Lamborghini Huracan is a sight to behold
But how does it measure up to new 650S?
If you were just perusing spec sheets, you might think the new 2015 Lamborghini Huracan LP 6104, unveiled at this year’s Geneva Motor Show, and McLaren’s equally new 650S shared a commonality of construction.
Indeed, I’m looking at the 610-horsepower Lamborghini’s data sheet right now and it describes the Huracan’s frame as a hybrid of carbon fibre and aluminum which, if you’ve ever seen a naked McLaren, pretty much describes the 650S as well. In other words, they must be similar.
In fact, the two share almost nothing in common, almost as different as a traditional truck with its body-on-frame construction and a thoroughly modern crossover SUV with its car-like unibody chassis.
The McLaren brings modern Formula One technology to street cars, its entire passenger compartment essentially one giant carbon-fibre “tub” providing a cocoon-like shell for the cabin.
To the front and rear firewalls, massive aluminum girders that project forwards and back are attached providing the subframes for engine and suspension. Visually, it is simplicity itself, though, as McLaren engineers are wont to explain, complex to execute.
The Huracan, meanwhile, is a space frame, its entire framework an exoskeleton not unlike your everyday Camry’s unibody and strikingly similar to the framework of an Audi R8. But here’s where the Lambo gets some ingenious technology where even McLaren has so far feared to tread.
The English marque keeps its materials separate; the tub is constructed completely of carbon fibre, the subframe of aluminum, and the two only meet when the two structures are bolted together.
Lamborghini, on the other hand, takes the much more difficult route of mixing the two materials in one structure. Indeed, the cabin’s exoskeleton is a mélange of manmade carbon fibre and smelted aluminum. The rear firewall and the main floor are a carbon fibre weave while the front bulkhead and the side sills are lighter-than-steel metal.
The difficulty, says Maurizio Reggiani, director of Lamborghini’s research and development department, is getting them bonded together in such harmony that they act as one big homogeneous chassis.
Such a seemingly minute detail was not without its challenges: Lamborghini worked closely with Boeing since the airline manufacturer was a little ahead of the auto industry in the melding of metal and fibre into one giant superstructure thanks to its development of the Dreamliner. The trick, says Reggiani, is to optimize where rigidity is needed (torsionally) and where some flexibility is better suited (crush zones) and then getting the two disparate materials to work as one. To do this, Lamborghini had to develop a new process that sees the two materials bonded together via a precisely cured glue.
Eagle eyes will spot that the various parts are also held together by rivets, but, says Reggiani, that’s just to hold the bits in exactly the right position so precisely the desired amount of bonding agent is introduced between the two. After the glue dries, the rivets offer no structural benefit at all.
McLaren will tell you that its purely carbon fibre tub is stiffer than Lamborghini’s aluminum-and-carbon space frame.
It may, in fact, be true. But Lambo’s Reggiani claims that beyond a certain point, additional stiffness is, at best, wasted and, at worst, detrimental.
Besides, he says that the Huracan’s chassis has a stiffness rated over 30,000 Newton-metres per degree (the amount of force required to twist the entire body one degree) and anything above 20,000 is exemplary.
Of course, who is right about all of this chassis mumbo-jumbo is all a matter of conjecture since no independent autojournalist has driven either the 650S or the Huracan.
However, Driving plans to rectify precisely that within the next two months as we’re scheduled to test both new supercars in short order. And then, perhaps we’ll be able discuss whether Reggiani was right on his torsional rigidity calculus.