Build Your Own R35, Week 17

by akasakaR33
5 years ago

Summary of this week’s contents:

1. R35 GT-R Story

Porsche Disputes the 7 Minute 29 Sec ond 03 Run!

The buzz on the internet started in early October 2008, when Porsche attempted to replicate the 7 minute 29 sec 03 time set by the 2008 model year GT-R on April 17, 2008. The Porsche 911 chief engineer, in Australian magazine “Carsguide,” made the claim that the record was not set by a production car. He suggested that Nissan had fitted the car with semi-slick tires, and asked how Nissan was able to set that time.

Porsche had purchased a US spec model, with brand new tires, and drove it at Nurburgring on the same day within 2 hours of testing their own 911 Turbo and 911 GT2, both which ran on radial Michelin Sports Cup tires. The Porsche team got 7 minutes 54 sec for the GT-R, 7 minutes 38 sec for the 911 Turbo, and 7 minutes 34 seconds for the GT2. However the cars were not driven by their normal test driver Walter Rohr but by one of the chassis engineers.

The chief engineer explained that the “GT-R is a good car. Not intending to say anything negative. However it is 20 kgs heavier that the 911 Turbo, with similar power. And the reason we comparison tested was because we were impressed with Nissan’s announcement.”

So in a way, Porsche was benchmarking against the GT-R! But what concerned Nissan was, whether the test car had been broken in correctly, whether the transmission, clutch and engine had been properly adjusted – at the time, no NHPC had existed in Europe as the car was not officially sold there. Recall that the chief engineer had claimed all brand new tires.

In response, Mizuno-san initially replied “what a nuisance” but also re-stressed that “the lap record was done with a normal production car.” “For us to test a car with special tires or suspension, is meaningless. The GT-R concept is Anywhere, Anytime, Anyone – so there is meaning in testing a car that one of our customers can also buy – not some specially modified car.”

The official Nissan response was “ We know several manufacturers have purchased the GT-R for comparison tests. As we do for our customers, we recommend to such manufacturers to, in order to extract maximum performance, follow the recommended break in procedures, inspections and maintenance procedures. Also, we provide driving lessons to GT-R owners and would-be GT-R owners, and are more than happy to accommodate manufacturers in this regard.”

Page 6 – Top – The Carsguide website with the claim by Porsche

Middle – Nissan’s response on the Drive website.

Page 7 – Have we entered a Nurburgring battle period? Pictures of the Corvette ZR1, the Viper ACR, and the stillborn NSX. Sidebar a description of the GT-R “fire truck” used at Nur!

2. Mechanism & Factory

Gearshifts in 0.2 seconds – the 2 pedal transmission.

It is popular now for sports cars to have 2 pedal transmissions, but for the GT-R, a torque converter AT does not makes sense. Everyone wanted a transmission with direct shifting ability – hence just like the F1 cars with superfast paddle shifts, this newly developed dual clutch transmission was installed on the GT-R!

A normal torque converter auto transmission is not worthy of use in the GT-R. New stepless CVT transmissions are not strong enough to handle the power output. Hence the introduction and use of the dual clutch transmission. 1, 3, and 5th gears are serviced by one clutch, and 2, 4, and 6 gear by the other. Hence if in 3rd gear, the other clutch already has 4th gear engaged, providing for a seamless transfer of power and acceleration. This idea has been around for a while, but only with the recent advent of electronic throttle control devices and other electronic controls was it possible to mass produce this kind of transmission.

Also noteworthy is not just the dual clutch, but how fast the shift speed is – 0.2 seconds – this is how long it takes between the time the driver selects the gear and when the power reaches the rear wheels, which are driven by a 1.5 way mechanical LSD.

3. Racing Legend

So coming off the Kondo Racing win at the season opener, the second race was at the newly revamped Suzuka Circuit. The circuit boasted a new pit building, and the East Course had undergone refinishing of the tarmac – but not the West Course. This mean that, for the race the track condition would have two very different mu levels, even though the course layout was no different than usual.

The #1 Motul car was able to qualify in second place, on the starting grid behind one of the Lexus SC430s, and when the race started, grabbed the top spot under Motoyama, and continued to open the gap after the driver change with Benoit Treluyer. Although it seemed victory was assured, bad luck struck, with the car struggling and losing grip, finishing 4th behind the 2 Lexus SC430s and the #12 Impul GT-R. However, a penalty for touching one of the Lexus during the checker flag meant an official score of 11th place. The #12 car finished in 3rd place, and the #3 Hasemi Tomica car crashed out at the very end. The #24 Kondo car finished in 8th place.

4. How to Build

Engine Parts

Mizuno quote – The GT-R has independent left/right intake and exhaust systems. It is a system where the intake system breathes for the opposite side bank.

Note: No history

Next week: Rear Diffuser