This chart is included in our Website for reference purposes. The weights listed are for production, unmodified rotors.
| Engine | Year | Compression | Weight (Grams) | Weight (Pounds) |
| 12A | 76-82 | 9.4 | 4603 | 10.15 |
| 12A | 83-85 | 9.4 | 4353 | 9.60 |
| 13B | 74-78 | 9.2 | 5253 | 11.58 |
| 13B | 84-85 | 9.4 | 5253 | 11.58 |
| 13B N/T | 86-88 | 9.4 | 4553 | 10.04 |
| 13B Turbo | 86-88 | 8.5 (38cc Combustion Pocket) |
4553 | 10.04 |
| 13B N/T | 89-92 | 9.7 (26cc Combustion Pocket |
4328 | 9.54 |
| 13B Turbo | 89-92 | 9.0 | 4328 | 9.54 |
| 13B T/T | 93-95 | 9.0 | 4328 | 9.54 |
| 13B Renesis | 04-on | 10.0 | 4218 | 9.30 |
NOTE: Weights are approximate, and include rotor bearing, but do not include any seals or springs. Please remember, the weights are APPROXIMATE — it is not uncommon at all to get a 50+ gram spread in a pair of NEW rotors. A batch of NEW 89-92 Non-turbo rotors we weighed will give you a good example (in grams): 4235, 4251, 4278, 4282, 4284, 4307, and 4314 = 79 gram spread (and none were at the 4328 one we used for the above chart).
When assembling an engine we strongly recommend having it balanced, or at the least be sure your rotors are close in weight.