Pages: 1
Here ya go, here is a tech articel for ya!
(Click here to view the original thread with full colors/images)
Posted by: John
i emailed a copy to you too Evil. you should post it on the articles page!
These equations are taken from Auto Math Handbook by John Lawlor
- For further explination of equations, please refer to the book published by HPBooks.
- These equations are pretty much self-explanatory. There is necessary explinations were needed.
- As with all mathematical equations, the rules, symbols and theories of math apply in all respects. symbols have been changed where necessary but a legend of changed symbols has been provided
Some nomenclature descriptions
- There are two ways to list division in this document
one is: 4/5 reads as Four Divided by Five
the other is: 4 which also reads 4 divided by five
5
- This ^ is called a carat. In these equations it is used to show that a number that follows another number or term is to be the power of that term.
for example: four squared will be written as so 4 ^ 2
six cubed will be written as so 6 ^ 2
stroke squared will be written as so stroke ^ 2
- Since my HTML editor does not support a square root symbol, i will use th following nomeclature for a square root symbol: SR/
for readability purposes, square roots will look like this (SR/ [4.5/6.2] *3)
this reads as follows multiply the result of the equation 4.5/6.2 by 3 and then take the square root of that result
a cubed root will be written as such 3CR/
Piston Displacement
Cylinder Volume = pi/4 x bore ^ 2 x stroke
Rounding Up or Down
- To figure out actual displacement and whether or not you have a 4.9L or a 5.0L
Displacement = 0.7853982 x bore ^ 2 x stroke x Number of cylinders
Overboring
Displacement = 0.7853982 x (bore + overbore difference) ^ 2 x stroke x Number of cylinders
the bore + overbore difference would look like this
3 in bore + .030 overbore = 3.03 which is then squared and multiplied by stroke and cylinder count
Stroke
Stroke = displacement
(pi/4 x bore ^ 2 x no. of Cylinders)
Bore
Bore = (SR/ displacement / (pi/4 x stroke x no. of cylinders) )
Calculating Compression Ratio
Compression ratio = Cylinder + Chamber Volume
Chamber Volume
Calculating Chamber Volume
Chamber Volume = Cylinder Volume
Compression Rato - 1.0
Milling Heads
Amount to Mill = [(new disp. ratio - old disp. ratio) / (new disp. ratio x old disp. ratio)] x stroke
Mean Piston Speed
Piston Speed in fpm = (2 x stroke in inches x rpm) / 12
Rev Limits
RPM = (piston speed in fpm x 6) / stroke in inches
Calculating Horsepower (Brake)
Horsepower = rpm x torque
5252
Calculating Torque
Torque = (5252 x horsepower)
rpm
Power Loss due to Elevation
bhp loss = elevation in feet x 0.03 x bhp at sea level
1000
Air Capacity (yeilds Cubic Inches per Minute)
Air Capacity = rpm x displacement
2
CFM (Cubic Feet per Minute of Air Capacity)
CFM = rpm x displacement
2 x 1728
Volumetric Efficiency
V.E. = actual CFM x 100
theoretical cfm
- to obtain the theoretical CFM figure, use the CFM calculation above.
Carburetor Size (Street and Strip)
Street Carb cfm = rpm x displacement x 0.85
3456
Race Carb cfm = rpm x displacement x 1.1
3456
Vehicle Weight Distribution
- This is applicable if you have access to a lage enough scale.
- Use this equation to weigh the amount of weight on each axle by weighing one axle on the scale at a time. You can also use rough guesstimates but that sacrifices accuracy.
- This equation is also applicable for left/right distribution. To get the weight on wheels number, weigh only one side of the car at a time and perform the calculation.
Wheel Weight Percentage = weight on wheels x 100
overall weight
Adding Weight
- This can be used for a vraiety or reason including off-roading, trailer towing, payload capacities and of course better weight balance for racing
Wheel Weight Increase = [(weight on wheels/wheelbase) x weight to be added] + weight to be added
Center Of Gravity
CG behind front wheels = (rear wheel weight / overall weight) x wheelbase
CG location off-center to heavy side = (track / 2) - (weight on light side / overall weight) x track
CG height = (level wheelbase x raised wheelbase x added weight on scales)
distance raised x overall weight
- for the CG Height requirement, please refer to the book for better description.
Drive Wheel Torque
drive wheel torque = flywheel torque x first gear ratio x final drive ratio x 0.85
Wheel Thrust
wheel thrust = drive wheel torque
wheel rolling radius in feet
Calculating g-Force
g-Force = wheel thrust
weight
weight transfer = weight x cg height x g-Force
wheelbase
Lateral Acceleration
lateral acceleration = (2.0 x pi) ^ 2 x radius
time ^ 2
- To find lateral acceleration directly in g-Force, the value of 1.0 g per second per second (32.174) must be entered into the above equation like so:
lateral acceleration = (2.0 x pi) ^ 2 x radius
32.174 time ^ 2
Lateral Weight Transfer
lateral weight transfer = weight x cg height x lateral g-Force
average wheel track width in inches
Centrifugal Force
centrifugal force = weight x lateral g-Force
Shift Points
RPM After Shift = ratio shift into x rpm before shift
ratio shift from
Driveshaft Torque
driveshaft torque = flywheel torque x tranmission ratio
1/4 Mile ET
ET = (3CR/ {weight/hp} ) x 5.825
Power or Weight from ET
HP = weight
(ET/5.825) ^3
Weight = (ET/5.825) ^ 3 x hp
Miles Per Hour
MPH = (3CR/ {hp/weight} ) x 234
Power or Weight from MPH
HP = (mph/234) ^ 3 x weight
weight = (234/mph) ^ 3 x hp
Gearing for 1/4 Mile Speed
Overall Gear Ratio (manual transmission) = tire diameter x rpm
340 mph
Overall Gear Ratio (automatic transmission) = tire diameter x rpm
335 mph
Instrumentation Error
- Speedometer Check
Actual MPH = 3600
seconds per mile
Speedo Error Percent = difference between actual and indicated speeds x 100
actual speed
- Odometer Error
Indicated Distance = reading at finish - reading at start
Percent Error = difference between actual and indicated distances x 100
actual distance
MPH From Tire Size
MPH = rpm x tire diameter
gear ratio x 336
RPM From Tire Size
RPM = mph x gear ratio x 336
tire diameter
Overall Gear Ratio from Tire Size
Gear Ratio = rpm x tire diameter
mph x 336
Tire Diameter
Tire Diameter = mph x gear ratio x 336
rpm
Tire Sizing
- Metric Tire Diameter
Tire Diameter = 2 x section width x aspect ratio + rim diameter
25.4 100
- Effective Drive Ratio
Effective Ratio = old tire diameter x original ratio
new tire diameter
- Equivalent Drive Ratio
Equivalent Drive Ratio = new tire diameter x original ratio
old tire diameter
- Speedometer Correction
Actual MPH = new tire diameter x indicated mph
old tire diameter
Indicated MPH = old tire diameter x actual mph
new tire diameter
Average MPH and MPG
- MPH
miles per gallon = miles
gallons
- Miles
miles = miles per gallon x gallons
- Gallons
gallons = miles
miles per gallon
- Average Miles Per Hour
miles per hour = miles
hours
- Miles
miles = miles per hour x hours
- Hours
hours = miles
miles per hour
- Raceway Miles Per Hour
RMPH = miles x 3600
seconds
-Seconds
seconds = miles x 3600
miles per hour
Blood Alcohol Concentration
BAC = (ounces consumed x %alcohol x 0.075) - (hours x 0.015)
body weight
Posted by: John
ok, so it didn't cut and paste so well. read teh article when Evil posts it on teh article page.
Posted by: John
hey Evil, i'm not happy with the way that article turned out on the page. i'm going to see if i can't build an HTML file from the document. i'll send a better one when i get to together.
Posted by: John
yeah, thats what i figured. i have an HTML document at work. just gotta make sure teh equations are all correct and i'll email you the document. it'll be ready to go with the colors and stuff too so all you will have to do is name it what you named the other one and overwrite it
Posted by: John
i don't have the header and footer. i was just going to do all the formatting to the page for the text so you wouldn't have to worry about it. i can grab it and stick it in there though.
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