Nothing Came Close: The Group A BNR32
|Calsonic Group A R32 GT-R at the NY Auto Show|
This story was written by Alexander Gorodji about six years ago, before he passed away. I had him do some research and writing for me, when he was having a bit of a rough time in his life. He was a big R33 guy, so I had him write about R32’s.
|Alexander with the left hand drive R34 he made.|
Surprisingly this story started a long time before the Nissan Skyline BNR32 was launched.
It was 1964… Dr Shinichiro Sakurai – Chief Development Engineer of the Prince Motor Company had built his second racing car – The Skyline GT (S54-I). The car had 2-liter, 6-cylinder G7 engine with output 105 PS.
The car took second place in the second Japanese Grand Prix in May 1964. It lost just to the Porsche Carrera 904, but led the race for one (the 7th) lap.
Dr Sakurai regarded the defeat from Porsche as a personal challenge, and had chosen his weapon – a prototype-class car – the Prince R380. He had his revenge; the R380 dominated the third Japanese Grand Prix. It had the GR8 – the grand-grandfather of the GT-R’s legendary RB26DETT engine.
However, the GR8 had its own ancestor – the mentioned above G7. Both engines had six cylinders in-line, but the G7 had a square bore and stroke configuration (75mm x 75mm) with a displacement of 1988cc, whereas the GR8 had a bore/stroke of 82mm x 63mm respectively, and a displacement of 1996cc. The GR8 also had a higher compression ratio (11:1). The reduction in stroke did not allow the GR8 to produce significantly more torque than the G7 – the GR8 produced 17.5kg/m of torque at 6400rpm, and the G7 17.0kg/m at 4400rpm – but it did produce more horsepower (197ps at 8400rpm). The higher rev rate was made possible by the use of seven crankshaft bearings, instead of the G7’s four. Triple Weber carburetors supplied the GR8 with air/fuel, and the engine featured a 13-liter dry sump lubrication system. The main difference between the GR8 and its predecessor was the GR8’s dual-overhead camshaft with four valves per cylinder.
The next generation of this family of engines was born in 1968 for the first GT-R – the Nissan Skyline GT-R (PGC 10). It was fitted with the S20 – a production version of the GR8, which can be considered as the grandfather of the RB26DETT. The first comparability is the engine block, which was canted to the left side of the engine bay.
The S20 is a detuned racing GR8. That’s all you can usually read about the S20. Yes, the S20 had smaller displacement (1989cc as opposed to1996cc) and a lower compression ratio (9.5:1 as opposed to 11:1). The S20 produced a little bit more torque than the GR8 (18.0kg/m@5600rpm), but less horsepower because of a limitation in the max rpm (160ps@7000rpm) and a change to the torque curve.
However, the S20 was not simply the de-tuned GR8; it was a new engine for a production car which could be used for touring car racing. There were many significant differences between these engines. For example, the GR8 used camshaft gears and the S20 a timing chain; the GR8 had a magnesium oil pan and rocker cover, the S20 items were aluminum. Engine reliability was improved by using aluminum alloy pistons and special alloy conrods and crankshaft. Five of the seven crankshaft bearing caps were fixed by the side bolts; a reinforcement technique typically used on racing engines.
Instead of Weber carburetors, the S20 was equipped with three Mikuni twin-choke Solex N40PHH carburetors. Solex N44PHHs and Weber 45DCOEs were available as options, though.
The S20 had an electronic, 6-transistor ignition system – the innovative feature introduced at the end of the 1960s. You can see something that looks like a distributor on the engine, but, in fact, it’s the trigger wheel of the electronic system.
The S20 produced 160 PS and 18 kg/m of torque – very impressive figures for the automotive industry at the end of 60s.
Thanks mostly to this engine, the PGC10 became one of the fastest production cars in the world, and dominated on the racing scene. It won a total of 58 races; 49 consecutive, that makes this car one of the most glorious machines in history of the world auto racing.
|RB20DET not in an R31|
The next page of this story is about the Nissan Skyline R31, which was launched in August 1985. This machine is interesting for us because of two main features: the RB20DET engine and the HICAS (the High-Capacity Actively Controlled Suspension) – the Nissan’s version of a rear-wheel or all-wheel steering.
The RB20DET – the father of the RB26DETT was a dual overhead cam, single ceramic – turbo engine, which produced 210 PS.
The HICAS turned the R31’s semi-trailing arms in the same direction as front wheels by 05o to increase stability during high-speed cornering and fast lane changing. The system was activated from 19 mph.
The ’87 version of the HICAS added ‘the delay control,’ which postponed the rear-wheel turn to avoid understeer, and to allow the car’s rear end to slide. Different modifications of the HICAS remained standard on all Skyline models.
The R31 GTS-R entered Group A of the Japanese Touring Car Championship in 1987. The Reebok R31 GTS-R piloted by Masahiro Hasemi and Anders Olofsson won the Driver’s Championship title in the JTC class 1 in 1989. The Nissan was second after the Ford Sierra in Division 1. However, the R30 and the R31 were ever dominant on the racing scene. In general, the BMW 635si and, mostly, the Ford Sierra RS500 were more successful in Group A before 1990. Nissan had to do something to get back the racing glory of the C10 GT-R.In the second half of the 1980s Nissan was losing money and was not successful in any respect. But, the company didn’t lose spirit, though, and planned to become the number one auto manufacturer in Japan in the 1990s, through a project called ‘901.’
In 1985, Naganori Ito succeeded Dr. Sakurai and became responsible for a new generation of Nissan sports cars. The R31 wasn’t very popular because of its poor performance and modest success in racing, and Ito-san realized that Nissan needed a car that would revolutionize touring car racing and the public’s perception of Nissan’s brand image. Nissan needed something similar to the C10 GT-R which became a legend thanks to its unparalleled 50 wins within three years. Ito-san understood that Nissan needed a new GT-R, but decided not to disclose his idea except to a few company executives; the responsibility was too great. The development project was codenamed ‘GT-X,’ and work started in May 1986.
|Hiroyoshi Kato participating in N1 racing in 1990|
An extremely valuable member of the GT-X team was Chief Test Driver Hiroyoshi Kato. It is to his credit that the GT-R has its unique handling. Ito-san used to say to his engineers: “Listen to the test drivers as to the voices of the Gods.” Kato-san put a tremendous amount of hard work into developing the GT-R. In many ways the true birthplace of the new GT-R was the legendary Nordschleife of the Nurburgring. When testing began the BNR32’s behavior was unpredictable; sometimes understeer would suddenly be replaced by oversteer, and vice versa- the ABS system suddenly started to ‘panic’ under lateral G-load.. A high level of stability was finally achieved, but understeer – caused by a number of factors – remained. The chief factor was the unfavorable weight distribution: 59.4 front, 40.6 rear, due to the engine overhanging the front axle, and despite the fuel tank being located behind the rear axle. Together these induced a high moment of polar inertia.
Nissan’s engineers tried their best to decrease the weight of the car. The hood and front fenders were aluminum (resin washers had to be placed on the front fender bolts because aluminum and steel parts in contact generate electric corrosion). However, with its curb weight of 1430kg, the BNR32 was not the lightest among the production sports cars.
Besides the excessive weight (and its poor distribution), the new GT-R also had other imperfections: body rigidity wasn’t high; the suspension bushings weren’t hard enough; the aerodynamics wasn’t perfect; the car had a high drag coefficient (0.40); the large aperture in the nose of the car and the underbody generated a lot of drag; and the front bumper narrowed at its lower part exposing part of the wide front tires to the oncoming airflow. Additionally, the slope of the rear window was too steep, also generating drag. The airflow mostly remained attached to the rear window and both surfaces of the rear wing, resulting in a rather high downforce (Cl -0.15). However, the front coefficient of lift was +0.20, so the aerodynamic balance of the car generated understeer upon exiting corners when the throttle was applied and the front wheels became unloaded.
|R32 GT-R at Nurburgring|
Kato-san became more and more frustrated by the car’s understeer. Excessive stability of a new car did not allow him to get the car around the Nurburgring corners at higher speeds; he just couldn’t apply enough throttle. Too much stability generated a lot of understeer. Less stability would provide more oversteer, which would help to turn the nose of the car towards the corner exit. This paradigm – stability contradicts oversteer – really determines how controllable a car is, and how fast it is in corners. To be fast, a car should be stable – stability brings control and a high level of traction without a loss of power and speed. On the another hand, if a car is too stable, it doesn’t generate a yaw moment, and therefore understeers, which requires reduction of the throttle, whereas an oversteering car can be accelerated (which is what a skillful driver does to bring more load onto the rear wheels to increase traction).
At the end of his first trip to the Nurburgring Kato-san managed to set a Nordschleife lap time of 8min 30sec. He recalls that before the next trip to the Nurburgring the car’s stability had to be reduced before any further progress as regards lap times could be made. The GT-X team did its homework and, at the Tsukuba circuit the car produced a lap time of 1min 8sec, and then, finally, during the next trip to the Nurburgring, a lap time of 8min 20sec was achieved. The Nissan team’s goal was to beat the production car record at the Nordschleife, which was held by the Porsche 944 (8min 45sec); the Nissan was over 20 seconds faster! However, the main problem remained: the R32 GT-R was an understeering car, particularly at high speed corners and on the turning-in stage of cornering.
|R32 GT-R front suspension links. This is Nismo R-Tune coil overs.|
The new Nissan sports car multi-link suspension was born from the ‘901’ project. The new suspension replaced the front MacPherson and rear semitrailing suspension as used on the R31. The new multi-link rear suspension was installed in an S13 Silvia in 1988, and then it debuted in the R32 Skylines. The R32’s rear suspension had two upper links with two attachment points to the axle housing. The lower A-arm was attached to the subframe at an angle similar to that of a semi-trailing arm. The lower arm geometry and compression of the bushings at the attachment points under lateral force, acceleration or deceleration made the rear tire toe-in a little during acceleration or braking to prevent uncontrollable oversteer, and stabilized the car’s rear end.
|Rear upper link for R32 GT-R|
Furthermore, the lower A-arm was slanted, thus forming, together with the upper links, a rear suspension setup with anti-squat geometry. This provided rapid transmission to oversteer in corners when the power was applied hard. The lateral link, located behind the lower arm connected to the Super HICAS, combined with the lower arm and upper links to provide precise toe control.
|Front suspension components for an R32 from FAST|
The front suspension was developed under the leadership of Nissan’s chassis specialist Takaaki Uno. It was considered by some to be revolutionary. This multi-link suspension was, basically, a double-wishbone design with a changed upper wishbone. The I-shaped upper link was attached to the strut housing at a point higher than the tire’s radius. It was connected to the shock absorber and the axle housing via a third link. The third link took away the restriction of the upper link movement and maintained maximum tire traction. Without the third link the camber would change when the tire moved on bumps, thus losing grip. Also, the different length and angle of the upper arm and lower links adjusted the camber changes relative to the suspension travel. The third link also allowed the optimum kingpin axis angle, providing the best possible steering axis. When the body rolled during cornering, the front multi-link suspension kept the front tires perpendicular to the ground, thus reducing the camber changes and improving front tire grip. The axle housings were made from aluminum to reduce the unsprung weight. The hub bearings in the axle housings, however, frequently broke. A twisted upper link moved the instant center forward, increasing the anti-lift angle. The castor angle, castor trail and scrub radius were balanced, improving handling and steering feel.
The multi-link setup also improved shock absorber control: the shock absorbers moved by exactly the same amount as the wheels. The BNR32’s shock absorbers had two types of valve, for low and high shaft velocity respectively. The front shock absorbers had 178kg (0.3m/sec) rebound and 51kg bump (0.3m/sec). The rear 113kg (0.3m/sec) rebound and 41kg (0.3m/sec) bump.
Nissan’s suspension engineers tried to neutralize the GT-R’s understeer by changing the suspension setup. The result was the only oversteering suspension setup among all production cars in the world. Usually manufacturers tune suspension in such a way that it provokes understeer as an active safety feature. For this purpose they install a front anti-roll bar which is thicker than the one at the rear, and front springs that are stiffer than those at the rear. This is exactly the opposite suspension setup to that found in the BNR32. The diameter of the front anti-roll bar was smaller than that at the rear – front 20mm, rear 25.4mm – and the front spring rate was 2.4kg/mm, whereas the rear was 2.7kg/mm.
The new generation of HICAS, Super HICAS, was installed on the BNR32. It was an electro-hydraulic system, like the previous generation, but there were a couple of main differences between the two generations. The Super HICAS actuator – an hydraulic cylinder – was placed between the lateral links of the rear suspension, and controlled them like a steering rack. Whereas the previous generation of HICAS could turn the rear wheels in the same phase (direction) as the front ones, the Super HICAS was able to turn the rear wheels in the opposite direction!
At low and medium speeds into slow corners the rear wheels counter-steered by 1 degree to help the car turn in. After that the wheels turned to match the same direction as the front wheels – by less than 1 degree – to provide stable cornering and to damp the yaw moment.At the same speeds in fast corners the rear wheels did not turn during the entrance to the corner, and then turned to within 1 degree of the same direction as the front wheels, as in slow corners.At higher speeds the rear wheels did not turn in the entrance to the corner but then turned – by 1 degree – in the same direction as the front wheels.
The Super HICAS electronic control unit received signals from the steering angle and vehicle speed sensors. The lateral G- sensor input was excluded from the system. The steering was speed-sensitive. The solenoid valve regulated the power steering fluid pressure in the power steering rack.
The GT-R was equipped with the RB26DETT twin-turbo engine. For Ito-san the main goal of the future car was winning Group A of the Japanese Touring Car Championship (JTCC), and choosing the engine was devoted exclusively to this goal. Initially, a 2.4-liter twin-turbo engine was considered, but after the electro-hydraulic all-wheel drive system was installed, the engineering team discovered that the car was approximately 100kg heavier, so they decided to increase the displacement to 2.6 liters. This then, according to the rules, placed the car (by multiplying the displacement of a turbo engine by 1.7) into the category of 4-4.5-liter naturally-aspirated engines; the minimum weight for which was 1260kg. Further increasing the displacement to 2.8 liters, which, incidentally, is currently a very popular upgrade for the RB26DETT, would place it into the 4.5-5-liter category, which had a minimum weight of 1340kg. Thus, increasing the displacement to 2.8 liters would have required further increasing the minimum weight by 80kg; a very significant weight increment for a racing car.
In the end the GT-X team decided to stay with the 2.6-liter displacement, certain that this would yield enough power. These days, though, with many years’ experience of tuning the RB26DETT, we know that even a minor increase in the displacement provides a significant power improvement. Of course, the creators of the GT-R didn’t have this experience, but, more importantly, another consideration motivated the GT-X team: race car dynamics is not just determined by power-to-weight ratio – the increase in displacement would not have been worth the extra 80kg. History shows that this engine displacement choice was perfect for the Group A series, but it brought with it certain limitations the GT-R in other categories of racing. It’s interesting to notice that the GT-R’s closest rival among production cars– the Toyota Supra – had the 3-liter 2JZ-GTE engine, because the engine choice was not limited by racing regulations.
|This is a later “N1” block. As noted by the 24U embossed in the side of the block. A standard block is a 05U|
Despite the above mentioned displacement limitation, the RB26DETT proved to be one of the most successful engines in the history of the world’s auto industry. It happened to be one of the most tunable engines. This is one of the main reasons for its popularity. Its six in-line cylinder configuration makes this engine very balanced and smooth. This factor, as well as its ‘oversquare’ configuration, with an 86mm bore and a 73.7mm stroke, allowed up to 8000rpm or, with upgraded and balanced internal parts, 10,000rpm or more. The stock/street version of the R32 GT-R had two small Garrett TE2701 turbines to reduce the turbo lag (compressor: housing T3, A/R 0.42, compressor wheel T3, trim 50T; turbine: housing T25, A/R 0.48, turbine wheel T25, trim 62T). To make the lag even shorter, the exhaust turbines were ceramic, meaning they were lighter and spooled up faster than steel ones. These turbines provided maximum boost of 0.78kg-cm2. Compression ratio was 8.5:1.
|Factory intercooler and piping on a Nissan Skyline GT-R|
The car was equipped with a big intercooler, a large plenum chamber, and six individual throttle valves. This air induction system, typical of racing engines, improved the throttle response. The engine control unit (ECU) sent signals to the power transistor that powered the six individual ignition coils on the sparkplugs. This feature was important for the high boosted turbo engines. In the same way, the six fuel injectors were directly controlled by the ECU, so both systems were tunable electronically. The stock engine output was 36.0kg/m of torque @4400rpm, but power was officially limited to 280ps in accordance with the (absurd) agreement amongst Japanese manufacturers not to exceed this limit. In reality, engine output was around 300ps. The planned power of the Group A racing version of the engine had to be up to 600-650ps.
Superintendent of the project Naganori Ito and his team of engineers guessed that with such power output the car could have traction problems. Also, they were under the influence of the Porsche 959, with its electronically-controlled, variable torque split all-wheel drive system.
One of the members of the Project GT-X engineering team was Kozo Watanabe – Chief of the Vehicle Experimental Department. He recalls that all the mechanical devices for the electro-hydraulic system – the ABS system and the multiplate wet torque transfer clutch – had been in development since 1984, but the engineers experience severe durability problems with these devices and systems. The multiplate clutch often overheated and broke. Many ‘Project GT-X’ engineers insisted on adapting a viscous clutch all-wheel drive system, similar to that used on the Nissan MID-prototype car.
Actually, the AWD system with the Ferguson viscous clutch had been considered for installation on the R31, but was delayed for the R32 series. Watanabe-san once said that he and his supporters realized that a viscous clutch system is not a sufficiently precise tool for controlling the car’s dynamics. It’s slower, and sometimes doesn’t let the driver control the car as he wants. Ito-san, using his authority as project superintendent insisted that development of the multiplate transfer clutch would continue at least for one year. If the engineers failed to achieve a decent level of durability, the GT-X would be a rear-wheel drive car – we’re all very lucky that they succeeded.
Nissan’s part-time, all-wheel drive system – ATTESA E-TS (Advanced Total Fraction Engineering System for All-Electronic Torque split) – was based on a different principle than Porsche’s 959 system. Both AWD systems utilized wet multi-plate electro-hydraulic clutches to transfer up to 50 per cent of the torque to the front wheels. However, as was mentioned above, while the Porsche’s system was programmed to split the torque according to the car’s static and dynamic weight distribution, the ATTESA E-TS remained in rear-wheel drive mode until the rear wheels lost traction. It was the main concept of the system, as it was presented to the public.
All this, though, is an unforgivable simplification of the ATTESA system. First of all, it transferred torque to the front wheels in certain driving situations even if wheel spin did not occur. Also, the system kept the rear-wheel drive mode during cornering before the corner exit, thus the lateral grip of the GT-R’s front tires was not jeopardized; Nissan engineers called it the ‘lateral G- control.’ Because the Porsche’s AWD system always transferred at least 20 per cent of the torque to the front wheels, Nissan’s engineers saw that the Porsche 959’s front-wheel lateral grip decreased under the application of torque (as well as because of the lack of vertical load on the front wheels during the corner exit because of the rear weight bias). This is why the 959 was not the ultimate-handling car; it understeered.
The ATTESA E-TS electronic control unit received signals from four wheel-speed sensors, three G-force sensors (two longitudinal and one lateral), the ABS control unit, and the engine control unit (rpm and throttle position). The ATTESA E-TS control unit sent its signal to the hydraulic unit, which generated variable oil pressure applied to the transfer unit (wet multiplate clutch) actuator.
The transfer unit was attached to a 5-speed gearbox which was almost identical to that of the Z32 (300ZX Turbo). However, because of the high traction of the ATTESA system, the load to the GT-R gearbox was much higher than to that of the rear-wheel drive Z32. Therefore, wider and stronger aftermarket gear teeth were required. Also, the synchros weren’t strong enough (again, aftermarket items were available). Finally, once the reliability problems of the multiplate transfer clutch were fixed, it proved to be very durable and trouble-free.
Engine torque was transmitted through the push-type power clutch, and a portion was distributed by the multiplate wet clutch to the front wheels through the front open differential (F160), which was used on all subsequent GT-R models (with a different final ratio for the R34). The front differential was another weak part of the GT-R’s drivetrain; if you make drop-clutch starts, expect to fine it broken. The main portion of the torque was distributed to the rear wheels via a plate-clutch- type limited-slip differential (R200). A torque meter located on the dash received signals from the ATTESA E-TS control unit, and allowed the driver to see how much torque was being sent to the front wheels at any given time.
Nissan’s engineers developed a new approach to integrating all-wheel drive (AWD) systems with anti-lock brake systems (ABS). When a purely mechanical (non-intelligent) AWD device senses that a wheel (or wheels) has locked (front or rear), it locks the wheel(s) at the other end of the car. The approach to integrating an all-wheel drive system with ABS found in other all-wheel drive cars during the 1980s and 1990s was to disconnect the all-wheel drive when the ABS was activated. Nissan’s engineers, however, solved the problem in the opposite way. The ATTESA E-TS was integrated with the ABS control in a single module and worked as a good ensemble: to prevent locking the wheels Nissan engineers used a front/rear torque split; there’s less probability of a wheel locking if torque is applied to it. So-called ‘engine braking,’ familiar to most drivers, is more efficient than braking by just using the brakes.The ATTESA E-TS sent some torque to the front wheels during sudden braking. As a result, ABS performance was improved and braking became well balanced. The ABS had just three channels, although the GT-R braking was efficient, the car was stable, and the stopping distance was short.
Finally, the new GT-R – The Skyline R32 (BNR32) was introduced to the public in August 1989.
The car received very good press. All journalists and test drivers noticed its amazing traction and astonishing corner exit speed. Actually, the BNR32 was the first GT-R to come with an explicit philosophy by Kazutoshi Mizuno years later: “A supercar for anyone, anywhere, any time.” I must recall here a remarkable story from Car magazine regarding the R32 test at the Nurburgring at the beginning of the 1990s. A team from the magazine, together with a group of Japanese journalists – which, combined, contained no professional drivers and no-one with much familiarity with the Nordschleife – was faster in the BNR32 around this circuit on the day than German professional race drivers in the Porsche 928GT, Mercedes 500SL and BMW M5.
It’s important to note that this high performance was delivered in a very entertaining, driver-involving fashion. The ATTESA active torque distribution system didn’t spoil the ‘natural’ feel of a good sports car. The car felt more like a rear-wheel drive car with incredibly high traction. However, there was a trick to driving the car, which distinguished it from any rear-wheel drive car: when the car power oversteered, or even drifted around a corner, the driver had to overcome his/her instinctive impulse to release the pressure on the throttle, and press on faster instead. Then, magically, the car became stable and exited the corner with unbelievable speed.
|Nismo #500, not an original badge or sub wing.|
To meet homologation procedure to participate in Group A racing, Nissan Motorsport (NISMO) developed its version of the GT-R – “the NISMO BNR32”. It was launched on February 22, 1990. If the first version of the GT-R was more street car than racer, the NISMO model was just the opposite; it was a car for weekend track days, to be precise. NISMO developed this car as a base for the future street-legal and racing N1 cars. To reduce the 1430kg curb weight of the basic model, the air-conditioning, rear wiper, sound system, and ABS were removed. The latter decision reflects the distrust, not so prevalent today, that pro drivers had for ABS. The intercooler grille was also removed to improve the airflow to the intercooler. Curb weight of the NISMO R32 was 30kg lighter than the basic model, down to 1400kg.
One very important feature of the new car was its steel-bladed TB280 turbos, replacing the ceramic ones (Compressor: housing T04B, A/R 0.42, compressor wheel T3, trim 62T; Turbine: T25, A/R 0.64, turbine wheel T25, trim 79T). This change allowed increasing boost from the basic model’s factory-tuned 11psi (0.78kg/cm2) to more than one bar. Each of the twin turbos was able to boost the power to 300ps. It was enough for the Group A, which required up to 550ps. However, the NISMO had the stock 280ps specification, as did all other street-legal versions of the BNR32. To install the new turbos the exhaust manifold was modified by increasing the surface area of the flanges attached to the turbos and increase diameter to manage the larger volume of the exhaust gas. There were also some aerodynamic changes: additional openings in the bumper to increase airflow to upper part of the intercooler, a lip (a mole) on the front edge of the hood, a spoiler under the rear wing, and “a sill protectors” in front of the rear wheels .
The BNR32 NISMO, which was available in Gun Grey Metallic (#KH2) only, is a very collectable car; just 560 were sold.
March 18, 1990 was very special day; the day, when the R32 GT-R had to fulfill its mission – to dominate in the Group A of the Japanese Touring Championship. The new GT-R was an all-wheel drive machine and that in 1990 was weird questionable in eyes of the racing fans and pros.
|Calsonic Group A R32 GT-R|
However, what was not questionable, and, on the contrary, was obvious – it is the car’s weight; the Skyline was the heaviest car among the Group A machines. For example, the Ford Sierra Cosworth 500RS was 40 kg lighter, and was powered by 550 PS engine. But the new Nissan’s car was “The GT-R”(!) – the legendary name. 41,000 intrigued people came to see the 300 km race at the West Japan Circuit on March 18th 1990. And they were not disappointed. Two GT-Rs, driven by Kazuyoshi Hoshino/Toshio Suzuki of Calsonic and Masahiro Hasemi/Anders Olofsson of Reebok, dominated preliminary and final races. Calsonic won the final race, breaking the course record by two seconds. The Reebok car suffered drivetrain trouble and was second. The Calsonic won five of the six races that year, and became the 1990 season Group A champion. The Reebok car was second. It became obvious, that total domination of the new GT-R was possible thanks to the ATTESSA E-TS system – the main distinguishing feature of the new Skyline.
|Group A R32 GT-R Engine|
In 1991 development of the GT-R was almost finished, with work focusing mainly on improving reliability, thus reducing the cost of participation in the Group A series. Although more teams were attracted to participate in the Group A, the Calsonic and the Reebok were really competing only against each other. This year the title was taken by the Reebok drivers Masahiro Hasemi and Anders Olofsson never retired a race throughout the season. The Calsonic was second – drivers Kazuyoshi Hoshino and Toshio Suzuki retired in the second race (at Suzuki). The Taisan-Klepper GT-R driven by Kenji Takahashi and Keiichi Tsuchiya was third.
In the 1992 season, 16 GT-Rs were entered. Masahiro Hasemi and Hideo Fukuyama drove the championship winning JECS Skyline. The Axia Trampio GT-R driven by Tom Kristensen and Kazuo Shimizu was second. The Kyoseki Skyline GP-1 Plus, piloted by Anders Olofsson and Takayuki Kinoshita, was third in the championship.
1993 was the last Group A season for the GT-R, and the Final Intertec at Fuji was the last race of the season. 94,500 people came to see the race. The BP Oil Trampio GT-R won the race, but the Calsonic car, driven by Kazuyoshi Hoshino and Masahiko Kageyama, won the opening, fifth, seventh and eighth races, taking the championship title. Second was the Nikko Kyoseki Skyline GP-1 Plus (drivers Toshio Suzuki and Sho Iida) and third was the – BP Oil Trampio GT-R (drivers Hisashi Yokoshima and Tom Kristensen).
The GT-Rs together scored 29 consecutive victories in four seasons!
So, what kind of a car was the most glorious racing GT-R – the Group A BNR32? Let’s look at the Calsonic/Impul R32 piloted by Kazuyoshi Hoshino and Toshio Suzuki. This high level of auto racing technology is particularly amazing when you consider that this GT-R started life as a touring car developed at the end of the 1980s. This Group A car’s engine was modified by Racing Engineering Incorporated Nissan Kohki (Reinik) – confirmed by the presence of a Reinik sticker on the engine. The plate covering the ignition coils was removed, obviously to provide additional ventilation of the cylinder head, leaving the sparkplug coils exposed. Note also the aluminum high-pressure air pipes, thick water radiator, strut tower reinforcement attached to the firewall brace bar, fluid reservoirs lined up as in most racing cars, an oil catch tank, Reinik fuel rail, and the aluminum airbox. Note also the fact that there’s no ABS actuator.
Twin stainless steel and titanium exhaust pipes directed the exhaust gases to the left side of the car, under the door. The engine internals and turbos were changed, too. The turbine wheels were steel-bladed, and the compressors were different – Garrets NISMO (those installed on the R32 NISMO version of the street-legal car and, then, on the street-legal N1 versions of the BNR32). The boost pressure was 1.4kg-cm2, and engine output was around 550ps. On some racing circuits boost was increased to 1.6kg-cm2, thus increasing engine power to 600-650ps at 7600rpm and torque to between 55 and 68kg/m at 6000rpm. However, the Group A RB26DETT produced its record output of 650ps just in 1990 (its debut year), at the Monaco and Spa Francorchamps races. The average horsepower for the Group A 1991 RB26DETT was 580ps and, in 1992 – 550ps. It was enough to win the races taking advantage of GT-R’s magic ATTESA E-TS system. So the Reinik and the racing teams focused on the durability of the engines. It is interesting to note that this was not the last time the RB26DETT was upgraded around 600ps, but as it happened later with the NISMO Z-tune 1 and Z-tune 2, the engine’s horsepower was de-tuned closer to 500ps. It looks like this output is a limit of durability of the RB26DETT.
|Reinik Group A Engine|
Reinik’s RB26DETT engineers were very smart in tuning the RB26DETT for different racing series. For Group A, their goal was to reach a high torque around 4000rpm with a rather flat curve up to 6500rpm. This torque curve provided good engine response during exiting corners and in driving situations when the engine lost revs. Also, this power band was useful during maneuvers at mid-speed. The most balanced, reliable and properly made parts, including the engine block, were chosen from hundreds of identical items. The Group A/N1 block is believed to be more rigid than the base block. The crankshaft was more balanced and specially finished to resist wear, and crankshaft lubrication was improved. The Group A pistons had 1.3mm rings instead of 1.5mm rings. This reduced friction and increased power and response. The Group A con-rods were different – stronger (thicker) – and harder material was used for the con-rod bolts. The Group A crankshaft and water pump pulleys had their ratio decreased, improving efficiency in high rpm; they were also lighter. The Group A camshaft pulleys had more adjusting holes than the N1 Taikyu ones. The intake manifold for the Group A car was improved, too, and the intake collector ports were enlarged. The Group A valves look similar to the stock items, but were made from inconel.
|Metal wheel on the left, ceramic exhaust wheel on the right|
Reinik prepared many combinations of compressors and steel-bladed turbines for different racing series. The Group A oil pump was more durable than the stock item, and pumped more than 65l/h at 6000rpm instead of 46.7l/h the stock one. The Group A water pump pumped 240l/min at 4280rpm instead of 160l/min the stock one. It had different size and shape vanes, and cavitation was eliminated. The stock 444cc fuel injectors were upgraded to 555cc ones. More powerful and reliable alternators were used for the Group A engines. A special three-layer baffle plate, efficient during high G-loads, was located in the extended oil pan (volume of oil was now 6.5 liters). The oil temperature and oil pressure were constantly in normal condition.
For the Group A RB26DETT Reinik also made the following modifications: the red line was increased to 8500rpm; the compression ratio was reduced from 8.5:1 to 7.3-7.9:1; the water jacket and water passages in the cylinder block increased in size; the main bearing oil passage was enlarged; beryllium was used for the valves guides and valve seats; valve timing, lift and angle were changed – intake valve lift was increased from 8.5mm to 10.8mm and the angle was increased from 60o to 70o; exhaust lift was increased from 8.28mm to 10.4mm, and the angle was increased from 59o to 68o.
Fuel was supplied by four external pumps, two of which were for the collector (surge) tank and two were high-pressure pumps. The pumps were later moved inside the fuel tank so they were cooled by the fuel.
Practically all parts of the car were reinforced, including the drivetrain parts casings, propeller shaft, left and right drive shafts, all suspension parts, and even the Super HICAS actuator and the steering column.
|Group A R32 GT-R Suspension and Driveline|
To apply the power to the ground, an AP brand, triple-plate clutch was used with a dog-box transmission.
There were several versions of the transmission:
February 1990 – 5-speed:
1: 2.800 2: 1.925 3: 1.523 4: 1.193 5: 0.924 R: 2.625
Final drives with different ratios were used with this transmission: 3.500, 3.545, 3.700, 3.900, 4.375 depending on racing circuit; faster circuit, e.g. Fiji required higher final drive ratio, the slower, like Tsukuba, – the lower one. The front and rear differentials were limited – slip ones.
|This Holinger is a H6S, which was not used in Group A. However, life is better with a sequential|
March 1990 – 6-speed transmission was homologated. It was developed by Australian company – Hollinger: 1: 2.721 2: 2.101 3: 1.667 4: 1.353 5: 1.141 6: 1.000 R: 2.806
Final drives for this transmission were: 4.625, 4.875, 5.143
April 1991 – 5-speed with a slightly lower 5th gear, than in the previous 5-speed version:
1.0 with a higher final drive – 3.364
April 1992 – 5-speed with slightly higher 1st gear: 2.552.
These ratios kept the rpm above 5500 if the gearshift was made above 7300rpm, which allowed high turbo spool-up and permanent high torque output from the engine.
|Coolers under a Group A R32 GT-R|
Besides the engine oil cooler, which extended the engine oil capacity to over seven liters, all parts of the drivetrain had their own oil coolers with electric pumps. Two oil coolers with air scoops located in front of the rear axle were for the transmission and rear differential. The oil cooler located behind the rear axle, also with an air scoop, was split into two separate oil coolers: one for the transfer box, and another for the front differential.
|Notice the Group A car has trailing brake calipers. This allows them to get air to the rotors easier than a leading caliper, like the street car.|
Starting from 1990 a number of different front and rear brakes and brake air cooling ducts, used on the car during its 4-year racing career. The car had either Brembo, or AP, or Alcon 4-piston front and 4 rear calipers. It was the first time when the Brembo calipers were used on a GT-R. Usually, the front rotors were grooved ventilated 376mm x 36mm Alcon, and the rear were grooved ventilated 305mm x 25.4mm AP rotors. But sometimes size of the rear rotors was increased to astonishing 376mm. The brake master cylinder was exchanged for the twin one.
In 1991 the water-cooled 4-piston calipers were adopted. Then the air-cooled were used again with the AP 6-piston front calipers and 4-piston rear calipers.
This is an indicator that the braking was a problem for a heavy Skyline. It is a lesson, that should be learned by designers of future GT-Rs.
The dimensions of the Group A BNR32 differed to those of stock versions. The car was wider; 1772.5mm (stock 1755mm), and lower; 1320mm (stock 1340mm). The tracks were wider, with the front much wider than the rear; 1610mm and 1530mm, accordingly (stock front and rear tracks were 1480mm). The wide front tires were not totally covered by the bumper cover. This would have raised the BNR32’s already high drag coefficient. Body stiffness was increased by 200 per cent compared to the stock car by using a roll cage, spot welding, and other body reinforcements. In 1993, body stiffness was further increased (as was that of the stock car). As a result, the BNR32 V-spec stock and racing cars, suffered less from understeer.
|Front upper suspension arm mounting point – Group A R32 GT-R|
There were significant changes in the suspension compared to the stock car. The Calsonic suspension arms were different, for example, and the front suspension tie rods were aluminum. The subframes and suspension parts were reinforced, and the soft stock bushings were exchanged for the pillowball ones. Suspension geometry was also changed: the springs were stiffer; the anti-roll bars were 2-stage adjustable; and the KYB front and rear shock absorbers were 4-way adjustable. Interesting to notice effective diameter of the anti-roll bars (in the homologation papers they were called “stabilizers”) used the Group A BNR32s on different races. In contrast to the stock BNR32, the front bars were thicker, than the rear; front: from 25.4mm to 60.0mm (!); rear: from 19.4mm to 34.0mm. It indicates that understeer was not a problem for the racing GT-R. The body rigidity and probably, the torque distribution and the wheel camber were the main tools of minimizing the understeer. Front negative camber usually was adjusted to five degrees 30 minutes, the rear to 3 degrees 30 minutes. In general, it was typical for the Group A R32s to have a lot of front and rear negative camber; the front wheels had a lot of camber thrust to provide a crisp turn-in.
The front suspension had 2mm toe-in and the rear toe was 0 because the Super HICAS was operational. Stock steering ratio -1:13.7- also was changed for faster one -1:12.4. Heavy duty power steering pump was used.
|Super Hicas Rear steering Group A R32 GT-R|
Talking about the exterior, the car’s hood had a lip on the front edge (a mole), which significantly improved the airflow into the upper aperture. However, the almost stock aerodynamics of the Group A cars was a serious negative feature, because maximum speed on straights was sometimes more than 300kmh (190+mph), which made the car float.
The headlights were lighter than stock, the door mirrors had an aerodynamic shape, and there were fairings in front of the rear wheels (found on all Group A R32s), conditionally called “sill protector”.
The driver’s seat was moved rearwards to improve weight distribution.
|One of the air jacks|
The car was equipped with an air jack, and the instrument cluster had a digital display for oil temperature, water temperature, oil pressure, and differentials, gearbox and transfer unit oil temperatures. The brake balance was adjustable from the cockpit. Also, the display had a warning function which indicated malfunctioning systems of the car.
The interior was equipped with a torque split controller with three settings, each offering very detailed response time and torque distribution adjustment. For example, setting 3 was developed for Calsonic driver Kazuyushi Hoshino, based on Masahiro Hasemi’s and Kazuo Shimizu’s experience. The E-TS computer was located behind the driver’s seat, as was the ECU.
|Stock rear view mirror in a Group A car|
According to Group A regulations, the wheels could be two inches wider than the stock wheels of the street-legal commercial version of the car. So, the Calsonic had 10 x 18 JJ Impul brand 2-piece wheels with Bridgestone Potenza 265/680 R18 slick tires. Despite certain negative features of the Group A BNR32, it was an incredible machine. It became the most glorious GT-R among all the following ones. Nothing came close to it! Oh, yeah! Hold on, we forgot to mention that you could buy the 550 PS Group A-spec BNR32 from NISMO…, if you have $550,000.
- FIA Group A NISMO Nissan Skyline GT-R Homolgation Papers
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Published at Fri, 08 May 2020 12:22:00 +0000