FORMULAS

  • Conversion: 1 Liter = 61.02 Cubic Inches


  • HorsePower from MPH = (.00426 * MPH)^3 * WEIGHT

    Example: MPH=94 WEIGHT=3550 gives us: 227hp

  • ET from HorsePower = (WEIGHT / HP)^.333 * 5.825

    Example: WEIGHT=3550 HP=227 gives us: 14.55sec 1/4 mile

  • CFM = (CID/2)*(RPM/1728)*VE

    Example: CID=305 RPM=4500 VE=.75 gives us: 297cfm

    VE = volumetric efficiency
    VE is appoximately equal to 0.8 for hi-perf street engine 
    and approx. equal to 0.9+ for full race engines.
    This gives rather low values for CFM but is probably all you really need.
    
  • TORQUE = (5245 * HP) / RPM

    Example: HP=227 RPM=4500 gives us: 264lb/ft

  • HorsePower from MPH = WEIGHT * (MPH/234)^3

    Example: WEIGHT=3550 MPH=94 gives us: 230hp

  • HorsePower from ET = WEIGHT * (5.825/ET)^3

    Example: WEIGHT=3550 ET=14.55 gives us: 228hp

  • Tire height (inches) = {[(section width * profile) / 2540] + (wheel diameter / 2)} * 2

    Example: (255/60R15) gives us: 27.04" (larger than factory size)

    Example: (245/60R15) gives us: 26.57" (larger than factory size)

    Example: (235/60R15) gives us: 26.10" (same as factory size)

    Example: (225/60R15) gives us: 25.62" (smaller than factory size)

    Example: (215/65R15) gives us: 26.00" (factory size)

    Example: (275/50R15) gives us: 25.82" (very close to factory size)

  • 60 foot time from ET = (.12 * 1/4 mile et) + .17

    Example: 60' time = (.12 * 14.90) + .17 = 1.958 seconds

  • Top Speed (mph) = (see example)

    Example:

    	Redline = 5400
    	Top Gear (trans) = 0.67:1
    	Rear end gear = 3.73:1
    	Tire height = 27"
    	PI = 3.14
    	
    5400/0.67 = 8059.70 driveshaft RPM
    
    8059.70/3.73 = 2160.77 wheel RPM
    
    2160.77*27*3.14 = 183190.08 inches/minute
    
    183190.08*60 = 10991404.80 inches/hour
    
    10991404.80/12 = 915950.40 feet/hour
    
    915950.40/5280 = 173.47 MPH
    
    * This number assumes no resistance of any kind. This top speed is theoretical.
    You will certainly never actually see this top speed in your car, but it is useful to 
    determine a ballpark limit. Using this number you can factor in rolling
    friction and wind drag to get a closer number.
    


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