12 13 14 15 16 17 18 19 20
53 4.42 4.08 3.79 3.53 3.31 3.12 2.94 2.79 2.65
54 4.50 4.15 3.86 3.60 3.38 3.18 3.00 2.84 2.70
55 4.58 4.23 3.93 3.67 3.44 3.24 3.06 2.89 2.75
56 4.67 4.31 4.00 3.73 3.50 3.29 3.11 2.95 2.80
57 4.75 4.38 4.07 3.80 3.56 3.35 3.17 3.00 2.85
58 4.83 4.46 4.14 3.87 3.63 3.41 3.22 3.05 2.90
59 4.92 4.54 4.21 3.93 3.69 3.47 3.28 3.11 2.95
60 5.00 4.62 4.29 4.00 3.75 3.53 3.33 3.16 3.00
61 5.08 4.69 4.36 4.07 3.81 3.59 3.39 3.21 3.05
62 5.17 4.77 4.43 4.13 3.88 3.65 3.44 3.26 3.10
63 5.25 4.85 4.50 4.20 3.94 3.71 3.50 3.32 3.15
64 5.33 4.92 4.57 4.27 4.00 3.76 3.56 3.37 3.20
65 5.42 5.00 4.64 4.33 4.06 3.82 3.61 3.42 3.25
66 5.50 5.08 4.71 4.40 4.13 3.88 3.67 3.47 3.30
67 5.58 5.15 4.79 4.47 4.19 3.94 3.72 3.53 3.35
68 5.67 5.23 4.86 4.53 4.25 4.00 3.78 3.58 3.40
69 5.75 5.31 4.93 4.60 4.31 4.06 3.83 3.63 3.45
70 5.83 5.38 5.00 4.67 4.38 4.12 3.89 3.68 3.50
71 5.92 5.46 5.07 4.73 4.44 4.18 3.94 3.74 3.55
72 6.00 5.54 5.14 4.80 4.50 4.24 4.00 3.79 3.60
73 6.08 5.62 5.21 4.87 4.56 4.29 4.06 3.84 3.65
RPM Desired (Ask Engine Builder )
RPM Car Ran (From Last Run)
Current Gear Ratio Being Used In The Car (See Ratio Chart)
What you will get from the formula is a new gear ratio to put into the car to achieve the RPM's that you desire.
Here is the formula:
RPM Wanted ÷ RPM Ran x Gear Ratio Ran = New Gear Ratio Needed
Example:
4950 ÷ 5150 x 4.13 = 3.96
RPM Wanted: 4950
RPM Ran: 5150
Current Ratio In Car: 4.13
New Gear Ratio Needed To Reach 4950: 3.96
Please Note: You will not always achieve an exact ratio that would be found on your gear ratio chart. Use the appropriate engine and axle gears to obtain a ratio that is closest to the new ratio you want to use.
