PORSCHE RACING HISTORYMark Altman (USA)
1986
24 August 1986 - Road America 500 Miles - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 31 | Porsche 914/6 | GTU | Gary Altman (USA)/Mark Altman (USA) | Altman Bros. Motor Racing (USA) | 27th | 6th | 60th | 101 laps |
5 October 1986 - Columbus IMSA GT - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 31 | Porsche 914/6 | GTU | Mark Altman (USA) | Altman Bros. Racing (USA) | 21st | 8th | 30th | 29 laps |