Since Ferrari first unveiled the 126 CK to the media during practice at the 1980 Italian Grand Prix in Imola, with Gilles Villeneuve as the test driver, rumors from Maranello indicated Ferrari would abandon the naturally aspirated 3-liter engine for Formula One racing. The replacement was a 1.5-liter engine with turbocharging, using an exhaust-driven turbine turbocharger. After the new powertrain was introduced in 1980, Ferrari’s turbocharged team secured their first victory at the Monaco Grand Prix in May 1981—a success for a completely redesigned engine that had yet to be fully performance-tested.
In reality, Ferrari’s V8 engines had not performed very well in F1 history. While Maranello mechanics were experienced with tuning V12 engines, those 12-cylinder units were complex and cumbersome. The 1.5-liter V6 engine in the 126 CK was a new, compact, lightweight, and powerful design. Its advantage over the V12 was the turbocharging system. Ferrari engineers installed two KKK turbochargers—effectively two turbos—on top of the engine, near the rear wall of the fuel tank. This was very risky and led to heat buildup in the heat-shielded area. The routing of various lines—fuel, vacuum, coolant, and others—was a nightmare for engineering design. Testing at Imola in September 1980 impressed executives: the V6 revved more aggressively than the older V12 T5 flat-12. The engine sounded like an old Renault turbo, somewhat dull and smooth, but with a loud shriek and some hesitation under acceleration. Only when exhaust gases spun the turbine to full speed and the compressor pushed intake air at 20–35 psi did the engine roar like a furious beast—an explanation needing no further interpretation.
At the debut of Ferrari’s V6 twin-turbo F1 engine, the Scuderia showed the new engine was not yet ready for competition and had no intention to race it in America. It was expected to be ready for the 1981 season. Italian sources reported Ferrari’s turbo engine was very fast, and the serious problem of throttle lag—engine slowdown when exhaust pressure dropped—was eliminated. One result was Ferrari abandoning the exhaust-driven turbocharger in favor of the Comprex Pressure-wave supercharger, powered mechanically by Brown Boveri in Switzerland. Because the Comprex was belt-driven directly from the engine, it did not slow down when the driver lifted off the throttle, nor did the engine RPM drop. When Ferrari arrived at Long Beach for their first FIA World Championship Grand Prix, the Comprex supercharger seemed promising, despite the presence of KKK turbochargers.
However, the Comprex system caused major problems and was abandoned before practice ended. Ferrari switched to the exhaust-driven turbochargers made by Kuhnle, Kausch & Kopf (KKK). This allowed the Ferrari 126C turbo to launch more quickly and accurately than the Renault turbo. When Villeneuve took the lead at the first hairpin at Long Beach, the 126C’s engine sounded sharp and intense. In corners, the new engine was as fast as or faster than Cosworth’s V8. During practice, the rear of the car emitted two bright orange flames when the driver lifted off the throttle; these flames were not just at the exhaust tip but deep inside the extremely hot turbine. When the driver accelerated out of corners, the orange flames disappeared. The Ferrari 126C’s launch from the grid clearly showed no throttle lag, even though this was before electric turbo controls existed.
Fundamentally, the problem with exhaust-driven turbochargers is that when the driver lifts off the throttle, exhaust pressure drops, slowing the turbine and thus the compressor. This reduces intake manifold pressure until exhaust pressure rises enough to spin the turbine back up. There are methods to keep the turbine spinning near maximum speed. Positive turbine drive can fix boost pressure issues but absorbs energy, counteracting the turbo’s purpose. Ferrari’s approach was to make the turbine act as a gas turbine under low exhaust pressure by burning fuel within the turbine.
When the throttle is closed, compressed air remains in the intake manifold even as compressor speed falls. This residual pressure is routed via a valve into the turbine inlet, reaching the high-temperature turbine blades. Unburnt fuel from the cylinders flows through the exhaust system because Ferrari’s continuous fuel injection keeps delivering fuel. By adjusting mixture concentration and turbine temperature precisely—which is extremely difficult—combustion occurs inside the turbine, causing expansion that spins the turbine and exhaust gases exit through the tailpipe. Thus, as exhaust pressure falls and turbine speed would drop, combustion inside the turbine maintains rotation. The turbine acts as a gas turbine, returning the compressor to normal speed. The intake manifold fills with high-pressure air mixed with the correct fuel amount, ready to explode with power when the driver fully opens the throttle again.
Though this sounds simple, it was far from easy. The system was complex and required stable high-speed operation over race distances exceeding 300 kilometers. Marelli’s electronics, which measured fuel flow to the injectors, had to be extremely precise. If the turbine mixture was off, nothing happened or combustion occurred at wrong times. Also, the mixture needed to remain in the cylinder correctly to prepare for full engine power. The connection between the driver’s throttle, intake manifold direction valves, compressor butterfly valves, cylinder bank throttle plates, and fuel/air measurement controls was highly complex. Both turbochargers sat atop the engine, close together on a heat shield between turbine and compressor for compactness.
Three exhaust pipes from the right cylinder bank fed the left turbine, and three from the left bank fed the right turbine—this crossover had a functional reason. Each compressor supplied air to its own intercooler, located in side pods near the front of the engine. From each intercooler, a large tapered intake manifold ran rearward to feed air to its three-cylinder bank. Near the compressor outlet, a balance pipe crossed the engine, with a valve admitting air to the exhaust pipes connected to the turbine manifold. Just imagining this was enough to induce a headache.
The intake manifolds were aluminum, and the exhaust pipes made of heat-resistant Inconel steel. Connecting these caused designers some headaches. Air flowing into the compressors came from above the chassis into L-shaped pipes for each unit. At each L-shaped intake manifold entrance, conventional butterfly valves were mounted on a shared shaft controlled by cables running forward to the cockpit pedals. This cable controlled a cross shaft at the front of the engine, moving the butterfly valves forward and backward in the intake manifold near each cylinder head. The left slide also controlled fuel injectors mounted behind the engine. The cross shaft connected two compressor inlet butterfly valves. The connecting rods ran down to valves in the balance pipe, which opened when other valves closed. What remained unclear was the operational relationship between the butterfly valves, exhaust pressure relief valves, throttle slides, and air/fuel measurement controls.
This system’s operation was evident from the Ferrari 126CK accelerating out of corners. The Monaco victory became clearer. One might wonder why Renault did not use the same system, but their basic V6 engine layout made it mechanically impossible. They completely separated the two turbos, each on opposite sides of the engine. Each turbo had its own wastegate valve to operate independently, except for butterfly valves linked to the compressors. Anyone hearing the pressure relief valves on this engine would surely be fascinated.
In the 1980s Ferrari race cars, the exhaust pressure relief system (wastegate) was a single central unit feeding pressure from both turbines, adjusted by one screw. Renault could use this system on different engine types but faced more complications than success, as it could create 30 psi pressure in one cylinder bank and only 28 psi in the other, depending on how much each turbine was "lit up," causing suboptimal engine performance. Additionally, Renault did not use slide-type throttle plates near the cylinder heads, which may have been crucial to Ferrari’s success.