Nissan Skyline 2000GT-R Hardtop (1971)
Publication: Car Graphic
Format: Road Test
Date: January 1971
Author: “C/G Test Group” (uncredited)
Summary: A semi-racing hardtop with a six-cylinder twin-cam 24-valve engine. No knock even with regular fuel, relatively flexible, only minor impact on performance, extremely high maneuverability despite bias-ply tires, enjoyable on the circuit. Excellent steering response but lots of kickback, rear seat comfort comparable to a sedan, heavy controls, limited practicality, high price.
Road testing the Skyline 2000GT-R Hardtop
As we wrote in last month’s issue, we recently drove the new 2000GT-R and 2000GT Hardtops in a caravan for about 900km through the mountains and countryside around Tokyo, and were especially impressed by the GT-R’s dynamic performance and its outstanding handling for a practical vehicle. So we arranged to bring out the GT-R Hardtop once again this month, this time to record accurate data at Yatabe, including top speed, and to fully test the limits of its maneuverability at FISCO, and put our plans into action.
Looking back, we had not been so lucky as far as past tests of the GT-R were concerned. Immediately after the GT-R sedan debuted in the spring of 1969, we brought one to Yatabe (C/G, May 1969), but its engine was not working properly, making it slower in fifth gear than in fourth, and we had to cancel the acceleration tests due to clutch slip. A few days later, the GT-R was repaired and we borrowed it again, but to our surprise, Tokyo was hit by the heaviest snowstorm since the weather station began monitoring snowfall in March, and instead of returning to Yatabe, the GT-R was buried under 30cm of snow for two days. By contrast, the GT-R Hardtop we drove last month was in very good condition. But we worried about whether it would stay in good condition for the month leading up to this test. After all, we knew that it was the only test GT-R in Nissan’s PR department, and it was being used hard by groups of magazine testers every day, so there was no time to even perform maintenance.
There are few things as disappointing as going all the way to Yatabe only to find that a car is not in good condition, and being unable to conduct a full test. So we explained the situation to Mr. Sakurai Shinichiro of Nissan’s No. 4 Vehicle Design department, the father of the GT-R, and he agreed to provide us with a car from the production line that was being used for random testing at Murayama. As soon as we finished writing the manuscript for the Tokyo Motor Show special issue, we rushed to Murayama and received a crimson red GT-R from Mr. Tonoi Nobuyuki of the No. 9 Testing Division (a test driver who made a name for himself in racing during the GT-B era). This car was an even earlier production model (chassis number 000012) than the orange car (chassis number 000021) we drove last month, and was fitted with a 155ps regular-gasoline engine. It had been driven about 5,100km and was thoroughly run-in, but it was still 100% stock and was expected to achieve the official specified output. The testing division uses regular gasoline, and we used low-lead gasoline (around 92 octane) for our test.
It’s hard to believe, but this semi-racing engine can run on regular gasoline without any problems, and the tests at Yatabe showed that the impact on power performance is minimal. The regular-fuel specification engine has been machined around the piston crank to increase the combustion chamber volume, and the compression ratio has been reduced from 9.5 to 9.0. At the same time, the ignition timing has been retarded from 15° BTDC/1000rpm to 10° BTDC, and the distributor advance characteristics have also been changed. Power and torque are reduced from 160ps/7000rpm and 18.0kgm/5600rpm for the high-octane specification to 155ps/7000rpm and 17.6kgm/5600rpm, respectively.
In last month’s issue, we mentioned that the test car’s engine was much more flexible than in the 160ps GT-R sedan that we tested previously, but this red hardtop is even more tenacious at low speeds. As soon as we left the Murayama Factory, we were caught in a rush-hour traffic jam, and it took us an hour and a half to reach our destination, which was only 16km away. However, we were able to gently release the clutch, idle at 1000rpm, and creep along slowly in first gear, which was a great help. The engine’s condition was also very stable, and remained constant throughout the approximately 1,200km test distance. For example, even in a long traffic jam, the water temperature (this car is a little sensitive to cold, and is usually between 50°C and 80°C) only rose to 80°C, and on the rare occasions when we found a gap in the line of cars and accelerated suddenly, the engine would rev “explosively” as usual when we stepped on the gas.
As mentioned above, when we first brought the GT-R sedan to Yatabe for testing, its engine was not well-maintained and did not produce the expected power at high speeds, so the top speed was only 179.6km/h. Since then, we have been trying to confirm the GT-R’s true capabilities and bring this data to C/G readers. This was our public promise, and it became something of an obsession for us personally.
This time, the Yatabe test was conducted under near-ideal conditions. The car was perfectly prepared, the weather was clear with almost no wind, and the temperature and humidity were mild. After a thorough warm-up to bring the six liters of engine oil up to normal temperature, the fifth wheel was fitted, and we headed out onto the course. After a few laps to warm up the transmission, we began instrumented high-speed testing. The C/G test procedure is very strict, and times are taken on a precisely measured 1km straight section and a 5.5km lap course, and the average speed for each is calculated. At the top speed, the fifth wheel type electronic speedometer is used only as a reference (although in reality it is surprisingly accurate, and the indicated speed and the calculated average speed are perfectly consistent when there is no wind).
In the end, the average speed for the 1km flying run was 185.6km/h, and the average speed for the 5.5km lap was 184.0km/h due to some wind influence. For the reasons explained above, we consider this to be the true, representative ability of the regular-gasoline GT-R. To be honest, it was a little below our expectations, but if the optional tail wing is installed to reduce air resistance (which is said to be quite effective at speeds above 120km/h), we believe it would be possible to achieve a top speed of around 190km/h (although the catalog value of 195km/h will still be impossible).
The GT-R’s gear ratio setting seems a little too high for its weight and power output, since the top speed is the same in fifth and fourth gear, and the engine speeds in these gears are only about 6000 and 7000rpm, respectively (7000-7500rpm is the yellow zone). Even though we describe the engine as tenacious, the usual range for really fast driving is around 4000 to 7000rpm. The standard final drive ratio is 4.44, but if we were to use the GT-R for practical purposes, we would not hesitate to install the optional 4.88 gears. Of course, the top speed would increase, but this is not relevant in practical use. More importantly, it would improve acceleration performance and flexibility at low and medium speeds. As far as we could judge from the test car, this engine can easily rev up to 8000rpm, so by lowering the final drive ratio one step, you should be able to make better use of the high speed range in third, fourth, and fifth gears, making it even easier to drive.
Of course, even in its current state, the GT-R’s acceleration performance is impressive for a 2-liter heavyweight car. It does 0-400m in 16.6 seconds, 0-1km in 31.1 seconds, and just reaches a speed of 160km/h by the end of that 1km. However, compared to the GT-R sedan (160ps) tested previously, it is 0.2 seconds slower from 0-400m and 0.2 seconds slower from 0-100km/h. It seems that the loss of power due to the use of regular gasoline slightly outweighs the positive effects of the hardtop’s reduced weight and air resistance.
When taking the acceleration times, we found that a clean racing start with the GT-R requires very delicate judgment and footwork. First of all, the absolute weight of the car is heavy (1278kg including two people and test equipment), the low-speed torque is weak, the gear ratio is relatively high, and it is equipped with a limited-slip differential, so even if you increase the rotation speed to 6000rpm and gradually engage the clutch, the rotation speed drops to 4000rpm and acceleration bogs down for a moment. The best time of 16.6 seconds was achieved with an ideal start with very slight wheelspin, and the time is about 0.2 seconds slower if there is no wheelspin.
The gear ratios of the 5-speed gearbox are perfectly suited for practical use. In particular, third, fourth, and fifth gears are close together, which is ideal for driving at a high average speed, shifting frequently to make full use of the performance. For example, when comparing the overtaking acceleration from 60 to 100km/h, a range often used on expressways, the times are 12.6 seconds in fifth gear, 9.5 seconds in fourth gear, and just 6.6 seconds in third gear. Similarly, the times for overtaking from 80 to 120km/h are 13.3 seconds, 10.0 seconds, and 8.5 seconds, respectively. Third gear has the widest range of use, as it does not knock even when accelerating from 40km/h (about 2000rpm) in the city, and the upper limit extends to 150km/h. The overdrive fifth gear can also be used from a surprisingly low speed (60 km/h) and it can be used at 100km/h on an uphill gradient like that encountered on the Tomei Expressway, with enough power in reserve to maintain speed while climbing.
The lower compression ratio (9.0, down from 9.5) and the use of regular gasoline have only a slight effect on performance, as mentioned above, and it can even be said that the improved flexibility in the low-speed range improves practicality. However, if there is a disadvantage in everyday use, it would be the increased fuel consumption. When comparing the fuel consumption during constant speed driving (C/G drives a 1km section and measures it with an electromagnetic fuel consumption meter) with the 160ps GT-R sedan tested earlier (which also weighed 1320kg at the time of testing, 42kg heavier than the hardtop), the results are as follows (the figures in parentheses are for the sedan, and all figures are for fourth gear): 11.4km/l (11.9km/l) at 60km/h, 8.6km/l (9.4km/l) at 100km/h, and 5.9km/l (6.4km/l) at 140km/h. Suspecting that this was due to richness of the fuel mixture, we put it through a CO2 tester, but surprisingly it passed with a result of 4.0% (idle limiters were installed on the three Solex units at the time of production). The total average for the test distance of 1,200km was only 5.6km/l (odometer corrected), but this was because, as usual, we always drove at the highest speed possible under the circumstances.
We saw our best fuel-economy result when we accompanied the test of the Galant GTO MII on the Tomei Expressway to Omote Fuji and Kawaguchiko. On a 399km highway trip back to Tokyo via the Chuo Expressway, we recorded 6.7km/l. When we told a GT-R (160ps sedan) owner who frequently travels to and from Suzuka on the Tomei expressway about this, he told us that his average on the highway is about 7.5-8.0km/l. The tank holds 100 liters, and the GT-R has a powerful electromagnetic pump in the trunk that makes a constant clicking noise. If you get stuck in traffic, you can hear the continuous loud operating sound of fuel being pumped in, even when the car is stopped, and it makes this C/D editor, who is naturally stingy with fuel (I was born in the 1930s), feel intimidated.
The GT-R’s handling is second only to the Fairlady Z among domestic mass-produced cars. The first thing you notice when you get on the road is that the steering response is sharper than you would expect from a car of this weight and size. At the cornering speeds that are possible on public roads, there is little roll and very little understeer, and the steering effort is within appropriate limits (except when parking). The Bridgestone Super Speed 2 bias-ply tires contribute greatly to handling, at the expense of ride comfort. Even at 2.0kg/2.0kg air pressures, their tread is extremely stiff, and kickback from the road surface is extremely strong. They are weak against the effects of road camber and vertical bumps, and are similar to racing tires in that they impair straight-line stability. On surfaces other than smooth roads like the Tomei Expressway, you need to hold the steering wheel firmly and concentrate, but on good surfaces, you can take your hands off the steering wheel even at top speed, and it is not affected by crosswinds at all. The steering wheel’s previous wood rim was changed to a leather-wrapped one when the hardtop debuted, but gloves are still a necessity due to the strong kickback.
On dry roads, at least, the grip of the Bridgestone tires is high and they don’t squeal easily, so the only safe (and legal) way to truly test the GT-R’s cornering limits is to take it to the circuit. We took the test car to FISCO, where we thoroughly enjoyed exploring its high-speed cornering limits. From the first corner of the 4.3km course, the series of high-speed left-handers that followed, and the 100R after the hairpin, it was clear that even with the standard tires, you can turn beautifully in a drift-like attitude by balancing the cornering power of the front and rear wheels with the throttle and steering. However, the suspension, which we expected would hardly roll at all from our experience driving on normal public roads, rolls quite a bit with the large lateral g that are possible on a circuit, and because there is plenty of power, there is always the possibility of roll oversteer. However, this transition occurs gradually, so it is relatively easy to catch with the sharp steering and throttle.
On the other hand, in slow corners such as hairpins (especially when the road surface is extremely slippery), the GT-R’s “touring car” characteristics become a major disadvantage. The understeer builds up strongly, the car rolls a lot, and the rear wheels break traction easily when full power is applied in second gear. Although the steering usually seems quite quick, a higher ratio would be preferable for correcting such situations. We ran the car with high tire pressures of 2.3kg/2.3kg at FISCO, and even after driving for nearly an hour, the tires were only slightly warm, and the wear on the edges was very slight. However, the 4.5J rims are a little narrow for this car’s weight. The Fairlady Z432’s 5J rims and 6.95H-14 tires should fit as is, and installing them should improve the car’s maneuverability even more.
The GT-R is equipped with unservoed disc/drum brakes (a servo is optional), because racing drivers dislike the slight lag time of servos. Therefore, the pedal effort is generally high, and even a gentle stop (about 0.3g) at a traffic light requires a heavy 20kg foot. The braking effect is progressive according to pedal force, and even if you step on the pedal hard from high speed, it decelerates powerfully in a stable posture. The FISCO course puts a light burden on brakes, so we had no problems at all, but when we drove the GT-R around the winding roads of Shiga Kogen for about an hour, the pedal force gradually increased and we began to feel slight vibrations in the pedal. At Yatabe, we performed C/G’s usual 0-100-0 test, in which we accelerate to 100km/h, stop at a deceleration rate equivalent to 0.5g, immediately accelerate, and repeat this 10 times in a row. In this test, the faster the car, the more frequently the brakes are applied, and since high-speed cars require more reliable brakes, we think this method is reasonable. The results showed that the GT-R is not fade-free after all. The initial pedal force of 22kg suddenly increased to 36kg on the seventh stop, and finally doubled to 42kg by the tenth stop. For a practical car meant to be driven on public roads, we think it would be better to combine a stronger, more fade-resistant pad with a servo. In its current state, there can be scary moments even in in the city when the car in front brakes suddenly, especially when carrying a full load.
We’ve spent a lot of time on handling and power performance, so we don’t have the space to write much about comfort. To briefly describe our impressions, the bucket seats are generally well-shaped (though we’d prefer reclining seatbacks), and you don’t get too tired even after sitting in them for a long time. The comfort in the rear seats is almost comparable to that of a sedan. A major improvement in the hardtop is that the light switch has finally returned to the old Prince location on the stalk on the right side of the steering column, allowing all lights to be turned on and off without taking your hands off the wheel. A heater, defroster, and radio are not included as standard, but the GT-R’s designer must be a heavy smoker, as it does come with a cigarette lighter. Also, the stroke of both the clutch and the brake pedals is too large.
We discussed how we would spec the GT-R if we were buying one for our own practical use, and decided we would equip it with the following options: 4.88 final drive ratio, 5J rims and 6.95H-14 Bridgestone Super Speed 2 tires from the Z432, racing brake pads with servo, quick 15.2:1 steering ratio, iodine lights, and a quieter exhaust to avoid raising eyebrows when warming up in a residential area in the early morning. These finishing touches would complete a hard-core grand tourer that is great fun to drive.
Postscript: Story Photos
