Free Ground shipping in the Contiguous US for orders over $250
| Alternator Pulley Diameter | Crankshaft Pulley Diameter | ||||||||||
| 5.0" | 5.25" | 5.5" | 5.75" | 6.0" | 6.25" | 6.5" | 6.75" | 7.0" | 7.5" | 8.0" | |
| 1.9" | 2.63 | 2.76 | 2.89 | 3.03 | 3.16 | 3.29 | 3.42 | 3.55 | 3.68 | 3.95 | 4.21 |
| 2.0" | 2.50 | 2.63 | 2.75 | 2.88 | 3.00 | 3.13 | 3.25 | 3.38 | 3.50 | 3.75 | 4.00 |
| 2.2" | 2.27 | 2.39 | 2.50 | 2.61 | 2.73 | 2.84 | 2.95 | 3.07 | 3.18 | 3.41 | 3.64 |
| 2.4" | 2.08 | 2.19 | 2.29 | 2.40 | 2.50 | 2.60 | 2.71 | 2.81 | 2.92 | 3.13 | 3.33 |
| 2.5" | 2.00 | 2.10 | 2.20 | 2.30 | 2.40 | 2.50 | 2.60 | 2.70 | 2.80 | 3.00 | 3.20 |
| 2.75" | 1.82 | 1.91 | 2.00 | 2.09 | 2.18 | 2.27 | 2.36 | 2.45 | 2.55 | 2.73 | 2.91 |
| 3.0" | 1.67 | 1.75 | 1.83 | 1.92 | 2.00 | 2.08 | 2.17 | 2.25 | 2.33 | 2.50 | 2.67 |
| 3.25" | 1.54 | 1.62 | 1.69 | 1.77 | 1.85 | 1.92 | 2.00 | 2.08 | 2.15 | 2.31 | 2.46 |
| 3.5" | 1.43 | 1.50 | 1.57 | 1.64 | 1.71 | 1.79 | 1.86 | 1.93 | 2.00 | 2.14 | 2.29 |
| 4.0" | 1.25 | 1.31 | 1.38 | 1.44 | 1.50 | 1.56 | 1.63 | 1.69 | 1.75 | 1.88 | 2.00 |
|
The pulley ratio is the diameter of the crankshaft pulley divided by the diameter of the alternator pulley. |
|
Multiply that number times the engine RPM to get the alternator RPM. |
|
For example, a 6 inch crankshaft pulley and a 2 inch alternator pulley equals a pulley ratio of 3:1. |
|
Three times an engine speed of 800 RPM equals 2,400 alternator RPM. High Output Alternators require 2400 alternator RPM's to start the charging process. |
