Hello! Welcome back to this third and final installment in our “History of the Turbocharger” Series. If you haven’t already, you can read the previous installments by clicking the links below:
Now, let’s see how the turbocharger went from an ace-in-the-hole for aircraft engines during World War II, to the go-to way to crank out horsepower in small engines.
Up until World War II, turbochargers were not a common sight in cars, and certainly not the most popular option for adding forced induction to an engine. Even following the war, some of the most notable post-war aircraft relied on piston engines as opposed to the modern turbojet engine, did not use turbochargers. Most R&D efforts for military aircraft propulsion was moving away from piston engines, and where piston engines were being used, they didn’t have turbos.
Take, for example, the Corvair B36. This behemoth of an airplane was adopted by the US Air Force for a short period of time after the war, but before the much more famous B52 Stratofortress was adopted. This gargantuan plane made use of a Pratt and Whitney radial engine similar to (although much larger than) the engines used in other US warplanes during World War II. Much like the other engines used by warplanes, these engines were typically not turbocharged, instead used geared superchargers to force more air into the 6(!) propeller engines.
From the get-go, this engine was quite dated, as the piston engines were maintenance heavy, and the unusual engine and propeller configuration gave the plane reliability issues. Additionally, the Peacemaker was retrofitted with 4 jet engines for use in takeoff as well as speed over a target to reduce the likelihood of being struck by enemy fire. It wasn’t long however, before the turbojet-powered B52 we all know and love was adopted. The B36 was more or less forgotten as a massive placeholder for the US Air Force for a short time following World War II.
So, if turbochargers really didn’t have a future in the skies with military aircraft or commercial airliners, where did they belong? You probably already know the answer if you’ve seen a small sedan drive by, or heard a semi-truck trundle on past you.
Turbochargers slowly found their way into cars, but how did they get there?
As we learned in the previous article, turbochargers were implemented into trucks before the Second World War in limited capacities and had become a good option for adding power in diesel-powered ships. Cars had been an exception, but that changed when turbochargers started finding use in racing in the 1950’s.
American hotrodders were an early adopter of turbochargers in cars, specifically, drag racing, and straight-line speed events. Turbochargers were relatively unproven technology, but offer an awful lot of potential horsepower. Racing was a great proving ground for the turbo. As Bill Cuttitta writes at Grassroots Motorsports, “After the war, experience with turbocharger technology led engineers to experiment with automobile applications during the 1950s and ’60s. Home-built hotrods and race cars sporting turbos began appearing at dry-lake speed events and even NHRA drag races. Before long, manufacturers were considering them for various race and production car applications—and soon enough, they did.”(1) In 1952, Cummins made a big splash when they entered a custom built engine and truck in the Indy 500.
Cummins built a custom 6.6 liter diesel engine fitted with a turbocharger, with the engine block made from magnesium with aluminum cylinder heads. The engine was installed at an 85◦ rotation, and was practically laying on its side, which gave the racecar a low center of gravity. The turbocharger generated 20 PSI of boost for the engine at full chat; and the engine cranked an impressive 380 horsepower at 4,000 RPM, going all the way up to 430HP at 4,500 RPM. Those are impressive power figures today, let alone almost 70 years ago!(1) This car marked a lot of firsts at Indy, including it being the first use of a turbocharger at Indy, the first use of independent front suspension, and it marked the first Indy racecar that had its chassis aerodynamically optimized in a wind tunnel during development.(1) Although the racecar did not do well, thanks to a turbocharger failure from debris ingestion, Cummins had proven a point; and Indy soon banned diesel-powered cars from competing.(1)
It would be another 10 years before the turbocharger made an appearance in road-legal cars. In 1962, General Motors released the Chevrolet Corvair Monza and the Oldsmobile Jetfire.(2) It should be noted that GM and Chrysler both dabbled in gas turbine powered cars in the 1950’s, before GM released the Corvair Monza and the Jetfire. Unfortunately, as is often the case with brand new technology in cars, the turbocharged engines had reliability issues, so their time in the market was limited, as was their popularity.(2)
So even after GM’s initial entries into the turbocharged car sector, there wasn’t a lot of consumer demand, and to be fair, it’s easy to see why. Turbochargers were an expensive and unproven technology thus far. The added pressures on an engine from a turbocharger could make the engine unreliable, and worse, significantly shorten the life of the engine if it wasn’t properly engineered to account for the added pressures. Additionally, turbocharged engines suffered from horrendous turbo-lag, because variable geometry technology and other workarounds hadn’t really been explored. For those who may not know, turbo-lag is the delay in throttle response and engine performance when a turbocharger has not “spooled up” yet, and is not yet getting enough exhaust gas from the engine in order to drive the turbine and provide boost. While engineering R&D has provided numerous workarounds in modern automotive engineering, such as anti-lag systems, twin scrolls, and changing the geometry of the turbocharger, these technologies had yet to be explored in the mid-20th century.
What finally kicked things off for the turbocharger?
The final catalyst came in 1973, when OAPEC proclaimed an oil embargo, gas prices soared, and in the United States (the largest manufacturer of cars before the crisis), the massive displacement, naturally-aspirated engines seen in most production cars were suddenly very unpopular. Thanks to their heavy fuel consumption and the spike in oil prices, most drivers did not want gas-guzzling, big-block V8 engines in their family sedans. As the 1970’s progressed, increased federal regulation led to the Big Three (Ford, GM and Chrysler) to downsize a lot of their offerings, and look for ways to make their engines energy efficient and also emit less carbon dioxide into the atmosphere.
Unfortunately for the Big Three, there were a lot of missteps in the forms of quality control issues, and these combined with middling success in making cars that appealed to people, led to the US being overtaken by foreign auto entities like Toyota, Honda, Nissan and Volkswagen.
As more and more economy cars were imported with smaller engines, the competition to make the most powerful yet economical car heated up, and the turbocharger was called on once again to increase engine efficiency and power without making larger displacement engines.
Perhaps one of the best (and perhaps earliest) example of turbocharger becoming the gold standard in automotive applications is in turbodiesel engines for both light and heavy trucking, as well as in passenger cars. Thanks to the way diesel engines operate regularly, mating a turbocharger to a diesel engine can result in major improvements to power output and efficiency. Although some passenger car turbodiesels were abysmal failures, there were also massively popular engines, like Navistar International’s T444E, which debuted in 1994 as the Ford Power Stroke engine in Ford’s heavy pickup trucks. The Cummins turbodiesel B series engines were also massively popular in the commercial and passenger market, in everything from school busses to pickup trucks.
In diesel trucks and in passenger cars alike, we are still seeing an increase in the use of turbochargers to help engines use less fuel, emit less, and still generate unheard of amounts of power. A big part of why turbochargers are almost universally used in diesel engines, and are increasingly common in gasoline powered cars, is because of the improvements in engineering that has occurred in leaps and bounds since the late 20th century.
With the advent of computer simulation programs such as AxSTREAM by SoftInWay and GT-POWER by Gamma Technologies, turbocharger design and simulation has become far easier and less time consuming than it had been. Projects that would take years for engineers to complete could now be done in 1 year, as the arduous task of turbo-system integration into a conventional combustion engine could now be done in less time. Remember though, that it is not just enough to design a conventional turbocharger in the age of miles per gallon and 0 to 60 times; the turbocharger must be able to perform. This is where tools for centrifugal compressor and radial turbine design come in; being able to create different designs that take advantage of variable geometry technology or twin-scrolls are critical in making a turbocharger that competes in the current automotive market. Engines like Ford’s Ecoboost lineup are making use of the latest in turbocharger system technology to power everything from Ford’s economy cars like the Focus and the Fiesta, to performance vehicles like the Raptor, Mustang, and even the second generation of the Ford GT.
So what does the future hold for turbochargers?
Well they’re certainly not going anywhere! OEMs have been increasingly turning to turbochargers as seen with Ford, and General Motors and Fiat Chrysler have been following suit, with GM producing the Ecotec line of turbocharged engines. Performance cars and racecars like the Bugatti Chiron, and all Formula 1 cars utilize turbochargers for the utmost of performance in the automotive world; with the big exception to turbocharging being big-displacement V8 engines commonly seen in American muscle cars, and some European sports cars. Even then however, turbocharging is creeping in as the “go-to” for added horsepower and emission compliance. So long as piston driven engines are on the road and using fossil fuels, it seems the turbocharger is here to stay.
Thanks for following along on our 3 part series covering a brief history of the turbocharger, from inception to the modern day. If you haven’t already, be sure to register for our special webinar on turbocharger engine integration using AxSTREAM and GT-SUITE, happening on September 2nd at 10AM Eastern time.
- Peace, William.“Cummins Diesel Indy 500 Racers”. Old Machine Press. 21 August 2020. Web. https://oldmachinepress.com/2019/01/20/cummins-diesel-indy-500-racers/
- “History”. BorgWarner. 21 August 2020. Web. http://www.turbos.borgwarner.com/products/turbochargerHistory.aspx