"This is the Zonda F - the third model in the Pagani supercar range, due to be unveiled at the Geneva Motor Show in late February.

The car will be the most powerful Zonda yet, squeezing an awesome 620bhp from its 7.3-litre AMG engine, and will be priced at the same level as the existing Zonda Roadster. Details of the car, plus confirmation of plans for an all-new supercar to follow in 2007, have been revealed to evo by Zonda creator Horacio Pagani in an exclusive interview.

Even though sales of the current Zonda are going well, Pagani feels the time is right to introduce a new ultimate version of his supercar, featuring various aerodynamic tweaks and a heavily revised version of the existing engine. He wants the car to compete squarely with the new generation of supercars - notably the Ferrari Enzo - that have appeared since the C12S was first developed, and 600bhp is considered minimum requirement for joining this exclusive club.

Extensive aerodynamic work using the latest CAD programs has revealed certain deficiencies in the current design that Pagani is keen to rectify. He has particularly identified the need to redesign the rear spoiler and move the position of the rear-view mirrors from the A-pillar to the front wings.

Computer modelling has shown that airflow around the mirrors becomes disturbed at speed, causing turbulent air to flow directly to the twin rear spoilers, reducing the downforce they create. The fact that the rear spoiler was originally designed as two separate wings, with a large gap between them, also reduces the downforce effect.

By moving the mirrors to the front wings and fitting a one-piece spoiler right across the rear, Pagani has found a way of countering this problem. Further tweaks at the rear involve fitting two new wings under the venturi, to help smooth out the flow of air at the rear of the car and reduce the drag at high speeds.

The computer work also revealed a massive low-pressure spot just behind the front wings, which is causing increased drag on the car, as well as lift. This has been corrected on the new Zonda F by the addition of twin NACA vents on the trailing edge of the front wings whose purpose is to vent air from the front-mounted radiator. During all this aero work, Pagani also discovered that the radiator isn't working as efficiently as it could. The computer model showed that once air enters the front radiator intake at the nose of the car, it gets disturbed within the space between the intake and the front of the radiator. The result is very little air flowing through the top of the radiator. On the new car the front intake is much wider, as well as deeper, so the radiator now works to maximum efficiency, which is deemed essential given the massive power increase for the F.

Overall, maximum downforce measured at 320kph (200mph) has gone up from 700kg to 900kg but is much better balanced, front to rear, than before thanks to the big increase in the effectiveness of the rear wing. The drag coefficient has dropped as well, so top speed is expected to rise significantly.

The increase in engine power has come about from a complete re-think of the big V12's induction system. The standard Mercedes system (which will still be used on the 550bhp versions) was designed with a peak power output of


400bhp in mind, so it is operating way beyond its original design parameters. The completely new intake manifold on the 620bhp version improves breathing through the adoption of special oval-shaped ducts that help maximise the size of each individual tract and hence airflow. Combine this with a revised exhaust manifold, together with a complete re-mapping of the engine's ECU, and even Pagani is surprised at the jump in horsepower achieved from these basic tweaks. A new twin-plate clutch has been developed to handle the extra power.

The Zonda F will have the added bonus of weight savings, as the new intake manifold weighs around a third of the original weight of the standard Mercedes item. With other changes being made to the tubular frame around the engine on the new model and a revised use of carbonfibre in certain key areas, the kerb weight has dropped by a minimum of 20kg to 1260kg.

Other changes made on the Zonda F are the fitment of larger wheels (19in front, 20in rear) with 255/35x19 front and 335/30x20 rear Michelin Pilot Sport 2 tyres. The new wheels allow larger, 385mm front discs with six-piston callipers to be squeezed inside the rims. There is now also the option for buyers to fit 380mm carbon-ceramic discs to the car for the first time, available as a 15,000Euro option. These will reduce the kerb weight by an even greater amount. The wheels themselves are forged in one piece, weigh 1.5kg less than the current design and are fitted with titanium wheelnuts.

The existing Zonda C12S and Zonda Roadster will continue to be built in their existing spec alongside the new car when production of the Zonda F starts in the spring.

The F will cost approximately Pounds393,000 (based on current exchange rates), which is identical to the current Zonda Roadster.

Pagani's next project after the introduction of the Zonda F is an all-new car that's slated for launch in 2007, details of which will remain firmly under wraps until nearer the time."

hang on a minute, the AMG V12 was a regular Mercedes V12 tuned to deliver 555hp, surely AMG changed the induction system to cope with the massive increase in power? And now Pagani knows best by fitting a new one thats also a third lighter and can handle 620hp? Is it just me or something's not right.....