PORSCHE RACING HISTORY1981 - Riverside 6 Hours
26 April 1981 - Riverside International Raceway, USA
John Fitzpatrick & Jim Busby win in a Porsche 935 K3/80
Overall - 1st, 2nd, 3rd - GTX - 1st, 2nd, 3rd
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 1 | Porsche 935 K3/80 | 000 00011 | GTX | John Fitzpatrick (GB)/Jim Busby (USA) | John Fitzpatrick Racing (GB) | 1st | 1st | 2nd | 199 laps |
| 8 | Porsche 935 JLP-3 | JLP-3 | GTX | John Paul Sr. (USA)/John Paul, Jr. (USA) | JLP Racing (USA) | 2nd | 2nd | 1st | 199 laps |
| 9 | Porsche 935 K3 | 009 00030 | GTX | Bobby Rahal (USA)/Brian Redman (GB) | Cooke-Woods Racing (USA) | 3rd | 3rd | 4th | 197 laps |
| 90 | Porsche 935 K3 | 930 770 0911 | GTX | Bob Garretson (USA)/Ralph Kent-Cooke (USA)/Roy Woods (USA) | Bob Garretson Enterprises (USA) | 4th | 4th | 13th | 190 laps |
| 86 | Porsche 935/80 | 000 00024 | GTX | Hurley Haywood (USA)/Bruce Leven (USA) | Bayside Disposal Racing (USA) | 5th | 5th | 7th | 189 laps |
| 18 | Porsche 935 JLP-2 | 009 00043 | GTX | Carlos Moran (ES)/Karen Erstad (USA) | JLP Racing (USA) | 10th | 8th | 22nd | 178 laps |
| 30 | Porsche 935/81 | JR-001 | GTX | Gianpiero Moretti (I)/Jochen Mass (B) | Momo/Penthouse (I) | 14th | 9th | 5th | 172 laps |
| 51 | Porsche 911 Carrera RSR | 911 360 0601 | GTO | Robert Kirby (USA)/John Hotchkis (USA) | Casa Blanca Fan | 16th | 5th | 37th | 168 laps |
| 56 | Porsche 911 Carrera | 911 210 0224 | GTO | Rick Borlase (USA)/Michael Hammond (USA) | Rick Borlase | 17th | 6th | 39th | 168 laps |
| 43 | Porsche 911 Carrera | GTO | Bob Gregg (USA)/Len Jones (USA) | Bob Gregg | 20th | 7th | 38th | 162 laps - DNF | |
| 62 | Porsche 911 SC | GTU | Bill Koll (USA)/Jeff Kline (USA) | Kegel Enterprises (USA) | 22nd | 6th | 29th | 158 laps | |
| 46 | Porsche 935 J | 000 00012 | GTX | Mauricio DeNarváez (COL)/Bob Akin (USA)/Skeeter McKitterick (USA) | Mauricio DeNarvaez (CO) | 23rd | 10th | 9th | 154 laps |
| 26 | Porsche 911 Carrera | GTO | Sergio Nardi (USA)/Angel Nardi (USA)/Steve Michaelson (USA) | Nardi Motors | 24th | 8th | 55th | 154 laps | |
| 04 | Porsche 911 Carrera RSR | 911 560 9119 | GTO | Tico Almeida (USA)/Rene Rodriguez (USA) | T & R Racing (USA) | 26th | 10th | 36th | 151 laps |
| 57 | Porsche 914/6 | GTU | Robert Overby (USA)/Jeff Scott (USA)/Wayne Baker (USA) | Personalized Autohaus (USA) | 28th | 7th | 64th | 145 laps | |
| 45 | Porsche 914/6 | 914 043 0593 | GTU | Bill Cooper (USA)/Dwight Mitchell (USA)/Ray Ratcliff (USA) | Autosport Technology (USA) | 29th | 8th | 30th | 132 laps |
| 31 | Porsche 911 Carrera RSR | 911 460 9048 | GTO | Tom Alan Marx (USA)/Dennis Lanfre (USA)/Bill Follmer (USA) | RSR Associates (USA) | 30th | 12th | 59th | 129 laps |
| 3 | Porsche 935 M16 | 930 890 0013 | GTX | Rolf Stommelen (D)/Howard Meister (USA) | Andial Meister Racing (USA) | 31st | 11th | 3rd | 125 laps - DNF |
| 17 | Porsche 911 | GTU | Richard Woodbury (USA)/Bruce Campbell (USA) | Richard Woodbury | 32nd | 9th | 50th | 110 laps | |
| 22 | Porsche 914/4 | GTU | Wayne Baker (USA)/Robert Overby (USA) | Personalized Autohaus (USA) | 34th | 10th | 34th | 98 laps - DNF | |
| 84 | Porsche 935 M16 | 930 670 0171 | GTX | " Jamsal" (ES)/Eduardo Barrientos (ES) | Scorpio Racing (ES) | 35th | 12th | 20th | 87 laps - DNF |
| 73 | Porsche 911 | GTU | Jerry Demele (USA)/Terry Herman (USA) | Douglas Dowden (USA) | 43rd | 15th | 43rd | 53 laps - DNF | |
| 0 | Porsche 935 K3/80 | 000 00010 | GTX | Ted Field (USA)/Danny Ongais (USA) | Interscope Racing (USA) | 44th | 15th | 8th | 48 laps - DNF |
| 08 | Porsche 935 K3 | 000 0009 | GTX | Preston Henn (USA)/Marty Hinze (USA)/Gary Belcher (USA) | Preston Henn (USA) | 45th | 16th | 40th | 33 laps - DNF |
| 24 | Porsche 911 | GTU | Zvonimir Jovanovic (USA)/Carl Wong (USA) | Zvonimir Jovanovic | 46th | 16th | 54th | 33 laps - DNF | |
| 21 | Porsche 935 Turbo | GTX | Jamey Mazzotta (USA)/Steve Earle (USA) | KMS Research | 47th | 17th | 16th | 32 laps - DNF | |
| 58 | Porsche 911 Carrera RSR | 911 560 9121 | GTO | Alan Johnson (2) (USA)/Chuck Kendall (USA) | Kendall Racing (USA) | 48th | 15th | 25th | 30 laps - DNF |
| 39 | Porsche 911 | GTU | Greg LaCava (USA)/Claudia LaCava (USA) | Fatcola (USA) | 55th | 18th | 47th | 17 laps - DNF | |
| 42 | Porsche 911 Carrera RSR | 12803002 | GTX | Bob Copeman (USA)/Lawrence Farmer (USA)/Ken Moore (USA) | Alex Porsche Haus (USA) | 57th | 19th | 52nd | 7 laps - DNF |
| 09 | Porsche 935 K3 | 930 890 0021 | GTX | Gary Belcher (USA)/Preston Henn (USA)/Marty Hinze (USA) | Preston Henn (USA) | 58th | 20th | 15th | 5 laps - DNF |
World Championship for Drivers and Makes IMSA - International Motor Sport Association
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