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Old 06-21-2013, 11:31 PM   #19
snymat68

 
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Drives: 2013 Blue Ray 1LS M6
Join Date: Apr 2013
Location: Pittsburgh, PA
Posts: 1,223
These numbers are for my '13 1LS M6 with 18" wheels. Change out the bold numbers for your own and recalculate.

The math...

KNOWNS
A = Vehicle Speed (in mph)
B = Wheel Radius (in inches) measured from the wheel center to the ground
C = Rear Differential Ratio (ie 3.27)
D = Transmission Gear Ratio (ie .84)

VEHICLE - Convert MPH to in/min
(80mi/1hr) x (5280ft/1mi) x (12in/1ft) x (1hr/60min) = 84,480 in/min

WHEEL - Convert radius to circumference
C = 2πr = (2) x (π) x (13.75in) = 86.39 in = 86.39 in/1 rev

WHEEL - Convert in/rev to RPM
(84,480in/1rev) x (1rev/86.39in) = 977.89 RPM (at the wheel)

RPMs - Work it backwards through the drivetrain
(Wheel RPM) x (Differential Ratio) x (Transmission Gear Ratio) = Engine RPM
(977.89) x (3.27) x (.84) = 2,686 RPM
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Performance Mods
Elite Catch Can | CAI Intake with Scoop & Washer Bottle Relocation | MRT v2 Axle-Back Exhaust | MagnaFlow Resonated X-Pipe | Resonator Delete | Vmax Ported Throttle Body | GM Strut Tower Brace | JDP Tow Hook | Vitesse Throttle Controller
Aesthetic Mods
Chrome Peek-A-Boo Door Handles | Interior Accessories Kit | OEM RS HIDs w/ 6000k Bulbs & 5000k LED Fogs | Tail Light, Marker Light, & Turn Signal Tint | Tru-Sequence Sequential Turn Signals & Brake Lights | Silver Fade Gill Stripes | Carbon Fiber Bowties | Various Chrome/Painted/Carbon Fiber Items

Last edited by snymat68; 06-22-2013 at 12:32 AM.
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