PORSCHE RACING HISTORYPreston Henn (USA)
1979
4 February 1979 - Daytona 24 Hours - World Championship for Makes
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 93 | Porsche 934 | 930 670 0173 | GTO | Dale Whittington (USA)/R. D. Whittington (USA)/Preston Henn (USA) | Whittington Bros. Racing (USA) | 29th | 11th | 35th | 389 laps - Accident |
4 February 1979 - Daytona 24 Hours - World Championship for Makes
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 00 | Porsche 935/77A | 930 890 0021 | GTX | Preston Henn (USA)/Ted Field (USA)/Danny Ongais (USA) | Interscope Racing (USA) | 61st | 19th | 11th | 29 laps - Accident |
17 March 1979 - Sebring 12 Hours - World Challenge for Endurance Drivers
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 09 | Porsche 935/77A | 930 890 0021 | GTX | Hurley Haywood (USA)/Preston Henn (USA)/Peter Gregg (USA) | Thunderbird Swap-Shop (USA) | 26th | 9th | 2nd | 157 laps - Engine |
8 April 1979 - Road Atlanta 100 Miles - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 09 | Porsche 935/77A | 930 890 0021 | GTX | Preston Henn (USA) | Thunderbird Swap Shops (USA) | 19th | 10th | 11th | 33 laps |
22 April 1979 - Riverside 6 Hours - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 09 | Porsche 935/77A | 930 890 0021 | GTX | Bob Bondurant (USA)/Preston Henn (USA) | Thunderbird Swap Shop (USA) | 35th | 12th | 8th | 99 laps - DNF |
29 April 1979 - Laguna Seca 100 Miles - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 09 | Porsche 935/77A | 930 890 0021 | GTX | Preston Henn (USA) | Thunderbird Swap Shop (USA) | 7th | 6th | 13th | 49 laps |
13 May 1979 - Hallett 100 Miles - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 09 | Porsche 935/77A | 930 890 0021 | GTX | Preston Henn (USA) | Thunderbird Swap Shop (USA) | 7th | 7th | 11th | 53 laps |
28 May 1979 - Lime Rock 100 Miles - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 09 | Porsche 935/77A | 930 890 0021 | GTX | Preston Henn (USA) | Thunderbird Swap Shop (USA) | 11th | 7th | 11th | 59 laps |
17 June 1979 - Brainerd 100 Miles - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 09 | Porsche 935/77A | 930 890 0021 | GTX | Preston Henn (USA) | Thunderbird Swap Shop (USA) | 8th | 8th | 43rd | 32 laps |
7 July 1979 - Watkins Glen 6 Hours - World Championship for Makes
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 09 | Porsche 935/77A | 930 890 0021 | Gr.5 | Rick Mears (USA)/Preston Henn (USA)/Peter Gregg (USA) | Bayside Disposal Racing (USA) | 42nd | 5th | 7 laps - Fire |
15 July 1979 - Mid-Ohio 250 Miles - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 09 | Porsche 935/77A | 930 890 0021 | GTX | Preston Henn (USA)/John O'Steen (USA) | Michelob Light (USA) | 37th | 10th | 18th | 28 laps - DNF |
5 August 1979 - Trans-Am Watkins Glen - Trans-Am
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 09 | Porsche 935/77A | 930 890 0021 | TA-II | Preston Henn (USA) | Michelob (USA) | 11th | 6th | 5th | 27 laps |
23 September 1979 - Road Atlanta 100 Miles - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 09 | Porsche 935/77A | 930 890 0021 | GTX | Preston Henn (USA) | Michelob Light (USA) | 11th | 11th | 16th | 38 laps |
25 November 1979 - Daytona Finale 250 Miles - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 09 | Porsche 935/77A | 930 890 0021 | GTX | Preston Henn (USA) | 5th | 5th | 8th | 47 laps |