From SAE: McLaren debuts new entry-level Sports Series
McLaren debuts new entry-level Sports Series
Source: Automotive Engineering Magazine
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The McLaren 570S boasts an impressively low 2895-lb curb weight thanks to its carbon fiber chassis and aluminum bodywork.
McLaren Automotive debuted a new entry-level model for its family of super sports cars at the 2015 New York Auto International Show, with the 570S introducing a new carbon-fiber monocoque chassis for the company that has larger door openings for more convenient ingress and egress.
The 570S is the first member of a product line McLaren brands its Sports Series, which represents an entry level alongside the company’s existing Super Series and Ultimate Series models. These represent a hierarchy in the company’s line, demonstrating seriousness of sporting intent and price.
Of course, practical larger openings compromise rigidity, so the chassis is reinforced with some additional material to preserve its integrity. Even with that strengthening, the bare monocoque weighs only 80 kg (176 lb), while it is a claimed 25% stiffer than competitors’ aluminum chassis.
The 570S’s doorsills are 80 mm (3.1 in) lower than on the company’s earlier models, and are also thinner, for a less cumbersome entry in and out. The car can be equipped to weigh as little as 1313 kg (2895 lb), which McLaren says is 150 kg (331 lb) less than its lightest competitor. The 570S also has thinner B-pillars for improved visibility.
“For the Sports Series we wanted to offer a real sports car feel,” explained Chief Test Driver Chris Goodwin. “Ultimately, it means a car then feels nimble, agile, and it must also possess a lightness and directness of response to drivers’ inputs. Certainly for us, a sports car really needs to engage the driver at any speed.”
Naturally, tires contribute significantly to that mission. For the 570S, McLaren’s goal was to provide useable performance with approachable limits, rather than maximum performance with a precipitous drop-off beyond the limits. To that end, Pirelli partnered with McLaren to tune the 570S’s P Zero Corsas with driver-friendly characteristics.
“We have worked closely with Pirelli throughout the program to design a bespoke tire to best suit the Sports Series, and it is a really important partnership,” Goodwin noted. “Being the only contact with the road, the tire is critical to how the car handles and behaves, and we treat them in the same way as any key suspension component,” he added. “They are specially tuned and developed with Pirelli, and that makes a huge difference to the dynamics of this car.”
Tire sizes are 225/35 R19 on the front and 285/35 R20 on the rear. Regular P Zero tires are a no-cost option for drivers seeking longer tire life and softer ride, while the standard P Zero Corsa’s stiffer sidewalls and grippier tread boosts acceleration, braking, and lateral acceleration for improved track times. The tires mount on 19-inch front wheels and 20-inch rears.
Beneath the engine cover, McLaren’s new M838TE 3.8-L twin-turbo V8 engine is similarly revised, with 30% new components compared to the M838T. It is now rated at 570 PS (562 hp/419 kW) as referenced in the car’s name and 600 N·m (443 lb·ft). It propels the car to 100 km/h (62 mph) from rest in just 3.2 s and to 200 km/h (124 mph) in 9.5 s. Terminal velocity is 204 mph (328 km/h).
The changes to the engine include installation of an automatic engine stop/start system for improved fuel efficiency that produces 25.2 mpg on the combined European driving cycle and 258 g/km of CO2. The car will escape U.S. gas guzzler taxes.
New 60-degree cam-phase controllers reduce internal engine inertia and improve control, which helps both efficiency and throttle response. New equal-length stainless steel exhaust manifolds are mated to hydroformed steel tubes to optimize exhaust flow while enhancing the car’s engine note.
As in previous models, the engine continues to be fitted with a dry-sump oil system and a flat-plane crankshaft. The 570S carries over the same seven-speed dual-clutch transmission seen on the 650S.
McLaren’s programmers have been busy improving the company’s software, so the 570S enjoys new anti-lock brake software that provides better brake pedal feel and reduces the pulsing the driver feels through the pedal when the ABS is active.
New electronic stability control, developed in conjunction with hardware supplier Bosch, adds a Dynamic mode for reduced computer interference with the driver to permit increased ability to slide the rear of the car in a drift while the ESC is active.
For the first time, the ESC system has its own control switch, so drivers can independently set its mode; full, dynamic, or off. Bosch upgraded the pump and dual-valve system for increased resolution so that the 570S enjoys more precise, progressive ESC engagement for less intrusion.
The traction control is also reprogrammed, with more precise control in extreme situations such as drifting. It may be rare for owners to exploit these new capabilities, but they should contribute to some spectacular Internet videos.
Author: Dan Carney
http://articles.sae.org/14036/
