When an automaker designs a mid- or rear-engined car, it needs to figure out how to direct cool air to the engine without an open frontal area. McLaren F1 designer Gordon Murray was well aware of this problem. The roof scoop that is a hallmark of the legendary supercar's design channels high-pressure air into the engine for a mild charge effect. According to Murray, McLaren had a hell of a job making it work in normal street driving conditions. "We had to design a water separator, trap and drain to avoid filling the engine with water when following a truck in the rain," .
Perhaps that's why you don't see roof-top air tunnels on most road cars. But in racing, cool intake air is crucially important. So let's take a look at some of our favorite above-the-roof air intake tunnels.
For Abarth, it all started with Fiat's 1972 X1/20 project, which eventually turned into the Lancia Montecarlo. Pininfarina was commissioned to create a design study using Abarth's new chassis for the 1974 Turin Motor Show. But the Abarth team ran another project in parallel, hoping to replace the 124 Spider with the Bertone-designed X1/9 as Fiat's rally racing contender.
Fiat chose the 131, which Abarth then turned into a triple world champion.
Powered by a Fiat twin-cam bored from 1600 to 1840cc with a 16-valve cylinder head and twin Weber carburetors, the remaining X1/9 Prototipos saw limited racing service. And since body shells and parts were swapped at random, production figures are hard to accurately estimate. A safe guess says five of these vehicles were built.
The story of Fiat's original commission is a tad more colorful. Known first as the Abarth SE 030, the Pininfarina-styled project was powered by the Fiat 130's 3.2-liter V6, tweaked and fed generously by Abarth to produce around 280 horsepower. The power went through a ZF gearbox and differential, the same used in the De Tomaso Pantera. The car made its racing debut in 1974, and almost caught up with the Lancia Stratos Turbo straightaway.
But what was displayed as the Fiat Abarth 030 at the Turin Show was soon cancelled by Fiat, only to continue development as the Montecarlo over at Lancia. Aimed as a luxury alternative to the Fiat X1/9, the Montecarlo then spawned the amazing Group 5 Beta Montecarlo Turbo for the 1979 season. And Abarth couldn't be stopped.
The Group 5 Montecarlo evolved into what became the Lancia-Abarth Rally 037, which in 1983, ended up being the last rear-wheel drive car to win the World Rally Championship—despite not using the wild rooftop air intake from its predecessor, the Abarth SE 030.
And who else but Honda's works racing team could bring back such a radical design feature?
The first-generation NSX stayed in production for a whopping 15 years, and even after the last one left Honda's Suzuka research and design facility in 2005, the motorsport teams kept racing them for another four seasons. And for the 2008 Tokyo Auto Show, Mugen Motorsports even built a bonkers road-car concept.
The Mugen RR was more than a simple farewell to the NSX. For starters, Mugen built custom engine mounts, subframes and a whole new gearbox in order to change the engine's mounting position from transverse to longitudinal. That's an awful lot of effort for some reduced drivetrain loss and better exhaust flow. The 3.2-liter V6 was also modified, now fed by a central air intake worthy of those retired Abarth engineers' respect.
That leaves us with one question: