http://www.roadandtrack.com/motorsports/a24903/nissan-gt-r-lm-nismo-tech-deep-dive-with-ben-bowlby/
Nissan GT-R LM NISMO: A deep dive with Ben Bowlby
To better understand Nissan's radical new race car, we sat down with its creator.
Road & Track Marshall Pruett
You'll need to embrace a mashup of letters and numbers to digest the insanity housed within Ben Bowlby's 6-foot-wide by 15-foot-long Nissan creation.
It's an LMP1. And not just a normal LMP1, but an LMP1-H. The H is for Hybrid. It conforms to the rules created by the ACO, the French sanctioning body that runs the LM24, aka, the Le Mans 24 hours, and will race there and at the rest of the WEC (World Endurance Championship) governed by the FIA.
It's FWD in terms of which end the IC—internal combustion—engine sends its power. It's designed to be AWD, thanks to the H propelling the front and rear wheels. It's a TTV6—a twin-turbo V6, with DI—direct-injection. And its 3.0-liter engine was not, as some have suggested, originally envisioned as an F1—sorry, Formula 1—powerplant.
It was originally targeted to have 2000 horsepower, but that figure has been tamed to something in the 1250-1500 region, with the IC contributing just over 500 hp and the hopefully 8MJ H Flybrid system offering up the other 750-plus hp.
Put it all together and we have an ACO LMP1-H that's FWD, AWD, featuring a 3.0-liter DI TTV6 with an 8MJ H, dubbed the GT-R LM NISMO, that will race in the FIA WEC.
And, it was created to deliver a giant FU to the competition. How's that for originality?
The last time racing cars sent my imagination wandering into truly uncharted territories, it was done by vehicles dreamt up by Jim Hall's team and Dan Gurney merry band of All-American Racers. For current and future generations of techno-dreamers, I'm willing to bet Ben Bowlby's Nissan GT-R LM NISMO LMP1 will be their Chaparral 2J "sucker car" or AAR Eagle Mk III.
The mad Englishman's latest work grabs the state-of-the-art LMP1 concept, holds it firmly in place, draws a new line, and distances itself from anything Audi, Porsche, or Toyota conceived through the 2014 World Endurance Championship season.
The front-engine design immediately sets Nissan apart from the rest of its LMP1-H competitors—and every other prototype we've seen in at least a decade.
You can say the GT-R LM NISMO takes after 1997's front-engined Panoz Esperante GTR-1, but then you'd have to say the Panoz takes after Bob Riley's 1983 Ford Mustang GTP, which featured a ferocious front-mounted 2.1-liter 4-cylinder turbo, and the lineage continues back through time. What you won't find is a predominantly FWD front-engined prototype that uses the entire body—inside and out—as an aerodynamic weapon. Nissan, Bowlby, and the entire NISMO design team own that narrative with complete authority.
Speaking with Bowlby on his free-spirited GT-R LM NISMO, I started by asking him where it ranked among decades of open-wheel and sports-car designs that have come from his hands.
"Well, it's definitely the bravest that I have been," he said. "It's definitely the boldest undertaking. It's definitely the least comfortable that I have been in putting so many bits of what I have learned over the years together. Normally, the regulations don't permit you to try and put together such an integrated design.
"In this particular instance, the FIA WEC and ACO's regulations give you an incredible breadth of opportunity. The fact that you can effectively make a four-wheel drive car that you don't have to put the engine on one end or the other. The fact that you can truly look at aerodynamic efficiency and fuel consumption efficiency, or lap specific fuel consumption; play a game of what is the most intelligent way of solving the problem of getting around Le Mans the fastest way over 24 hours."
Nissan have joined the other LMP1-H manufacturers in the pursuit of achieving the maximum 8 MJ KERS harvesting and release, and like their rivals, it's a goal more than a guarantee. The GT-R LM NISMO uses a custom KERs unit supplied by Torotrak, better known as Flybrid to those who've seen the mechanical systems recently used in other prototypes.
The device is mounted beneath the keel—just under the driver's legs—and is driven by the 5-speed transmission that sits in front of the engine. It returns its energy to the front wheels through the same shaft that runs through the V6's 60-degree engine V, and can send the rest, if the team decides to use AWD, to the rear through a long driveshaft beneath the tub that connects to a differential which then feeds the rear wheels through a complex system of secondary driveshafts and outboard gearboxes.
With plenty of engine power and the potential for monster hybrid power, a delicate balance of KERS usage is timed to hit once the GT-R LM NISMO exits a corner and achieves something in the range of 70 mph. With everything available at once, the Nissan would spend each lap putting on billowing FWD dragster burnouts in every turn.
"There are lots of things that the engine recovery regulations provide as an opportunity," Bowlby noted. "They come with a big price from many respects. To recoverand deploy 8 MJ is expensive. It's very time-consuming in the design because there isn't such a thing as a 8 MJ system that just sits there on the shelf. And it is expensive from a weight standpoint. And it's expensive from a reliability standpoint. If you have an 8 MJ system that fails during Le Mans, you're going to lose over 7 seconds a lap. You can't do much about it, except peeling the car apart and changing it out. Basically, it is a very big burden on reliability and lap time for 24 hours.
"Audi, once again, won Le Mans in'14, and did it with a 2 MJ system. Sometimes we have heard the Audi system wasn't working at all and you could hardly tell in lap time terms because if you lose a 2 MJ system it is actually only 1.6 seconds a lap, by our estimation. Anyway, it's a very interesting opportunity, it's like a dangling carrot because every megajoule is worth about a half a second a lap as you add it. Our job is to grab that, as a manufacturer. Of course, that is why the Toyotas and Porsches should have been, all things being equal, 2 seconds a lap faster than the Audi with their 6 MJ systems. It's impressive that the Audi wasn't 2 seconds a lap off the pace, given they were a 2 MJ car."
Hybrid power unit design is, arguably, the one great frontier LMP1 manufacturers continue to explore. As Bowlby said, off-the-shelf solutions do not exist for the upper 6-8 MJ limits, and for that reason, we've seen every LMP1-H constructor adjust their stated use of hybrid power after aiming high and settling for something lower. We know Nissan wants 8 MJ—they'd use 80 MJ if it was allowed and feasible—but we'll have to wait until the GT-R LM NISMO turns up for its first race to know whether it has 8MJ, or if the system will even be on the car. Such is the state of development in LMP1-H…
Turning back to the GT-R LM NISMO's conventional power source, the tiny, barely-there twin-turbo V6 is easily lost amid the maze of wires, pipes and support systems contained around the Cosworth-based mill. Asking NISMO boss Darren Cox to confirm the engine's origins was met with an expected answer: It's a Nissan.
To be fair, Nissan commissioned it, paid for it, and has the right to call it whatever they want.
"We selected over a very long period of time in great detail the best solution, not only doing bore and stroke configuration but also the whole of the charging and cylinder pressure, influence on drivetrain and so on," Bowlby explained. "It is an even-firing V6, smooth-running V6, smooth-running, low vibration. It's a lovely engine; it's a very nice piece. That was where the project started, in a way. That was the first piece that started to come together, other than the concept. It's a fantastic engine.
"The engine is 100 percent designed for this particular challenge. It has not got any… it's not an F1 engine that turned into a sports car engine or an IndyCar engine that turned into a sports-car engine. This is from the ground up. How do you best solve the challenge of making a gasoline engine, to the regulations to be successful at Le Mans? It's with a clean sheet of paper design. And it was designed around the layout of the car and the aerodynamics, the weight distribution, and so on. It's an engine that was truly designed for this car, nothing else."
With its front-engine design, big KERS ambitions, and the flexibility to use FWD with the V6 along, FWD with the V6 and KERS, or AWD with KERS powering the rear, the GT-R LM NISMO is loaded with options.
Moving away from its drivetrain, which will surely draw the most attention from fans and media outlets, the biggest breakthrough with Bowlby's Nissan is the through-flow aerodynamics. Your conventional rear-engined LMP1-H chassis is limited for space at the back of the car, and as a result, large, volume-robbing items like the radiators and other auxiliary systems are moved forward where they're housed in the sidepods.
With air hitting the front of the GT-R LM NISMO, it envelops the car—flows beneath the car via the splitter, and heads over and around the body. By moving the engine and all of its friends to the front, Bowlby was able to create a pair of rectangular tunnels that take their feed from the trailing edge of the splitter's upswept wing profile and carries large volumes of air around the cockpit and out the highly tapered tail section.
It's similar to a catamaran design where the center portion of the car—the one that punches a big, disturbing whole through the air—has been taken away to allow the air to pass through the area with ease. By using the empty side pods as a bypass, Bowlby has significantly reduced aerodynamic drag, and in Nissan's quest to win through innovation, this core design element should produce improved fuel economy, among other benefits.
"That is the complexity of the regulations, or the interest in the regulations, and why we turned the car on its head, because we wanted to produce an aerodynamically efficient car," said Bowlby. "It is very simple. Rather than have to take the air that comes underneath the splitter and force it to take a longer path down the outside of the car by venting it behind the front wheels, then blending it into the air flow down the side of the car and basically pushing it out that way—which makes the car seem wider and less efficient.
"We gave it an easier path so the air comes underneath the splitter and comes out above the diffuser. It is a more optimized path. And before everybody jumps on the great idea of how cool that would be to do, just try doing it!"
At approximately 15 feet in length, you can stand at the back of the Nissan, and when the lighting is just right, see all the way through the tunnels and spot the front suspension. Crouch down and take a closer look, and you'll notice the tub tapers inward starting just below the cockpit openings. Referring back to marine concepts, it does bear a resemblance to a high-performance hull, and in this case, Bowlby has done all he can to make the bottom half of the tub less of a slab-sided creation and more like a"V" to increase the volume of air passing through the built-in tunnels.
As I mentioned in
my behind-the-scenes story, seeing the GT-R LM NISMO run in the wet at Circuit of The Americas, and the interaction between the spray and the Nissan's through-flow aerodynamics, was unlike anything I'd witnessed with other LMP1-H creations.
Nissan's new 2015 GT-R LM NISMO LMP1 is captured at Circuit of The Americas by Marshall Pruett on 12/17/2014 during the filming of Nissan's Super Bowl ad.
On track, the choice of a turbocharged FWD layout invited the GT-R LM NISMO into the same torque-steer problems I first encountered driving Saab turbos in the 1980s. As the front tires change direction, feeding power to the ground is a complex task, and as Bowlby explains, they went into the Nissan's design with the problem in mind.
"As a four-wheel-drive car you can deploy much more power than you can with a two-wheel drive, obviously," he remarked. "It's the fundamental physics of a front-wheel-drive to limit the traction capability. However, the regulations have a specific requirement for Le Mans that a 550 or so horsepower front-wheel-drive layout with an adequate degree of aerodynamic downforce can overcome the problem. You can do the simulations and you will find that.
"Handling the torque steer is mostly about having a balanced torque distribution of both front tires. We have equal-length driveshafts and a carefully refined geometry of the suspension, uprights, steering, and so on. Torque steer in itself does not seem to be an issue from laying down 550 hp or so."
Managing the mayhem that KERS power can add to the front wheels is the next step in mitigating the effects of torque steer.
"The energy recovery system deployment typically does not want to take place when you are limited in anyway by the amount of power that the gasoline engine can put down," Bowlby continued. "In other words, you don't want to be adding recovered energyto a traction-limited internal combustion engine. You're going to throw the deployment down once you are not internal combustion engine traction limited. It comes afterwards. That means that, in fact, you're going to deploy the energy from a reasonably high speed, at which point we are already rapidly increasing in downforce. It obviously goes up by the square of velocity.
"So we find that we can quite quickly lay down really quite a lot more power. We don't need it coming out of the corner at the beginning of the exit of the corner, but once we are on the straight and we have built up a certain amount of speed we can quickly accelerate the car.
"And an interesting feature, horsepower being a function of torque and RPM or speed, means that we aren't actually talking about a ferocious level of torque. We're talking about quite a lot of power but at quite a high speed. So the torque on the tire contact patch is not particularly outrageous. We will be challenged by our front tires, and to balance the challenge of the rears we've made the rears smaller."
Fast forward to the DeltaWing's launch, and the dart-like sports car, which was fabricated at All-American Racers, sported the same tunnels. With an eye for intriguing concepts, Bowlby put Gurney's "BLAT" pieces (Boundary Layer Adhesion Theory) to use on the Nissan-powered DeltaWing, and readily admitted the tunnels became the key aerodynamic aids that make its underfloor produce efficient downforce.
After seeing the GT-R LM NISMO's through-flow aero design, I was taken back to Gurney'sall-conquering Eagle Mk III GTP car and its semi-through-flow ducting. The Nissan was built around the tunnels for the sake of aero efficiency, while the Mk. III, which used bolt-on tunnels beneath the bodywork to feed its rear-mounted radiators, was an addition to the base design.
I wondered: Was Bowlby inspired by the semi-through-flow 1991-1993 Eagle Mk. III when it came time to pen the GT-R LM NISMO?
"I would definitely say it was a factor in the whole of this car's genesis!" he said with pride. "For starts, back to the Eagle Mk. III, that was an absolutely brilliant design.That's fair way to say it. Of its era, it was the best car out there. It was advanced in its aerodynamic performance. I certainly think it was one ofthe first cars to really exploit the dumping of the underflow from the splitter and out behind the front wheels. In order to do that, a duct was created to position the radiators rearwards almost alongside the engine.
"It's quite a few parts to manage but in order to do it, you have to make some other compromises in the packaging. Yes, we have got an awful lot of engine and bits and pieces ducted into a very small space at the front, and that is a challenge that has been created. And it also meant that the rear drivetrain is also made more complex than would be the case if we didn't want to duct the air through there, or you could duct the air and put all the wishbones and suspension and components and drive shaft in the duct, but you would perhaps lose a bit of the advantage that it gave you. If you can do it without that and find a good compromise then it's a good way to go."
We're a few months away from seeing the fleet of GT-R LM NISMOs racing in anger against the LMP1-H establishment. Will it leap to the head of the pack right away? Could its sweeping dedication to innovation extend the learning curve required to find Victory Lane? It's too early to tell, but I'm confident Nissan's bold entry into the top WEC category will produce wins in the marketplace before it reaches Le Mans.
"There was an opportunity to do something different—our own, and Nissan are about being disruptive in the industry, producing value for money, and taking on big challenges," Bowlby said. "That is the marketing, the core values. People will look at the car and say, 'you've got to be joking. You can't be serious, that will never work!' That is why it is interesting and why there are still some dark corners of motorsport that haven't been explored. You say it's all been done before, but actually this configuration, concept and idea has not been done before.
"That is why it is interesting and why there is relevance to where we're going with road cars. The concept of having highly efficient aerodynamics, the concept of some of the technology in the car from the energy recovery standpoint has benefit for future high performance, yet efficient road cars, is why we're here. There are a lot of little pieces to this that are relevant and will change people's perceptions of the technology that Nissan brings to the road in the future. That is really what it is all about."
1
9
