Without a doubt, the most famous exhaust system is the so-called “spaghetti exhaust” that appeared on the 1967 Ferrari 312 Formula One car. The sinuous pipes sat prominently on the V12 engine, and one could not help but notice them because of their bright white coating.
Ever since I saw a picture of this car, it has captured my imagination. It wasn’t pure aesthetics, this elaborate and artistic design looked like a pipe organ gone mad. It turns out, that analogy is not far off. The design is pure function and was based on some of the same principles of musical harmonics.
While overall the performance of the Formula One car was unremarkable, this famous exhaust is an icon of 60s Grand Prix racing. Long before the days of CAD drawings, this masterpiece, that was perfect in both form and function, was the culmination of the last era when Formula One cars were built with heart.
The Ferrari 312/67 F1 car appeared in the second year of a new rules package in Formula One. A maximum 3.0L displacement was allowed for normally aspirated cars, and just 1.5L for forced induction cars. Rather than start from scratch, Ferrari repurposed a 3.3L sports car engine built for the 275 P2 program. This was the same era of “Ford v. Ferrari” when the Scuderia was facing a frontal assault from Detroit.
Mauro Forghieri was in charge of the Ferrari motorsports department at this time. He was a wunderkind who had started working in Maranello in 1960 when he was 25 years old. He got the “big” job only after a faction led by Carlo Chiti left to join a rival team.
Forghieri proved his worth in short order and was responsible for many of the Ferrari “greats,” including the 250 GTO and P4. He retired from Ferrari in 1987 and did some short stints at Lamborghini and Bugatti. The 87-year-old still lives in Turin.
Forghieri’s Type 242 engine was a 60-degree V12 with double-overhead cams with three valves per cylinder. The fuel delivery was a Lucas fuel injection capable of 390bhp at 10,000 rpm. Cars of this era hadn’t yet developed aerodynamics beyond a low-slung, cigar-shaped chassis.
The 1966 Ferrari F1 had the exhaust ports on the lower, outside of the engine. Thus, the exhaust pipes were also positioned low and on the sides. In 1967, Forghieri had a better idea to try to improve its power by inverting the inlet and exhaust ports. The inlets were positioned between the two camshafts, and the exhausts were at the center of the V. It debuted at Monza with yet another upgrade, as a fourth valve had been added to each head.
Forghieri wrote in his autobiography: “We had modified the heads, placed the exhausts at the center of the cylinder bank V to reduce the transverse bulk of the car, which was fundamental to improving the top speed at the time and enabled us to return to the much smaller size of the 158 F1.” By porting the exhausts in the center, the exhaust pipe was now on top of the engine for all to see.
Unfortunately, the car was never competitive because the V12 engine was too unreliable. Even worse, popular Italian driver Lorenzo Bandini suffered a fatal crash in Monaco. Scuderia Ferrari could only manage fifth in the World Constructors Championship, with a measly 20 points and zero wins or pole positions.
The job of an exhaust system is to evacuate spent combustion gases as quickly as possible, but they are much more complicated than most know. When designed properly, they dramatically increase an engine’s power, by efficiently moving air around at unimaginable speeds.
First, a quick primer. When an exhaust valve opens, a pressure wave races out at the speed of sound, and the gases follow behind it. When the pipe changes diameter, for instance when two exhaust pipes merge into one, a reverse pressure wave rebounds back down the pipe toward the piston.
An MIT paper published in the 1940s reported that if the firing frequency resonated with the natural frequency of the exhaust system, it would increase performance. What they learned was if the reverse pressure wave were timed right, it would arrive and clear out the last gases, and creating lower pressure in the cylinder which pulled in more fresh gas/air mixture on the intake. The process is happening so fast, that it is literally like tuning an instrument to get it right for a specific rpm range. This is a wildly over-simplified explanation, but it is the general idea behind exhaust scavenging.
It was not well understood until the 2.5L Grand Prix cars of the 1950s, although there are reports that German manufacturers were experimenting with it in their pre-war cars. The goal of the engine designer is to have the negative pressure arrive precisely at the overlap period when the exhaust and intake valves are open.
The length and diameter of the pipes are designed to be resonant. Most importantly, the collector (where two pipes merge and create a new cross-section diameter that generates the negative pressure) needs to be exactly the right distance from the exhaust valve.
Even today, making custom exhausts is an intensive, exacting process. However, back in the mid-60s, it was more than a process, it was an art. If exhausts were works of art, the 312/67’s is the Mona Lisa.
The 312/67’s exhaust system is divided into quarters, with each side being a mirror image. The front three cylinders on each side have three pipes of exact length that meet up in a collector, then exit out a straight tailpipe. The forward set rises up and rests on top of the pipes that serve the rear cylinders. This group extends outward, but sits lower, extending the pipes about a foot farther than the others. The exhaust tips ever-so-gently flare out which is so gradual that one does not notice.
The craftsmanship is unreal. There are no visible seams or welds. The four tri-collectors merge as if they were forged that way. The curves are gentle, lest they create undue angles that could restrict airflow. Finally, the entire set is distinctively painted with a heat-resistant white coating -- a striking choice. I could find no documentation as to why that was done, but I suspect it was to help repel heat. However, I'd like to believe that a small part was because they were so damn proud of these beauties that Ferrari wanted to put a spotlight on them!
While the design didn’t produce results on the track, this exhaust system -- more than any other -- illustrated the complexity and artistry, which not only looks great, but is essential to getting the most out of an internal combustion engine. The design may have been similar in complexity to others, but none were as “in your face.”
Until my curiosity caused me to look more deeply into these, I did not have a true appreciation for the art and science of exhaust systems and there is no higher expression of this than Forghieri’s “spaghetti” design.
