By Mark Halper
Posting in Energy
Treehuggers, get your head around this: Turbochargers, often associated with loud, environmentally obnoxious cars, improve fuel efficiency. Will the turbocharger kill the electric car star?
What word leaps to mind when you hear “eco-friendly car?” Probably “electric”, “hybrid”, “small”, “lightweight”. Maybe even “carbon fiber” (yes that’s two words wise guy) “hydrogen” or “solar-powered.”
Try this one: “turbocharger”.
While the average treehugger might associate the turbocharger with loud, souped-up, environmentally obnoxious cars, the fact is that a turbocharger – known for making cars more powerful - can improve the fuel efficiency of an internal combustion engine.
Turbochargers force compressed air into the engine’s cylinder, which creates more room for fuel and delivers more bang when the air/fuel mixture ignites.
Exactly how much more mileage the technology delivers seems to be a matter of debate, or perhaps of how you deploy it.
"A diesel engine fitted with a turbocharger can go 40 percent further and a gas engine 20 percent further on a liter of fuel,” according to a Reuters story. For instance, the article notes that a turbocharged 2012 Ford Explorer gets 23 miles per gallon, compared to 20 mpg for a non-turbocharged version.
Wait a minute. Twenty-three mpg is 15 percent better than 20 mpg. Sounds good, but it fall shorts of the 20 percent claim. Twenty percent seems to be the maximum, not the norm.
"The turbocharger is a green technology in the sense that it's helping cut emissions and raise fuel economy," Honeywell Turbo Technologies vice president Craig Balis said in the Reuters piece. "It's a critical component to get more fuel efficiency out of the engine." Honeywell is the world leader in turbochargers, according to the story. It supplies them to BMW, Volkswagen, Renault, General Motors, Mercedes and others.
What are others saying? The website Autospeed notes that in an Australian test, a turbocharged Skoda 2.0 FSI used 8.1 liters of fuel per 100 kilometers, compared to 8.5 liters without a turbocharger. That’s an improvement of 5 percent, which is well below the 20 percent mark. The test also showed a 5 percent reduction in CO2 emissions.
Whether the fuel improvement is 5 percent or 40, there does indeed seem to be something environmentally friendly about turbochargers.
Or are the turbocharger folks just blowing smoke? That’s an apt euphemism by the way, because turbochargers have another quality that should please environmentalists: they make use of a car’s flowing exhaust, which spins turbine blades that in turn operate a compressor that forces in the air that basically fans the flames of ignition.
Turbochargers aren’t even directly responsible for the window-rattling noise coming from your pistonhead neighbor’s driveway – you can thank his exhaust modifications for that.
The turbocharger movement is one more example of how the internal combustion engine is fighting back against electric cars and other glamour pusses that would unseat them in an increasingly environmentally conscious market. Recent reports from China and the UK note that consumers prefer internal combustion improvements over EVs.
One experimental car maker, Automotive X Prize winner Edison2, has reported that the new electric model of its Very Light Car actually weighs more than its internal combustion edition, although even with the extra weight, the electric version gets three times the mileage of its fossil fuel sibling.
Of course, turbochargers add cost and price to a car, but only hundreds of dollars – negligible when compared to the premium of buying electric.
On the environmental downside, there’s a hazard that consumers will get lulled into carrying on with a fossil fuel habit that would continue expanding the planet’s carbon footprint, even if internal combustion engine technologies become more efficient. An “efficient” turbocharged 23 mpg Ford Explorer is still an eco disgrace compared to ambitions of 100-mpg equivalence on newfangled electric cars.
To paraphrase an old song: will the turbocharger kill the electric car star?
Photos: Ford. Diagram: Snoopy260909/Wikimedia Commons
Sep 18, 2011
The obvious reason for the benefit of the Turbo is that you get more power from a smaller (and lighter) engine. The not so obvious but more important one is this: A Turbo engine will run without boost relatively optimized at a lower horsepower output. We as customers ask for cars that are powerful in acceleration but in truth we tend to run most of the time at a low power requirement. When you drive along the highway you may only be using 20 or 30 hp. The trouble is that especially gasoline engines at that level are not running in an efficient field and in most cases the throttle is almost closed. This closed throttle creates a vacuum. The vacuum in turn creates artificial restriction or "pumping losses". In a turbo engine you essentially have a smaller engine that runs a less restricted throttle at low power and gets its maximum power with over atmospheric boost. This allows for a more optimized engine at low power requirement while still giving the peak. This is especially important with gasoline cars and while most have only been tuned for performance we will see more and more variable vein (adjustable) Turbos for this dual mode application. In a diesel it is not as important because the Diesel does not run with a throttle but only with metering fuel... They do not have pumping losses as such like the gasoline cousin. However they need compression to get ignition so the boost is nice. There is another overlooked feature of the Diesel... There is 15% more energy in the fuel per BTU by volume so it stands to reason it gets better mileage. The BTU content and the lack of pumping losses is the reason for the Diesel being more efficient. We at Edison2 did win the XP on a gasoline car with a turbo and extreme exhaust gas recirculation. This means that instead of closing the throttle (and creating a vacuum) we just injected exhaust and let it act as inert gas. This way we were able to run with little vacuum at 5.3 hp at 60 mph while delivering 40 hp for acceleration on full turbo boost with no exhaust gas recirculation. This exhaust trick with turbo will be the future of the gas engine... The other trick is - if you can disconnect 1/2 of the crankshaft. Right now Edison2 is developing a 2+2 boxer engine with Turbo that runs on 2 or 4 cylinders depending on demand. The total engine is 660 CC and can be tuned all the way to 100 hp which in the Edison2 VLC gives you 100 mpg in the EPA drive-cycle but also Porsche performance. We are looking for corporate development partners. On the electric mileage ; Yes the VLC electric gives you +2.5 times the number in the EPA cycle but that is misleading. Electric cars have great numbers because the way the measurements are done. In certain circumstances they are better and in others they are worse. We built the electric VLC because it clearly demonstrates the superiority of our 4 seat platform over all others. In the end a car is efficient if it is easy to push the box... low mass and low aerodynamic drag are the only main virtues... We do see the electric here to stay but only if the manufacturers embrace a new box similar to what we propose. The batteries are otherwise too expensive or the charge times too long. VW with the NILS and Audi with the Urban Concept are supporting this direction as are others like BMW I drive or Opel One. It is time to change the box. It is also time to reconfigure the Internal combustion engine and that is why we will see the turbo reign supreme. Or, like in our new engine, even a three mode engine. The electric has the great advantage of just rolling along and not having such a drastic sweet spot... Although we are also finding that counter to some manufacturer's limited knowledge even there are sweet spots.... The truly great opportunity lies in the fact that most of this is in its infant stage and there is a lot of work to be done on all fronts when you embrace this rethinking and there is a lot of room for improvement.... There should be a new automotive revolution here... We can and eventually will reduce our fuel consumption from transportation by a factor of 2.5 plus as well as the pollution. It is just a question of when and that is driven by the public having to ask for it because large legacy corporations will not easily dismiss all they know and all they have. It is up to the consumers...
The habit of the American automobile has been to put more engine than necessary in a car. So, if your vehicle is already over-engined, adding a turbocharger will not do anything more than to launch your vehicle off the line quicker! But, if you put a smaller engine in your vehicle, underpower it so to say, then a turbocharger will add *TREMENDOUS* advantage to the gas mileage of the vehicle! When Oldsmobile put the first turbocharger in a production car (the 1962 Jetfire) it was added to a 215 Cubic Inch engine that barely put out 150HP...and this to push a 3,000+pound car. The turbocharger was able to get this car to launch quickly off the line yet the smaller engine was able to sip fuel on the highway...as long as you can keep your foot out of it!
"...a turbocharged Skoda 2.0 FSI used 8.5 liters of fuel per 100 kilometers, compared to 8.1 liters without a turbocharger. That???s an improvement of 5 percent,..." Wait a minute, if it used 8.5 with the turbo and 8.1 without the turbo, that means there was no improvement, since 100 kilometers divided by 8.1 is bigger than 100 kilometers divided by 8.5 liters...
There is nothing new here. The known advantages of turbocharging are hardly new; and turbochargers have been around for generations, even in vehicles that were anything but loud, souped-up, environmentally obnoxious cars. (My sister's SAAB, hardly a hot-rod, had one) The main downside to widespread adoption of turbocharging was the added cost and complexity to the engine, as well as the additional maintenance and repairs required over the long haul. It's all about scalability. Turbocharging merely make an engine of a certain size more powerful. The concept works the same for smaller engines as it does for larger ones. Since smaller, lighter engines mean better fuel economy, they made sense on those grounds. It remains to be seen of the overall cost of ownership makes them worthwhile, however.
I was just looking at that myself! Using the example that the OP gave, it would appear that the turbocharger used *MORE* fuel than the non-turbo'd engine! I can only suspect that he has his facts backwards...
Ah! Great catch FuzzyIce. I wrote that backwards in the version you read, and I've now corrected it. The turbochargeed version used 8.1 liters per 100 km. The non-turbo version needed 8.5 liters, or about 5% more. Many thanks for pointing out the error and keeping me on my toes.