| top opening | Setback | |
| 1) Bob Newberry started removing material from bottom of front plate, to relive built up pressure in between rotors |
14-71 (15.31") |
None |
| 2) SCS introduces the HH - "retro" blower around 1987. |
14-71 |
|
| 3) Through the 90s other companies start making HH - "retro" blowers. |
14-71 |
|
| 4) 1999 SSI builds the D rotor with a small top. |
Small | |
| 5) 2002 Kobelco makes k8 rotors and releases the superman for overdrive restricted classes. |
Small | |
| 6) Littlefield K8, Kobelco K8s, Kobelco K8 Superman, SSI d-rotor |
Small | |
| 7) 2008 Kobelco makes K11 rotor (superman), |
Small | |
| 8) DMPE modded supermans, DMPE m5,, |
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| 9) Littlefield M - LB |
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| 10)SSI F (HH) series - F2, F3, F4, F5 |
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| 9) PSI (roots-HH) |
Several | 1", 1.5". 2" |
| 10) Fowler F-11 (was K-11 superman) |