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 mentioned in last month’s issue, we recently drove the new 2000GT-R and 2000GT Hardtop in a caravan for about 900km through the mountains and fields around Tokyo, and were especially impressed by the GT-R’s dynamic performance and its outstanding handling for a practical vehicle. So this month, we once again pulled out the GT-R Hardtop and made plans to record accurate data, including top speed, at Yatabe, and to fully test the limits of its maneuverability at FISCO, and we put them 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 it to Yatabe (C/G, May 1969), but the engine was not working properly and it was faster in fourth gear than fifth, and we had to cancel the acceleration tests due to clutch slip. A few days later, we borrowed the repaired GT-R again, but to our surprise, Tokyo was hit by the heaviest snowstorm since the weather station began monitoring snowfall in March, and the GT-R was buried under 30cm of snow for two days. The GT-R Hardtop we tested last month was in very good condition, but we were very worried about whether it would maintain this good condition for the month leading up to this test. After all, we knew that the only test GT-R in Nissan’s PR department was being used hard by a group of magazine experts every day, so there was no time to even maintain it.
There is nothing more disappointing than going all the way to Yatabe only to find that the car is not in good condition and unable to conduct a full test. So I 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 I was finished writing the manuscript for the special edition issue on the Tokyo Motor Show, I rushed to Murayama and received a crimson red GT-R from Mr. Tonoi Nobuyuki of the No. 9 Testing Division (a test driver who had made a name for himself in races during the GT-B era). This car was an even earlier production model (chassis number 000012) than the orange car (chassis number 000021) that I had tested last month, and was fitted with a 155ps regular-gasoline engine. It had been driven about 5,100km and had been thoroughly run-in, but it was still 100% stock and should have achieved the expected design 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 measurements at Yatabe showed that the impact on power performance was very minor. 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, I mentioned that this engine is much more flexible than in the 160ps GT-R sedan that I tested previously, but this red hardtop is even more tenacious at low speeds. As soon as I left the Murayama Factory, I was caught in a rush-hour traffic jam, and it took me an hour and a half to reach my destination, which was only 16km away. However, I was able to take my foot off the throttle, idle at 1000rpm, and drive slowly in first gear, which was a great help. The condition of the engine was also very stable and remained constant throughout the approximately 1200km test run under all conditions. For example, even in such 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 even on the rare occasions when I found a gap in the line of cars and accelerated suddenly, the engine would rev “explosively” as usual when I stepped on the gas.
As mentioned above, when we brought a GT-R sedan to Yatabe in a previous test, the engine was not well-maintained and did not produce enough 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 to bring this data to C/G readers. This was our public promise, and it has become something of an obsession for me personally.
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 perfect. After a thorough warm-up, six liters of engine oil was heated, the fifth wheel was fitted, and we headed out onto the course. After a few laps to warm up the transmission, we began full-scale high-speed driving. The C/G test method is very strict, and times are taken on a precisely measured 2km 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 only 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, this is considered to be the real ability of the regular-gasoline GT-R, but frankly, it was a little below our expectations. However if the optional tail wing is installed to reduce the air resistance (which is said to be quite effective at speeds above 120km/h), we believe that it will be possible to achieve a top speed of around 190km/h (although the catalog value of 195km/h will be impossible).
The gear ratio setting seems a little too high for the 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 the engine is said to be tenacious, the usual range for really fast driving is around 4000 to 7000rpm. The standard final drive ratio is 4.44, but if I were to use the GT-R for practical purposes, I would not hesitate to install the optional 4.88 gears. Of course, the top speed will increase, but this is not relevant in practical use. The issue is that I want to improve acceleration performance and flexibility at low and medium speeds. As far as I can judge from the test car this time, the engine can easily rev up to 8000rpm, so by lowering the final gear by 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 use.
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) I 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 low-lead gasoline slightly outweighs the positive effects of the hardtop’s reduced weight and air resistance.
When taking the acceleration times, I felt that a clean racing start with the GT-R requires very delicate judgment and footwork. First of all, the weight of the car is absolutely 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 slows down for a moment. The time of 16.6 seconds is achieved when an ideal start is made with very little 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 and fifth gears are close together, making it ideal for driving at a high average speed while shifting frequently. For example, when comparing the overtaking acceleration time from 60 to 100km/h, which is often used on expressways, for the top three gears, it takes 12.6 seconds in fifth gear, 9.5 seconds in fourth gear, while it takes only 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 even knock 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 low compression ratio (9.0, down from 9.5) and the use of low-lead 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 has improved practicality. However, if there is a disadvantage in practical 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 used this time), 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 the richness of the gas, 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 1200km was only 5.6km/l (odometer corrected), but this was because, as usual, we always drove at the highest speed possible under the circumstances.
The best result was 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, I got a result of 6.7km/l. When I asked a GT-R (160ps sedan) owner who frequently travels to and from Suzuka on the Tomei expressway, he told me 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 cornering speeds that can be tested on public roads, there is very little understeer, little roll, and 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, the tread is extremely hard, and kickback from the road surface is extremely strong. They are weak against road camber and vertical bumps, and are similar to racing tires in that they impair straight-line stability. On surfaces other than the good roads on the Tomei Expressway, you need to hold the steering wheel firmly and concentrate (but on good surfaces, you can let go of the steering wheel even at top speed, and it’s not affected by crosswinds at all). The steering wheel, which used to have a wood rim, was wrapped in leather when the hardtop debuted, but gloves are still a necessity.
At least on dry roads, the grip of these tires is high and they don’t squeal easily, so the only safe (and legal) way to test the GT-R’s cornering limits is to take it to the circuit, and we thoroughly enjoyed high-speed cornering at FISCO. It was clear in the first corner of the 4.3km course, the series of high-speed left-handers that followed, and the 100R after the hairpin that even with the standard tires, you can turn beautifully in a drift-like posture by balancing the cornering power of the front and rear wheels with the throttle and steering. However, the suspension, which we thought would hardly roll at all when driving on normal public roads, rolls quite a bit with the large lateral g that is 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 recover with the sharp steering and throttle.
On the other hand, in slow corners such as hairpins (where the road surface is extremely slippery), the GT-R’s “touring car” characteristics become a major disadvantage. First, the understeer is strong, the car rolls a lot, and the rear wheels easily break traction when full power is applied in second gear. Although the steering usually seems quite quick, a higher ratio is preferable for correcting such situations. I ran the car with a high tire pressure of 2.3kg/2.3kg, 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 weak 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 disc/drum brakes without servos, because racing drivers dislike the slight lag time of servos. Therefore, the pedal force is generally high, and even a gentle stop (about 0.3g) at a traffic light requires a heavy 20kg foot. The effect is gradual according to the pedal force, and it is good that 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 the brakes, so there was no problem at all, but when I drove around the winding roads of Shiga Kogen for about an hour, its pedal force gradually increased and I began to feel slight vibrations in the pedal. At Yatabe, I performed a 0-100-0 test in the C/G style, which is to say, accelerate to 100km/h, stop at a deceleration rate equivalent to 0.5g, immediately accelerate and repeat the same stop 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 high brake reliability, I think this method is reasonable. The results show that the GT-R is not fade-free afterall. 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, I think it would be better to combine a stronger, more fade-resistant pad and a servo. In its current state, it can be scary even in in the city when the car in front brakes suddenly, especially when fully loaded.
I’ve spent a lot of time on handling and power performance, so I don’t have the space to write about comfort. To briefly mention what I noticed, the bucket seats are generally well-shaped (though I prefer them to be tilted back a little more), and you don’t get too tired even after a long time in them. The comfort of the rear seats is almost comparable to that of a sedan. What’s improved in the hardtop is the light switch, which goes back to the old Prince layout and allows all lights to be turned on and off with the lever on the right side of the steering column. The heater, defroster, and radio are not included as standard, but the GT-R’s designer must be a heavy smoker, as it comes with a lighter. Also, the stroke of both the clutch and the brake pedals is too large.
Now, if I were to buy a GT-R for practical use, I would make it with the following specs: 4.88 final drive ratio, 5J rims and 6.95H-14 Bridgestone Super Speed 2 tires from the Z432, racing brake pads and servos, a quick 15.2:1 steering ratio, iodine lights, and a quieter exhaust noise that won’t raise any eyebrows when warming up in a residential area in the early morning. This completes a hard-core grand tourer that is great fun to drive.