PRUETT: Nissan enters big LMP1 development phase

PRUETT: Nissan enters big LMP1 development phase

Le Mans/WEC

PRUETT: Nissan enters big LMP1 development phase

One of the better questions throughout the week at Le Mans in June was how the upstart Nissan Motorsports team should be judged. Taking on sports car juggernauts like Audi, Porsche, and Toyota was always going to be an uphill battle, and Nissan, by comparison, was coming into the LMP1-Hybrid fight with a comparatively modest war chest at its disposal.

Coupled with a late and challenging start to the program, Nissan’s tight budget meant it could not spend its way to achieve a competitive state on its debut, and their ensuing results at La Sarthe were hard to ignore.

Unfortunately, success at Le Mans isn’t judged on one’s performance in relation to the number of asterisks placed next to the entry. Cold, unqualified statistics are recorded, and with Nissan’s numbers at La Sarthe in mind, the Japanese brand left the great 24-hour race humbled and ready to address its shortcomings.

Nissan built a significant list of improvements to produce throughout its pre-event testing program and as race week progressed. Thanks to the friendly post-Le Mans schedule, the team has had more than a month to bring new components online and to redesign some problematic items that were exposed during its first appearance at the famed 8.5-mile French circuit.

The revised GT-R LM NISMO package will test next week at Circuit of The Americas, and despite suggestions to the contrary, Nissan is scheduled to compete at the next World Endurance Championship round at the Nurburgring and at the rest of the events on the WEC calendar. WEC CEO Gerard Neveu also weighed in on the topic of Nissan’s continued presence in the series.

“I have absolutely no worry for Nissan,” Neveu told RACER. “I have already received the confirmation for Nissan for the shipping paperwork and freight and everything for Nurburgring. There are always rumors when there is nothing to say. There is nothing to say just because Nissan are following their own program and they are working very hard on improving the performance of the car. They will be part of the championship until the end of the season.”

THE LIST

Compiling the list of items to increase the GT-R LM NISMO’s reliability and decrease its lap times began the moment it started testing in December and continued through the final lap at Le Mans. As I wrote a few months ago, the Nissan’s competitive capabilities were undermined from the outset by an energy recovery system (ERS) that can only be described as a complete failure.

Supplied by Torotrak, the giant mass of aluminum was meant to deliver 8MJ of ERS boost, yet was plagued by electronic control and mechanical issues from the outset. Unsuccessful attempts to use the system in testing forced Nissan to abandon its ERS plans prior to Le Mans, and as a result, Nissan’s trio of LMP1-Hybrids raced as defacto LMP1-Lights.


 

The absence of ERS boost added at least seven seconds to its projected lap times, yet the best GT-R LM NISMOs qualified more than 16 seconds behind the pole-sitting Porsche 919 Hybrid. Atop the list of fixes, a new ERS vendor with a proven solution was targeted long before the Nissans unloaded for their first race at Le Mans.

If recovering approximately half of the time loss can be achieved with a proper 8MJ ERS system, acquiring the other half is where Nissan’s list begins to grow. The NISMO team will find big chunks of time with a comprehensive rethink on suspension design and robustness, and by detailing the problems below, we’ll arrive at the fixes they need.

WIDEN THE TRACK

With natural concerns over reliability at a punishing circuit like Le Mans, Nissan devised a plan early in the car’s gestation period where it would use advanced aerodynamics, a powerful engine, and 8MJs of ERS to sail around the 8.5-mile course without risking component failures caused by pounding over the curbs.

GT-R LM NISMO drivers duly followed the instructions, but without the 8MJ at their disposal, avoiding the curbs torpedoed any chance of recording decent lap times.

Nissan’s nine-deep driver pool was forced to cautiously drive around the same curbs that other drivers flew over. And with the inability to shorten corners and power over the curbs to lengthen straights, the trio of GT-R LM NISMOs were reduced to treating Le Mans like an endless series of drag races. With approximately half the power its rivals had to deploy, the Nissans appeared to be stuck in neutral as Audis, Porsches, and Toyotas rocketed away under initial acceleration.

Looking at the final complex of corners leading onto the front straight, Nissan drivers were forced to slow more than most prototypes and drive around the curbing at the Ford chicanes. Restricted to using the flat, narrow sections of the track, GT-R LM NISMO pilots were often heard coasting and waiting to get around the chicanes before applying full throttle after exiting the final corner.

The gaps varied, but the GT-R LM NISMOs gave away up to four car lengths on acceleration. It was a laborious process to watch every lap, and on occasion, GT drivers – those who charged through the final chicane – had to dodge the slower Nissans on corner exit.

It’s believed one or more suspension failures also happened with the GT-R LM NISMOs at Le Mans, and with stronger pieces in place for the ‘Ring and beyond, Nissan drivers should be able to use the curbs and gain time on every lap.

WHEEL RATES

Reliability concerns formed part of Nissan’s strategy to avoid the curbs at all costs, but there was actually a second and much bigger issue that kept the GT-R LM NISMOs tucked neatly between the chicanes.

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The problem was revealed when Nissan drivers mistakenly drove over a section of curbing, and caused one of the most curious chassis reactions I’ve seen in 30 years of competition.

With a significant forward weight bias and skinny rear tires, curb hopping was always going to expose control issues for the GT-R LM NISMOs. Launching the front of the prototype over a chicane would lead to all of that front-engine mass slamming down upon landing, and with narrow rear tires doing very little to help settle the chassis, it created an effect where the nose was driven into the pavement while the rear of the car lifted off the ground – a reverse wheelie, in simple terms.

Spotting a Nissan driver who used the curbs was easy at the Ford chicanes – they were the ones entering the front straight understeering toward the gravel trap with the rear tires dangling in the air.

And the reason for the GT-R LM NISMO’s “chicane problems” goes even deeper than its front-heavy/rear-light chassis layout.

On my first glance at the car just before chrismas, I was drawn to the front suspension geometry and specifically, the high wheel rate from the interaction between the suspension pull rods and rocker arms. Without going into a boring technical explanation, the Nissans feature a front suspension arrangement that requires exceptional force to compress its shocks and springs.

That built-in layout meant that even with the use of soft springs and damping, hitting a curb would send the front of the GT-R LM NISMOs skyward instead of absorbing the hit and keeping the chassis level and composed.

2015LeMans24 MarshallPruett Sat613 1517I watched in amazement at the top of the front straight (LEFT) during the race when the No. 22 Nissan drove up, turned left into the first Dunlop chicane and used some of the inside curbing, which then launched the front into the air.

Because the car was turning left and going uphill, it landed with the right-front tire first, and with all of its weight hurled onto one corner, it struck the ground like a gavel being cracked on a table. Once the right-front was done compressing, it rebounded and sent forces diagonally to the left-rear.

Due to the narrow rear tires, there wasn’t enough contact patch to stabilize the car, and from there, I watched as the right-rear came back to earth and, with crazy, uncontrolled oscillations to deal with, the rear tires pogoed up and down–like someone running in place.

The GT-R LM NISMO chassis rocked left and right as its driver waited for the tremors to stop. Each pogo action was less and less severe as the No. 22 regained its composure. 


Viewed head-on, it looked like the Nissan was possessed, and the ride could not have been pleasant from inside the car. The tilt-a-whirl action only lasted a second or two, but when it was done, the GT-R LM NISMO had blown past its turn-in point to crest the hill. Beyond looking crazy, the light use of curbing also cost the No. 22 a lot of time.

With a softer wheel rate, Nissan drivers will be able to use curbing and avoid the bucking bronco routine. The narrow rear tires are part of the GT-R LM NISMO basic design, which makes going to a wider footprint to help with cornering stability highly unlikely. A Formula 1-style FRIC system will help Nissan to connect its front and rear suspension hydraulically, and with that update, the freaky pogoing should be significantly reduced.

Stronger suspension with more compliant front geometry will transform the GT-R LM NISMOs into cars that can, for the first time, link the corners and straights together in one continuous movement. Having seen the other LMP1-Hybrids set the standard for flowing, unrelenting speed, Nissan now knows what it needs in the handling department to join the party at the front of the grid.

NEW POWER GENERATION

It’s premature to confirm the system, but it wouldn’t be a surprise to see the 2016 GT-R LM NISMOs fitted with same style of battery-based A123 ERS system Porsche used to win Le Mans. A123’s customer-driven ERS solutions can be tailored to the needs of Nissan designer Ben Bowlby, and should put the cars in the performance window that was expected when the project began.

As obvious as it might be, a functioning ERS system will give Nissan more than just extra acceleration leaving the corners. The car’s original performance spec was fashioned around an 8MJ system, and with braking assistance expected from the unit during heavy ERS harvesting, Nissan scaled its brake system down accordingly. They tried running with the lesser 2MJ output produced by Torotrak (BELOW), and thanks to the minimal harvesting it required, the GT-R LM NISMO’s brakes were immediately overtaxed.

Bigger, heavier brakes were soon fitted, and the extra heft and mass at each corner further increased Nissan’s lap times. Not only did the loss of ERS add heaps of time on the long Le Mans straights; time was also surrendered under braking as the heavier GT-R LM NISMOs were unable to go as late or deep as its rivals.2015AudiP1SebringTestPruett 017

The Nissans will contest the rest of the 2015 WEC championship without ERS, leaving its 3.0-liter twin-turbo V6 to handle all aspects of acceleration without providing significant help under braking. Having declared the GT-R LM NISMO as a LMP1-H with the ACO and FIA this season, temporarily moving down to LMP1-L is not an option.

Another loss from running without ERS comes in the fuel flow restriction imposed by the ACO/FIA. Every LMP1-H car spends a portion of each lap lifting and coasting to stay within the maximum fuel-per-lap allocation, and with ERS handling portions of each car’s acceleration, its combustion engine consumes less fuel.

Minus ERS, Nissan’s cars burned more fuel powering out of each corner and they were forced to pay a higher price by spending more time lifting and coasting to stay within the rules. Without ERS, the LMP1-H Nissans suffer in every way possible.

UNTAPPED POTENTIAL

It’s easy to blame Nissan for the GT-R LM NISMO’s shortcomings, but I’m not sure it’s entirely warranted. Referring back to their limited budget, Nissan’s design team swung for the fences, missed badly with a few directions and one vendor choice, and is taking a second stab at meeting their objectives. Every manufacturer runs aground at some point with an adventurous concept, and the fact that Nissan ended up on the rocks right out of the gate doesn’t mean they can’t recover.

Frankly, with three fully developed, race-winning LMP1-Hybrids to set the standard, I’m thankful we have Nissan’s alternate approach to follow. Granted, there’s a finite window for the program to move from being quirky and fun to a legitimate contender, and while it’s in the former phase, tracking the GT-R LM NISMO’s development should be quite interesting. Talking about a massive gap to the leaders after Le Mans 2016 isn’t an option; no one will care about third or fourth attempts to tackle the LMP1-H establishment.

Part of the upcoming test at COTA will see the Nissan’s high-downforce bodywork pressed into service as the WEC moves to tracks where ultra slippery aero is a liability. If there’s one area where the GT-R LM NISMOs clearly succeeded at Le Mans, it was with Bowlby’s through-flow aerodynamics. Running as a 0MJ car class clearly hurt the car under acceleration out of the corners, which made its straightline speed damn impressive. 

The Nissans vied for top speed honors at Le Mans, and even with a 16-second gap to the pole-winning time, they managed a best of 337.0 kph/209.4 mph to the 341.3 kph/212.0 mph posted by Audi while recording their best qualifying time. It’s a small concession, knowing how much speed Nissan is searching for, but also serves as a reminder that the GT-R LM NISMO concept is worth developing to a point where its full potential is shown.

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