3 miles per gallon.

The open road test used more gasoline primarily to overcome the need for rapid

acceleration to maintain speed when going up hills.

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Conclusions: Through the combination of the an aerodynamically efficient body, gasoline

vaporization, and a light yet sturdy frame a one passenger car propelled by a eight horsepower

Briggs and Stratton engine, that can maintain an average speed of 31.0 miles per gallon while

achieving 453 miles per gallon of gasoline under level driving conditions. The gasoline

vaporizer significantly increased the fuel efficiency of the engine. A 2.867 increase in fuel

efficiency was achieved which is almost the 3 time increase the designer claims.

15

Suggestions: The nature of this project proved very difficult for a one person team to handle. The

project had so many parts that it was difficult for the designer to cover each aspect completely. In

retrospect this project would be excellent for a team of designers to tackle. Possible improvement

would be made in the following areas:

1. The cockpit was rather small, although the 205 pound driver did fit in. A more upright

sitting position would be preferred.

2. The chain came off during the rapid accelerations of the open road test. This problem could be solved in two ways. A chain idler arm could be attached with a spring

so as to keep tension on the chain at all times. The second solution could involve a

different fork on the rear that would allow the wheel to be slid back, thus removing the

chain slack.

3. The steering was very sensitive due to the narrow wheel base. A wider wheel base would

solve this problem easily.

4. Various vaporizer designs could be tested to determine if the design chosen was truly the

best.

5. A disc or drum type brake might be place on the rear wheel instead of the caliper type brake.

This would ensure good stopping distance.

In conclusion, this was an excellent project for teaching the designer how to think, and

plan for himself.

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Cost Summary:

Following is a listing of the cost incurred in the super mileage car project:

Item 8 Hp Briggs and Stratton Engine Torque Converter-Driver Torque Converter-Driven Torque Converter- Belt Jack Shaft Kit 44 Tooth Sproket #35 Chain (5 feet) 3 Junked Bicycles Cro-Moly Tubing (52 feet) 3/4" Conduit Hangers Vaporizer Sheet Metal Vaporizer Weld Assorted Brass Fittings 1/2" Copper Tubing (10 feet) 1/4" Fuel Hose (3 feet) 1/2" Hose (2 feet) Assorted Hose Clamps Bicycle Cyclometer Aluminum Coil stock (24" x 10') Shrink Wrap Plastic 4 MIL Plastic Sheet Throttle Cable Assorted Fastners 1/8" x 3/4" Aluminum Bar Gasket Material (8" x 8") 1" Exhaust Pipe (2')

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Total

Cost $297.64

$70.24 $62.50 $13.10 $24.95 $16.25 $10.60 $25.00

$102.78 $7.50

$23.00 $25.00 $40.62

$7.99 $4.00 $3.13 $3.54

$30.00 $25.57

$8.40 $2.99 $5.97 $4.00

$54.78 $1.30 $2.51

$873.36

Vendors listing:

Following is a list of vendors used and their addresses:

1. Norther Hydraulics

P.O. Box 14999 Bumsville, MN 55337-0499

2. Kart World 1488 Mentor Avenue Painesville, Ohio 44077

3. Bob's Outdoor Power Center 640 Alpine Road Lewisberry, PA 17339

4. R.F.Fager 2056 State Road Camp Hill, PA 17011

5. Hechinger Camp Hill, PA 17011

6. Pep Boys #21 6100 Carlisle Pike Mechanicsburg, PA 17022

7. Dillsburg Aeroplane Works 125 Saw Mill Rd Dillsburg, PA 17019

8. Rich's Bike Shop 1589LisbumRd. WellsvUle,PA17017

9. Garron Plastics of P.A. 1123 Chambers Hill Road Harrisburg, PA 17022

10. Obermeyers Sheet Metal 5 Plum St. Lemoyne, PA

18

Bibliography:

Fluid Mechanics. Riley and Zachary, John Wiley and Sons, New York, 1989.

Secrets of the 200 MPG Carbeurator Book I, Alan Wallace, H and A industries, Bowling Green, MO, 1980

Secret of the 200 MPG Carbeurator Book II, Alan Wallace, H and A industries, Bowling Green, MO, 1982

Secrets of the 200 MPG Carbeurator Book III, Alan Wallace, H and A industries, Bowling Green, MO, 1982

Popular Mechanics, September 1993, pi 03 and 130.

Fundamentals of Machine Component Design, Juvinall and Marshek, John Wiley and Sons, New York, 1991

19

Appendix A

Appendix B

WIND TUNNEL MODEL RESULTS

DESIGN #1 Wind Tunnel Speed

(meters/sec)

0 0.00 0.000 0.000 3 6.72 0.020 0.020 5 11.20 0.050 0.050 8 17.92 0.085 0.085 9 20.16 0.100 0.100 10 22.40 0.135 0.135 11 24.64 0.150 0.150 12 26.88 0.210 0.210 13 29.12 0.251 0.251 14 31.36 0.282 0.282 15 33.60 0.324 0.324 16 35.84 0.361 0.361 17 38.08 0.405 0.405 18 40.32 0.440 0.440

Wind Tunnel Speed

(miles/hour)

Deflection

(Newtons)

Weighted Deflection (Newtons)

WIND TUNNEL MODEL RESULTS

DESIGN #2 Wind Tunnel Speed

(meters/sec)

0 0.00 0.000 0.000 3 6.72 0.004 0.004 5 11.20 0.009 0.009 8 17.92 0.051 0.052 9 20.16 0.078 0.080 10 22.40 0.085 0.087 11 24.64 0.110 0.113 12 26.88 0.127 0.130 13 29.12 0.140 0.144 14 31.36 0.160 0.164 15 33.60 0.171 0.175 16 35.84 0.222 0.228 17 38.08 0.238 0.244 18 40.32 0.275 0.282

Wind Tunnel Speed

(miles/hour)

Deflection

(Newtons)

Weighted Deflection (Newtons)

WIND TUNNEL MODEL RESULTS

DESIGN #3 Wind Tunnel

Speed (meters/sec)___

0 0.00 0.000 0.000 3 6.72 0.011 0.012 5 11.20 0.032 0.035 8 17.92 0.057 0.063 9 20.16 0.075 0.083 10 22.40 0.090 0.099 11 24.64 0.119 0.131 12 26.88 0.123 0.135 13 29.12 0.149 0.164 14 31.36 0.190 0.209 15 33.60 0.208 0.229 16 35.84 0.253 0.278 17 38.08 0.298 0.328 18 40.32 0.475 0.523

Wind Tunnel Speed

(miles/hour)

Deflection

(Newtons)

Weighted Deflection (Newtons)

Appendix C

Appendix D