A twist of the tail

McLaren's F1 GTR was the car to beat in GT racing in 1995 and early '96. Then along came Porsche's 911 GT1. Responding with a new, longer tail, the F1 GTR is fighting back. Designer Gordon Murray spoke to Gary Watkins

Ask Gordon Murray who was responsible for the lines of the latest incarnation of his McLaren supercar, and you get a simple answer: "The wind-tunnel." There's little room, he explains, for styling niceties when your target is Porsche's 911 GT1, the first of a new generation of GT racer which swept the McLaren F1 GTR aside in the Le Mans 24 Hours and then in a handful outings in last year's Global Endurance GT Series.

The new Porsche certainly appeared to have spent more time in the wind tunnel than on the stylists' drawing board: witness its expansive whale tail stretching more than a metre beyond the rear wheels; and a long and bulbous nose that proved particularly prone to kerb damage on the car's debut at Le Mans. Designed specifically to go racing, the Porsche had what Murray describes as a massive aerodynamic advantage when it went head-to-head with the McLaren for the first time in the French enduro. "We realised that with the F1 which is based on a genuine road car and the body overhangs that we were stuck with, there was no way we could cope with the 911 GT1."

Ever the pragmatist, Murray cast away the svelte lines of the first McLaren road car without a tear. "I still love the original F1," he says, but this car has been done for a different reason it's a simple question of making downforce." The result is an FIA GT Championship (the successor of the Global series) contender that has grown in length by over 600mm mostly at the rear and gained the prefix "long-tail" at the hand of the press.

Murray, though, makes no apologies for a car that might be called ungainly, a term its creator uses to describe the Porsche. "Overhang equals efficiency." he explains. "Downforce increases without any rise in drag because of the extra leverage of having the wing further back. That's why every time they try to slow down F1 cars, they move the rear wing forward a few centimetres."

Murray won't go into detail on how much downforce the '97 McLaren F1 GTR has gained over its short-tailed predecessor, but the drivers who have been called up to test the first chassis all agree that it's more of a racing car, another step towards the Group C sports-prototypes that died out in the early 1990s. The car is lighter and wider and there's a new six-speed sequential gearbox, but talk to the sportscar aces who have tried the car in testing in Spain and Argentina, the likes of McLaren stalwarts John Nielsen, David Brabham and Pierre-Henri Raphanel, and they speak about the extra downforce first and foremost.

The changes to the rest of the car were claims Murray, already long in place before the Porsche changed the course of GT racing when it made its first public testing appearance at Paul Ricard last March. "We always thought that the '97 car would be the final version of the F1 GTR." he says. "When we did the first GTR in 1995, we promised stability for two years, so that our customers wouldn't have to buy new cars.

"But we always intended to put in a proper racing gearbox and get rid of a lot of components left over from the road car. But when we saw the Porsche we had to go for a new body," says Murray, before stopping and correcting himself. "Not a new body, but a modification of the body to make better use of the regulations."

When talking to Murray, lump the McLaren together with the Porsche and the Lotus GT1, built around the aluminium monocoque from the Elise sportscar, at your peril. "That hurts a bit," he says. "The press talk about new cars such as the longtailed McLaren and the Porsche 911 GT1, but that's a pretty heavy misconception. Our road car was there in 1992 and we've done a bodywork modification in reaction to Porsche. The basic concept of the car hasn't changed. In principle, it's still an F1. We haven't said forget that monocoque, we'll have racing suspension geometry and do everything from scratch and build a racing car, and say 'by the way we might make a couple of road cars'." The last comment is an obvious swipe at Porsche and Lotus, whose latest GT contenders were conceived as race cars first and foremost.

"When the rumours started that we were doing the same thing as Porsche and building a new car, down at McLaren we were having a little laugh. Because even if we'd wanted to we didn't have the budget or the time to do a completely new racing car and to build a completely new road car and then type approve it, all before the first race."

However, McLaren is having to build long-tailed road cars and win type approval, as demanded by the GT racing rulemakers, because under European Community rules the '97 F1 is described as a "variant". That means McLaren is going through the process of proving that the longer F1 is a bona fide car for the road, including minutiae such as brochures and service manuals. And to help ensure that McLaren sells at least a handful of long-tail F1 road cars, dubbed the GT, it has been given a more luxurious interior and an extensive options list to make it attractive to collectors.

But the '97 F1 GTR isn't just a new body on an existing car. A lot of detail work aimed at reducing the weight of the car and making it more user-friendly means the car is "90% new", according to Murray. While the original F1 GTR weighed in at over 1100kg, '96-spec cars rolled out of the factory at 1020kg, and Murray has aimed for a similar drop for '97 customer cars, although he won't say if the factory test car hit his 950kg target.

Another target was making the F1 GTR an easier car on which to work, admitting that about a third of the design team's effort has been focused on this task. "We've looked at the accessibility of the major components, and engine and gearbox changes should take less time now the bodywork can be unclipped and removed very quickly." It had to be unbolted on the earlier versions.

The move away from the original car's synchromesh gearbox, modified from the road car unit, to a pure-race sequential gearbox was also high on Murray's job list for the '97 car. While up to the job of a four-hour race, a new 'box was required to get a McLaren to the end of the Le Mans 24 Hours witness the fact that six out of the seven F1 GTRs entered in last year's edition of the sporstscar classic hit transmission problems during the race.

For a few months last summer the possibility existed of another major revision to the F1 GTR an engine transplant. The glorious V12 designed and built bespoke for McLaren by BMW could have been a victim of engine rules designed to peg back the performance advantage enjoyed by the F1 GTR in 1995 when it had been beaten only twice from 13 starts. Murray estimates that the venerable twin-turbo V8 Ferrari F40, in the guise of a GT-Evoluzione homologation special, had a power advantage of nearly 50bhp last season. Had the size of the power-limiting air-restrictors not been changed in the favour of normally-aspirated engines such as the BMW V12, Murray says McLaren and its German engine supplier would have had no choice but to follow the lead set by Ferrari with its V8 and Porsche with its flat-six.

A turbo version of BMW's four-litre V8 was built, says Murray, as a safeguard. "If they hadn't changed the rules, we'd have had no choice but to swap to the turbo. If the F40 could run away from us at two seconds a lap on the faster circuits, then imagine how much faster the new Porsche could have been if it hadn't been sandbagging."

However, McLaren never had to cash in its insurance policy - it's claimed that the V8 never even ran on the test bed. Air-restrictor sizes have been changed for FIA series, re-establishing what Murray describes as a "fair playing field", even if McLaren's rivals claim to the contrary.

Despite claims from Porsche and Lotus that the new engine rules have rendered their cars uncompetitive, Murray is under no illusions of the size of the task faced by McLaren's factory representatives, the Schnitzer and GTC teams in what threatens to be a classic year of GT sportscar racing. Porsche and Lotus should have the edge, he reckons, because they are "hybrid cars designed to go racing. And, if they've got their sums right, they should be faster than us."