Nissan R90C

The R90CK would appear as an evolution of the R89C's design, borrowing many stylistic elements which had been used before. The front end of the car was low, with two deep channels on either side of a slanted nose leading to radiator inlets on the sides of the cockpit. Small slated inlets would also be placed on the leading edge of the car, partially feeding brake cooling ducts. The cockpit would feature a longer raked windshield than the R89C, yet the areas around the cockpit would remain nearly identical, including the sides of the car. At the rear, the rear wing would be mounted high on exposed struts for better downforce.

The design and development of NPTI's R90CK was conducted in association with Ray Mallock Limited and the cars were prepared and run out of RML's workshop in 1990, before being shipped to the United States to take part in the 1991 24 Hours of Daytona.

The R90CP ("P" referring to the Oppama Nissan plant where Nismo is based[1]) on the other hand appeared to favor a low downforce design. The front of the car would feature a higher nose, with the narrow channels eliminated and replaced with large ducts on the inside of the fender. The fenders themselves were also redesigned, with headlights placed vertically instead of the horizontal design on the R89C and R90CK. The cockpit of the R90CK was identical to its R90CP sibling, yet the sides of the bodywork would be changed. Most notably, the rear-view mirrors were integrated into the bodywork on the fender, instead of small exposed mirrors on the side of the windshield. The rear fender would also be different in that the turbo inlet would be placed on the front edge of the fender, instead of on top of the engine cover on the R90CK. For the rear wing, it would be placed much lower on the car, with the rear wheel fender bodywork extending to connect with the rear wing endplates, similar to a style used on the Nissan GTP ZX-Turbo in North America.

Nova Engineering's unique From-A Racing R91CK.

A Nissan R92CP, one of the cars based on the R90C platform.

For 1991, Nissan officially withdrew from the World Sportscar Championship. However Nismo planned to continue competition in the All Japan Sports Prototype Championship, and decided to upgrade the R90CPs to better compete with Toyota and Mazda. The new cars, known as R91CP and R91VP, would have slight modifications over the previous car. Most notably, the boxy turbo inlets which had been placed on the rear fenders of the R90CP were made into smaller slits, while a large snorkel was added to the top of the engine cover to cool the rear brakes, in place of the previous twin brake ducts. The cars would be further modified for 1992 with an upgraded VRH35Z twin-turbo V8, while the cars were renamed R92CP.

For the R90CKs, Nissan ran them mostly at the 24 Hours of Daytona following their retirement from the World Sportscar Championship at the end of 1990. For the 1992 running of Daytona, the R90CKs would have their VRH35Z engines replaced with smaller 3.0L twin-turbo V8s, although they would not be as successful as the race winning R91CP.

Three other unique R90Cs were cars that were based on existing cars but modified. One R89C was upgraded to become an R90CP, originally used by Nissan in the JSPC before all cars were completed. Nova Engineering purchased chassis #07 from Lola and initiated their own upgrades to the chassis, calling the car a R91CK. The final modified car was an R90CP bought by Team Le Mans and modified into what they termed the R91VP. Both cars featured minor aerodynamic differences from the other R90CKs and R90CPs.

Although the opening round of the 1990 World Sportscar Championship season was held at Suzuka Circuit in Japan, the new R90CKs intended for the series would not be completed in time for the event, leaving the previous Nissan R89Cs to be run by the European team. A lone JSPC R90CP was run by the Japanese team but did not finish. By the second round of the season at Monza, the first three R90CK chassis would be completed with Northern Ireland man Kenny Acheson and Brits Julian Bailey and Mark Blundell joining Italian Gianfranco Brancatelli as the driving line-up. Although both cars ran well, one would not have enough fuel to reach the end of the race. The second team car would however manage to finish, taking seventh place.

Both cars ran towards the top of the field once more at Silverstone before a suspension failure and fuel problems eliminated both cars in the final few laps. The team would finally see some success at Circuit de Spa-Francorchamps though, with both cars finishing and the Acheson and Bailey car taking third place, two minutes behind the winning Mercedes-Benz. The driver line-ups were switched for Dijon, but the new Bailey and Blundell duo once again took a podium.

Although the Nissans would not win podium placings at the Nürburgring, the team managed to bring home both cars in the top ten for the first time. As the season went on, the team continued to improve, with Donington Park seeing both cars finish in the top six, with Acheson and Brancatelli finishing fourth. This success was however aided by the post-race disqualification of both Jaguars that had finished ahead of the Nissans.

At the fly-away round at Montreal, the R90CKs would manage to take their best finish so far that season. The race had to be stopped early due to dangerous conditions, but at the time the Nissan of Bailey and Blundell were running only six seconds behind the leading Mercedes-Benz, earning the team second place when the red flag was shown; the second car took fifth. The good results for the team would continue into the final round of the season at Mexico City with Bailey and Blundell taking second place once again, although this time two laps behind the winning Mercedes-Benz. Acheson and Brancatelli managed fourth place. In the teams championship, Nissan would take third place, a mere four points behind Jaguar. Julian Bailey would be the highest ranking Nissan driver in the driver's championship, finishing the season in ninth place.

Following the 1990 season, Nissan chose to leave the World Sportscar Championship and concentrate on the JSPC and their efforts in the IMSA GT Championship in North America. Nissans would only compete one other time before the World Sportscar Championship was abandoned after 1992, with Nova Engineering's R91CK running in an invitational class at the 1992 1000km of Suzuka, finishing in fourth place.

Differing from the WSC R90CKs, Nissan would use their R90CPs for the All Japan Sports Prototype Championship. Japanese drivers Masahiro Hasemi, Toshio Suzuki, and Kazuyoshi Hoshino would join Swede Anders Olofsson as the factory drivers. The cars debuted at the 500 km of Fuji and were immediately on pace, taking the second and fourth spots behind Toyota's also new 90C-V.

Following the cancellation of the second round at Fuji, a third race was later held, and Nissan was able to score their first win. Hasemi and Olofsson drove their car to a two lap victory over a Porsche 962C, while the second car finished off the podium. Hoshino and Suzuki then took the next race win at the 1000km Suzuka, followed by Hasemi and Olofsson taking their second victory at Sugo. The final race of the JSPC season, once again at Fuji, would however break the Nissan's three race streak, with Toyota taking victory by just over a minute. The three race wins would be enough in the end to allow Nissan to win the manufacturer's championship, with all four Nissan drivers tying for the drivers championship.

The JSPC From-A Racing R91CK during an exhibition at the 2006 Goodwood Festival of Speed.

For the 1991 season, Nissan upgraded their cars into the R91CPs, while some older cars were sold off to privateers. Nova Engineering upgraded their R90C to R91CK specification utilizing the Yatabe (Japan Automobile Research Institute—JARI) wind tunnel, while Team Le Mans bought an R90CP and modified it into their own R91VP. Keeping the same driver line-up as the previous season, the factory Nissan team proved the pace of the new R91CP by winning the opening round at Fuji, while the Nova Engineering entry took second, and Team Le Mans fourth. The second race at Fuji saw Nissan's main rival, Toyota, debut their new 91C-V, yet it would not be capable of fighting the R91CPs. Nissan took the top two positions with their factory cars, a lap ahead of the new 91C-V.

By the third race at Fuji however, Toyota was able to improve their new car and take their first overall victory of the season, leaving Nissan to settle for second place, ten seconds behind, while the second team car was taken out in an accident. The 1000 km Suzuka saw further problems for the team as the Nova Engineering entry actually took second place ahead of the factory entry in third, several laps behind. A similar event occurred at the next round, with Nova Engineering ahead of Nissan, yet all cars managed to finish on the same lap as the winning Toyota.

Nissan managed to overcome Toyota at the 1000 km Fuji, winning by a minute even though the other three Nissans in the field were unable to finish. However, newcomer Jaguar would manage to take victory at the final race of the year, leaving Toyota in second and Nissans in third and fourth, several laps behind the dominant Group C car. Even with its troubles, Nissan was able to overcome Toyota in the points championship, winning by three points. Kazuyoshi Hoshino and Toshio Suzuki won the drivers championship by a mere two points over Toyota's leading pair.

A R92CP with its VRH35Z engine shown at Nismo Festival in 2006.

In what would become the final season of JSPC, Nissan would once again upgrade their cars into the R92CP. Nova Engineering retained their R91CK, while Team Le Mans would leave the series. Team Take One would take up their place with a former factory R91CP. For the 1992 season, the championship was actually divided into two classes, with the older Nissans running in C1, while cars which conformed with the 1992 World Sportscar Championship 3.5L engine specifications would run in C. This meant that although Nissan would be competing against newer and faster cars, they would still be able to compete for victories against competitors in their class.

At the opening round at Suzuka, no C class cars would compete, leaving Nissan open to take the race victory in the R92CP's debut, with Jeff Krosnoff and Masahiko Kageyama replacing Anders Olofsson on the winning car's driver line-up. Nova's R91CK took second, ahead of a trio of new Toyota 92C-Vs. At the next round, the 1000 km Fuji, Mazda's Mazda MXR-01 C class car would show, yet suffer reliability problems. Problems for Toyota as well allowed Nissan to take the top four spots.

The next race at Fuji would once again go to Nissan, as Hoshino and Suzuki would beat the fastest Toyota by over a minute. This would be repeated at Sugo, although Nissan would manage to take that victory by a mere three seconds. However, Toyota would bring their C class competitor, the TS010 to the second 1000 km Fuji, and easily take the win over the second place R92CP. A second TS010 would join at the final round at Mine, but Nissan chose to bring their C class competitor to the event as well, the NP35. Even with five Nissans, they would not be able to overcome the Toyota challenge, as the TS010 once again took the win, leaving Nissans in second and third. Even with losing the final two rounds, Nissan was able to take the championship in their class, even though Toyota won the separate C class. Kazuyoshi Hoshino would take the solo drivers championship.

One of the R90CKs used by NPTI at the 24 Hours of Le Mans.

Beyond the World Sportscar Championship and All Japan Sports Prototype Championship, Nissan's R90Cs have competed in various other events around the world. Most notably, at the 1990 24 Hours of Le Mans, where four R90CKs and one R90CP were joined by two older privateer R89Cs for an attempt at winning the race overall. The JSPC Nissan Motorsport team would run a lone R90CP, while the WSC Nissan Motorsports team would run their two new R90CKs. The American Nissan Performance Technology Inc. (NPTI) from the IMSA GT Championship team would also run two R90CKs. Courage Compétition and Team Le Mans would both run their older R89Cs. However the race would take its toll on the Nissans, and only three would finish. The lone R90CP of Masahiro Hasemi, Kazuyoshi Hoshino, and Toshio Suzuki would finish in fifth place, 11 laps behind the winning Jaguar. The American R90CK would take 17th place, while Courage's older R89C would finish 22nd.

The R90CK was notable for achieving the highest straightline speed on the Mulsanne Straight at the Le Mans circuit following the installation of a sequence of tight serpentine curves (chicanes). Mark Blundell reached at 366 km/h (226.9 mph) on his pole position lap - 24.2 mph less than the previous record trap speed without the chicanes in place.[2] The qualifying engine, normally capable of up to 1000 bhp, had a mechanical issues leading to the wastegate being jammed, leading to an engine which produced well over 1100 bhp.[3][4] Bob Earl took the fastest lap during the race in the NPTI car at 3:40.030[5] This trap speed record with the chicanes in place still stands to this day. Even with this performance, Nissan would not return to Le Mans with their prototypes following their departure from the World Sportscar Championship at the end of 1990, until their front-wheel drive effort in 2015.

Nissan would also have a notable presence at the 24 Hours of Daytona. Although part of the IMSA GT Championship which was usually contested by Nissan's GTP ZX-Turbo, it was decided that the R90Cs were better suited for the Daytona endurance. Three R90CKs were entered in 1991 by NPTI under an invitational class for Group C cars. Although two failed to finish, the R90CK of Bob Earl, Derek Daly, Chip Robinson, and Geoff Brabham managed to finish first in class and in second place overall, although 18 laps behind the winning Joest Racing Porsche 962C.

Nissan would return in 1992, although with even more cars. Two R90CKs were modified with motors that allowed them to run the IMSA GTP class. The factory team also brought an R91CP from Japan, which would compete in the invitiational class. Privateer Nova Engineering Racing ("From-A" livery) would also come from Japan with their R91CK, also in the invitiational class. While the R90CKs suffered, the R91CP would manage to take the victory, nine laps ahead of a Jaguar. Nova Engineering would also manage to take eighth place.

Nissan would make their final appearance with sports cars at the 1993 1000km Suzuka, contested in part by the new All Japan GT Championship (JGTC) which had replaced the JSPC. Team Le Mans would enter a former factory R92CP, while Nova Engineering would run their R91CK. With a Spice-Acura as the only other prototype competitor, the two cars would easily take victory, with Team Le Mans ahead of Nova Engineering.