Guide: Dome Zero P2
Background
Although the Japanese Ministry of Transportation refused to type approve Dome’s original Zero prototype on safety grounds, the car’s widespread popularity led to an influx of cash from licensing deals signed with toy makers.
As a result, Dome were able to open a new head office in Kyoto, develop a second iteration of the Zero and even build a Group 6 racing car to contest the 1979 Le Mans 24 Hours (the Zero RL).
To circumvent the strict homologation requirements for domestic manufacturers, Dome boss, Minoru Hayashi, came up with a ruse.
At the time, it was relatively simple for Japanese buyers to obtain export-only vehicles produced by domestic manufacturers via the grey market. As laws were very lax, a small underground industry had emerged to meet demand. Known as ‘Gyakuyunyu’ (reverse import), Hayashi believed such an approach would allow sales of the Zero into the Japanese market without regulatory approval.
A new company, Dome USA, was established to develop the new Zero P2 in line with North American regulations and perform the necessary certification work. As far as the Japanese authorities would be concerned, the Zero P2 was designed specifically for export.
Hayashi expected to produce a limited run of 30 cars.
Chassis
To free up additional cockpit space, the Zero P2’s steel semi-monocoque chassis had its wheelbase extended from 2400mm to 2450mm. For the same reason, track was widened by 45mm at the front and 55mm at the rear.
Various structural reinforcements were also made to improve safety.
As before, suspension was fully independent all round with double wishbones, coil springs and Hayashi Racing shocks.
Anti-roll bars were fitted either end and Girling disc brakes to each corner. The discs were ventilated at the front and solid at the back (where they were mounted inboard).
The Zero P2’s cast alloy wheels were manufactured in-house by Dome. They had a 13-inch diameter at the front and taller 14-inch diameter at the rear. The rims were once again shod with Dunlop Super Sport tyres (185-60VR13 and 225-55VR14 respectively).
Engine & Gearbox
Although turbocharged Nissan and Toyota straight-six engines were under consideration for production, the Zero P2 prototype used the same Nissan L28 motor found in its predecessor.
The L28 was a two-valve water-cooled straight six with a single-overhead camshaft, cast-iron block and aluminium head. It displaced 2753cc thanks to a bore and stroke of 86mm and 79mm respectively.
Compression was 8.3:1 and three Solex twin choke C40 carburettors were fitted.
Peak output was 145bhp at 5200rpm and 166lb-ft at 3600rpm.
The gearbox was 5DS-25/2 five-speed manual supplied by ZF in Germany.
Bodywork
Despite the fact the original Zero had appeared a little behind the times with its pure wedge profile, no drastic changes were made to the car’s overall appearance.
At first glance, the Zero and Zero P2’s fibreglass bodies appeared identical.
The key difference between the two variants was all to do with better impact protection. New lower body sections at the front and rear now housed large impact-absorbing Polyurethane bumpers designed to meet strict US regulations.
The overall affect of the various chassis and body modifications meant the Zero P2 was 55mm longer, 5mm wider and 10mm taller than before.
Interior
In an attempt to productionise the Zero, arguably the most dramatic design changes were made to the interior.
The dash featured a redesigned instrument binnacle and now housed controls for the ventilation and audio system off to the left. To the right was a smaller bank of touch controls than found in the original Zero prototype.
Readouts were a mix of digital graphics and LED notifiers.
The P2 also came with a central instead of right-hand gear change.
The distinctive triangulated twin spoke Hayashi Racing steering wheel was retained.
Thanks to the extended wheelbase and wider track, cockpit space was a little better than before.
Weight / Performance
The longer wheelbase along with various bits of additional equipment led to a 30kg weight increase (950kg instead of 920kg).
With the normally aspirated engine in place, a circa 140mph top speed was anticipated along with a 0-62mph time of around seven seconds.
A more potent turbocharged version had the potential to go considerably quicker.
Launch
A pair of Zero P2s were constructed and the new car was displayed at the Chicago and Los Angeles Motor Shows in 1979.
One of the cars was even tested by Road & Track where it received a very positive review.
However, efforts to gain type approval failed and the Zero was never produced for commercial sale. One of the many problems was that the P2’s bumpers did not meet the minimum US height requirement.
Finally accepting defeat, Minoru Hayashi abandoned the programme and switched his company’s focus back to racing.
Text copyright: Supercar Nostalgia
Photo copyright: Dome - http://www.dome-museum.com
