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Nismo Development Background – Interview with Okamura-san

October 6, 2008

The Nismo Club Sports Package was developed in the goal of durability in mind. The price tag however calls forth the question, what is the deal with these parts? We’ve talked to Junpei Okamura-san, head of Nismo development on this matter.

The Purpose of Development?

The first goal in development of the package was to continue to improve on the already great Nissan baseline. To improve performance but at the same time not reduce durability or absolute safety.

So it can be said that to meet these goals the package should improve circuit and sports driving performance, basically lower lap times by increasing stability and efficiency. Of course it’s not just pure speed that we need to pursue to meet our goals, we need to focus also on control in corners, steering response, braking performance and so on. Nismo’s chassis package fine tunes the GT-R in this department.

Dampers

The GT-R’s standard Damptronic suspension is great – so Nismo adopted the same basic suspension in both manufacturer and basic hardware. The benefit of using Damptronic suspension are many but the ability to keep the function of the dash suspension mode setting switch is great. Nismo intend their dampers to be used on in R-Mode at the circuit but just as with the stock suspension the Comfort setting gives a much more compliant ride.

The dampers aren’t exactly the same in every way to standard however and the main valves have been changed to tune damping force in R-Mode to Nismo’s specifications. These changes keep the GT-R more planted under fierce acceleration as well as keeping body roll in check in the corners. The tendency for the nose to pitch forward while braking is also reduced.

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Source: GTR-World.net – Nismo, Okamura-san Interview
Images: Nismo and Nismo via GTR-World.net

Springs

Springs front and rear are increased in stiffness to again reduce roll in corners, acceleration and braking. Even with this increase in stiffness the ride quality is still acceptable. A good balance between stiffness and driveability has been struck.

The spring rates are 18.5 kg/mm2 front and 9.6 kg/mm2 rear. These Nismo springs maintain standard vehicle ride height. Some may ask why they chose to leave the ride height standard? The main reason behind this is to maintain the proven durability of the car. To change the vehicle ride height would have a knock on effect for other components and would require significant testing before they could guarantee it. This testing is time consuming and costly and would result in the end price of the springs being higher to the customer.

Are some lowering springs being planned? For now it has been proposed but will require some changes to the dampers to do properly.

Tires

Tire choice was certainly an important decision for Nismo to make for the chassis tuning package and it was tackled in earnest. The normal road tires developed for the GT-R show a tendancy to understeer cornering at the limit. To improve this Nismo worked with Bridgestone on developing the RE070R tires. The rigity of the tread surface is increased and the tread pattern is slightly different than the standard tires. In addition the compound of the tire is changed to improve grip.

In testing these tires gave a surprising life span of more than 40 laps at race speeds and showed a comparable life span to the standard Bridgestone tires for normal road driving.

On both wet and dry circuit work these tires were found to be the same or better than the standard tires, hence Nismo is able to offer the guarantee of safety on these.

Wheels

Lightening the wheels was a goal from the outset but increasing rigidity was a must also. Another goal that was focused during development was keeping the same impact resistance as the standard wheels. These goals were met and 1.6kg per front wheel and 1.4kg per rear wheel was saved. In serious racing these wheels were found to be extremely durable as well.

End of Part 1

Check out the rest of the photos below from part 1 and then stay tuned for part 2 to come in the next few days.

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