The Brabham BT46: F1’s Weirdest Car?

The Brabham BT46

The Brabham BT46 Formula One race car was designed by Gordon Murray for the 1978 FORMULA 1 season. The car featured some revolutionary design elements. One such design change was the introduction of the flat panel heat exchangers for the car body to replace the old oil and water radiators.

After having been shown a picture of the mockup, engineer and consultant David Cox concluded that The BT46 had only 30% of the surface area needed to properly cool the vehicle. So, he immediately contacted Brabham to voice his concerns. Unfortunately, the car had already been put through several trials and encountered some serious overheating problems. So Brabham invited Cox over to talk about his concerns face to face. Cox pointed out to him what he viewed as some fundamental flaws in the design, and that he didn’t think the design could ever be made to work. Consequently, the design was scrapped before ever running in a race, never to be seen again.

However, the BT46, powered by a flat-12 Alfa Romeo engine, went on to compete for the rest of the season using a nose-mounted radiator, driven once by Niki Lauda and John Watson.

In 1978 The “B” or “Fan” version of the car made its debut at the 1978 Swedish Grand Prix to challenge the dominant Lotus 79. In this version, The BT46 used a fan to generate an enormous amount of downforce. It was touted as a cooling system, but, in reality, it was used to pull air from beneath the car, reducing drag.

It was the only car in the Formula One World Championship with this configuration – which Niki Lauda used to win the 1978 Swedish Grand Prix at Anderstorp.

Months after the “Fan Car” had been retired, Autosport magazine ran an article by veteran journalist John Bolster titled “Have Brain Will Travel” detailing how they pulled it off and crediting Cox with coming up with the idea and the numerous calculations involved, and identifying the many legal loopholes and how to circumvent them.

In a later Autosport article, dated January 3, 1980, another Cox project was featured where the highly-respected racing historian Doug Nye unambiguously credited Cox with the “Fan Car” idea.

Brabham pulled the plug on the fan car concept after only one race, even though the FIA had ruled that it could compete for the remainder of the racing season. Gordon Murray, the car’s designer, said later that Brabham’s decision to pull the car was due to concerns expressed by Bernie Ecclestone, the team’s owner. Ecclestone had become chief executive of the Formula One Constructors Association (FOCA) the same year the Brabham BT46 made its debut and was concerned that blowback from other racing teams could cause the FOCA to collapse. In a 2008 interview, Murray said that, at that time, Ecclestone’s primary concern was getting his foot in the door at the Formula One Constructors Association and realising his dream of becoming the group’s chief executive, which he went on to become.

The Brabham BT46 Concept

The first Brabham to carry the Alfa Romeo engine, the Brabham BT45 was bulky and overweight, weighing in at 625kg and pushing the F1 width regulations to the limit. This was due in part to difficulties encountered trying to fit the huge Alfa Romeo Flat-12 engine, and the requisite fuel tanks, into the car’s body. After a long development process, the car did manage to compete respectfully but never won a race. It was after this experience that Gordon Murray embarked upon his ambitious quest to design the BT46. The new design would compensate for the extra weight and fuel tanks while making technological advancements that would improve safety.

The Brabham BT46 Engine and Transmission

Alfa Romeo’s performance-enhanced flat-12 engine weighed in at 2995cc and came with fuel injection and electronic ignition. The engine sported a cast magnesium alloy block with an aluminium crankcase. It also featured aluminium or magnesium cylinder heads.

Each cylinder had four gear-driven valves. By 1978, one Formula One iteration delivered around 520 bhp at 12000 RPMs. This was around 50 bhp more than the popular Cosworth DFV engines used by most other racing teams at the time. Combine that with 324ft. lbs of torque and the resulting output was enormous.

However, all of that extra power came at the expense of space, less fuel and oil efficiency, and added around 40 kg extra weight. Plus, The engine was difficult to maintain, as there were significant size variations between one unit and another.

The gearbox used in this car was a revised, lighter version of the 6-speed gearbox used in the BT45B. It was designed by Brabham, but cast by Alfa Romeo and outfitted with Hewland gears.

The Brabham BT46 Chassis and Suspension

Like so many other Gordon Murray designs, the Brabham BT46 featured an aluminium alloy mono scope trapezoid cross-section that the designer was known for. It also featured built-in pneumatic jacks connected to an external compressed air supply that raised it off the ground for tire changes during practice sessions. The design called for a very early version of the carbon brakes that had been adopted universally by the time the 80s rolled around – a concept borrowed from the airline industry.

Brabham’s system, which he had been trying to perfect since 1976, combined the carbon composite brake pads with steel disks with the faces being puckered with carbon fiber pockets.

What was probably the most radical design feature of the BT46 was its use of the flat plate heat exchangers mounted flush against the surface of the car’s body, in place of conventional radiators. The innovation allowed Murray to compensate for some of the space taken up by the unusually large engine and requisite fuel tanks. The result was a lighter design with a lower frontal cross-section (a must for aerodynamic purposes).

However, under real racing conditions, the heat exchangers failed to deliver anywhere near the cooling capacity needed, one of the South African-born Murray’s few design failures. The heat exchangers were soon scrapped in favor of more traditional radiators like the ones used in its predecessor, the BT45B, taking away some of the aerodynamic efficiency it had gained with the previous design.

The Brabham BT46 Racing History

The Brabham BT46 made its debut in the third race of 1978 in the South African Grand Prix on March 4, 1978, sporting the revised version of the nose-mounted radiators. The car became competitive almost immediately, though there were some questions about its reliability.

After a successful debut and the subsequent scrapping of the fan car idea at the Swedish Grand Prix, the Brabham team returned to the standard BT46 model to finish the season. It was this version that powered Niki Lauda to victory at the 1978 Italian Grand Prix, albeit after Andretti and Villanueva had been penalized a full minute for jumping the gun for the second start. The race had been paused after Ronnie Peterson’s fatal crash after the first start.

The BT46 made its final appearance in the Formula One World Championship in the first round of the 1979 season. It was driven by Nelson Piquet. Niki Lauda also chose the BT46 for qualifying, as the BT48 model had proven to be too problematic. Unfortunately, the race ended quickly for Piquet and his BT46, as a multi-car pileup put an end to its storied career.

The Brabham BT46 Fan Car: How it Worked


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