Whether you prefer natural aspiration or forced induction, it’s impossible to deny that the advent of the turbocharger has had an indelible impact on the cars we drive today. You can find turbos in almost every type of car you can think of, diesel or petrol, from a VW Golf to a Ferrari 488 GTB. Not long ago, however, turbocharging was almost unheard of in passenger cars. Here’s the story of how that all changed.
Turbocharging has been around for nearly as long as the internal combustion engine itself, but it would take decades for anyone to actually stick a turbo on a passenger car engine. Although they were widely used in aircraft engines for decades, the sheer size of early turbochargers made them fairly impractical for use in automobiles. However, the obvious benefits of turbocharging meant that it would only be a matter of time before turbos would find a home under the bonnet of a car.
If you were to think about the first cars to have turbocharged engines, you might think about classic cars made in Europe. In fact, a lot of early turbocharged cars were European - cars such as the Porsche 930, Saab 99 Turbo and the BMW 2002 Turbo.
However, the first car to ever get boost was as American as apple pie. Back in 1962, General Motors decided that the 3.5-litre V8 under the hood of the Oldsmobile Cutlass just didn’t have enough power. Instead of looking to GM’s legendary arsenal of small and big-block V8s, however, Oldsmobile decided to do what nobody else had done before. Working with industrial turbo manufacturer Garrett, Oldsmobile created the now-legendary JetFire V8 in 1962. It was available as an option package on the F-85 Cutlass that same year.
Putting a turbocharger in a mass-market automobile presented huge challenges for engineers in the 1960s. The JetFire engine had a compression ratio of 10.25:1, which made it vulnerable to engine knock without modern-day engine management. Oldsmobile got around this problem by using a system to inject ‘Turbo-Rocket Fluid’ into the cylinders. If you’re an avid turbo tuner, this might sound a bit like a water-meth injection kit. In fact, it was -Turbo-Rocket Fluid was actually just a 1:1 mixture of water and methanol.
Although the JetFire made the Cutlass noticeably quicker than its naturally-aspirated twin, it never caught on with the public. Part of the reason was the JetFire’s price - the $300 premium for forced induction was astronomical in 1962, seriously hampering its commercial viability. The JetFire wasn’t too reliable, either; and the Turbo-Rocket Fluid injection system proved to be impractical. Less than 4,000 JetFires were ever sold, and Oldsmobile pulled the plug on it after just one year of existence.
Although the JetFire failed in the market, it didn’t take long for the auto industry to figure out the untapped potential of turbocharging. In 1965, the second mass-market turbocharged automobile was put on sale. Although you’d think it would be one of the European sports cars I mentioned earlier, this vehicle was actually an American 4x4. The International Harvester Scout was available with a turbocharged 2.5-litre four-cylinder from 1965 to 1967. It produced around 110bhp, 20 more than the naturally-aspirated version of the same engine. More importantly, however, it was able to do all of this with regular-grade petrol and without the use of a water-meth kit.
After only two years, however, IH decided that there was no replacement for displacement, and ditched the turbo ‘Comanche’ engine in favour of a non-turbocharged 3.2-litre four-banger. As it turned out, the bigger N/A motor was able to produce the same amount of power while using less fuel than its turbocharged cousin. With the impending 1974 oil crisis on the horizon, it seemed that the economics of turbocharging just didn’t make sense. It would be another 10 years before a turbocharger would be available on an American engine.
By 1973, automakers started to see the potential for turbos to make cars go really, really quick. That year, the legendary BMW 2002 Turbo was put into production. Although very fast, the 2002 Turbo was not without fault. It suffered from brutal turbo lag and poor fuel consumption, and was even thought to be a safety hazard. Like the JetFire, the 2002 Turbo lasted just one year before it was killed off.
As the 2002 Turbo’s days ended, the Porsche 911 Turbo came to life. When its first iteration was released in 1974, it was the fastest production car in the world. This was arguably the most significant commercial milestone for turbocharged engines. Having been associated with the most exotic dream car of the day, the enthusiasm for turbocharging began to take shape. By 1978, one year after the birth of the Saab 99 Turbo, it was clear that the turbocharger wasn’t going away.
1978 was a big year for the turbocharger. It was the year that Buick began equipping the Regal with a turbocharged V6, which would ultimately lead to the high-output Grand National. More importantly, however, 1978 would be the year in which the turbodiesel was born. That year, Mercedes-Benz released the 300SD for sale in the United States. Fitted with a Garrett turbocharger, the 300SD changed the diesel engine forever.
Although the N/A-versus-turbocharged debate continues for the petrol engine, the effects of the turbo on the diesel engine are much more profound. Because the diesel combustion cycle depends on high compression, forced induction is a simple way to improve the power and efficiency of a diesel engine. It quickly became evident that turbodiesels were far better suited to automotive applications than their naturally-aspirated counterpart. Perhaps it’s no surprise that since the introduction of the Peugeot 604 turbodiesel in 1979, turbodiesels account for around half of the motors on the road in Europe.
In 1981, Maserati decided that if you could put one turbocharger on a car’s engine, you could probably give it two. The result was the aptly-named Biturbo. While it wasn’t a particularly good car, it was the first twin-turbocharged passenger car ever sold. The theory was that using two turbos working in parallel with each other would reduce the amount of turbo lag. In practice, that didn’t always happen, but the parallel twin-turbo undoubtedly allowed engines to produce freakish amounts of horsepower.
As Porsche proved in 1986 with the 959 though, there is another way to set up two turbochargers to reduce the lag effect. The 959’s twin turbos are set up in sequence with each other. Unlike a parallel twin-turbo setup, where the two turbochargers work independently and at the same engine speed, a sequential setup involves one turbo spooling up at low RPMs and the other (or both) spooling up at high RPMs. Although this setup can be less reliable, the 4th-generation Supra’s sequential twin-turbos are reported to have an astonishingly low failure rate of less than 1 per cent.
Over the past 55 years, turbochargers have undergone a considerable transformation. Today, turbochargers are almost as technically complex as the engines they are fitted to. Twin-scroll turbos, variable geometry turbos and even belt-assisted twinchargers are just some of the advancements in turbo technology that we’ve seen so far. With turbocharged cars now extremely common thanks to the downsizing trend, you have to wonder: where do we go from here?
The next revolution might be on the near horizon. Electrically-assisted turbochargers are showing a lot of promise for future vehicles. While standard turbochargers convert exhaust gases into the electricity needed to power the compressor, e-turbochargers divert some of that electrical energy into a capacitor. That capacitor stores the energy much like a Formula One KERS system, and is used to power the compressor while the turbo isn’t spooling at optimal revs. This would, in theory, eliminate the effects of turbo lag.
It might be some time before we see e-turbos in the mainstream. However, as history has showed, the automotive industry doesn’t tend to waste a lot of time in making the humble turbocharger better than ever.