Are Naturally Aspirated Engines Going Away?

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Are Naturally Aspirated Engines Going Away?

In the race to improve efficiency and cut emissions, more and more automakers are turning to forced induction as a way of increasing fuel economy without sacrificing drivability.

The Next Big Automotive Extinction

And it’s quite possible they could go the way of crank starters, leaded gasoline and big-block V8s. “From our engine lineup today we’re pretty committed to this downsized, turbocharged approach,” said Doug Skorupski, powertrain strategy manager at Volkswagen of America.

Volkswagen EA888 EngineIn fact VW only has two naturally aspirated engines in its North American lineup today. “The 3.6 [V6] and the only other one, and it goes away this summer, is the 2.0-liter MPI,” said Skorupski. In his opinion, “[It’s] only a matter of time before the naturally aspirated engine out serves its useful purpose.”

For years automakers have been adding things like variable valve timing and direct fuel injection to increase the efficiency of these atmospherically charged powerplants. But they’re starting to run out of options. “I don’t think there’s any low-hanging fruit [left],” noted Skorupski. Sure, there are still some options on the table but he said they can be very costly.

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Ben Schlimme, executive program manager at the Toyota Technical Center echoed much of what Skorupski mentioned. When asked if naturally aspirated engines would ever disappear he said, “The easy answer is ‘no’ because forever is a long time.” Still, in developed markets like the U.S. he noted, “I see IC [internal combustion] engines needing to be around for at least 15 years or more.” After that, who knows?

Staying Power

Despite falling out of vogue in recent times, un-boosted powerplants are not without their merits. “Obviously simplicity and cost,” said Schlimme, are two upsides that are easy to recognize, but that’s not all. “The other advantage of an NA engine is packaging.” Not having to cram as much stuff under the hood can be “a huge advantage to deliver fuel economy,” he said.

2015 GM V8LT4 Cutaway

Naturally aspirated engines can also be better down the road as miles and year accumulate. “Certainly the repair costs of a turbo is going to outweigh that of an NA engine,” said Schlimme.

When it comes to forced-induction Skorupski had similar comments. “There is a cost associated with these motors.” There are more components to deal with and lots of extra plumbing, none of which is free. Simply put, “Turbos are more expensive,” he said.

Hybrid Salvation

“A lot of the naturally aspirated engines are mated up with CVTs … and they’re pretty efficient,” said Skorupski, but another way these powerplants could receive a stay of execution is by pairing them with batteries and electric motors.

Prius Badge“I think naturally aspirated engines may survive in hybrid applications,” noted Skorupski. By going this route you can provide good performance and efficiency along with lower cost because you “put less money into the engine itself.”

Toyota is the undisputed king of hybrid vehicles. Its Prius is practically a brand unto itself. Schlimme said, “Hybrids pair well with [naturally aspirated] IC engines,” noting that this strategy is a “good path forward.”

Real-World Benefits

Curiously the Big T has been a little late to the downsized, turbocharged party. In fact they just introduced a new 2.0-liter four-cylinder unit in the Lexus NX 200t crossover years after competitors have done the same. Despite the delay this company does have a history of forced induction. “We had turbos back in the day,” but ultimately they were discontinued, “because we couldn’t’ make them emissions compliant,” Schlimme said.

2015 Toyota Camry V6 Engine

Fortunately thanks to modern features and computer controls, force-fed engines can provide many benefits to customers. “They enjoy the drivability feel of the latest technology that’s been brought to market,” said Schlimme. These engines typically have lots of torque for speedy getaways, and depending on how they’re driven, downsized, force-fed powerplants can be fuel efficient.

Despite missing this latest powertrain fad Toyota has been very successful in delivering good performance and perhaps even better fuel economy with its naturally aspirated engines. This is an area where some of its competitors who are fielding more technically advanced powerplants have fallen short. Ford’s EcoBoost lineup is a prime example of this.

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“I think that our Toyota position is that we under promise and over deliver,” noted Schlimme. “At times larger engines at lighter loads can be more efficient,” which is something they’re keenly aware of. Accordingly they’ve leveraged their naturally aspirated technology and optimized automatic-transmission tuning to deliver impressive real-world economy.

But don’t think they’ve completely missed the boat. Assuaging any fears Schlimme said, “Toyota isn’t going to be left out of the turbocharged engines.” Perhaps their new 2.0-liter unit is just the tip of the iceberg. Are Naturally Aspirated Engines Going Away?

2015 Golf Sportwagen Numbers

Volkswagen’s had success with its powertrain strategy and a prime example of the efficiency gains that downsizing and boosting can provide is their Jetta SportWagen. When equipped with a manual transmission the 2014 model stickered at 23 miles per gallon city, 33 highway and 26 combined. Its 2.5-liter five-cylinder engine delivered 170 hp and 177 lb-ft of twist.

In comparison, the 2015 Golf SportWagen features a 1.8-liter turbocharged four-banger under its hood. This engine provides 170 horses and 184 lb-ft of torque. But the biggest gains are on the efficiency front. According to the EPA this car should return 25 MPG city, 36 highway and 29 combined.

Teaching an Old Dog New Tricks

Forced induction, hybridization and even alternative fuels are clearly the way forward, but that doesn’t mean there aren’t some promising technologies on the horizon that could significantly improve the performance of naturally aspirated engines.

GM HCCI“I think … what you’re seeing is likely a bit of convergence with compression ignition and more advanced combustion technologies,” said Schlimme. This includes something known as HCCI, or homogeneous charge compression ignition, which sort of blends the characteristics of a diesel and gasoline engine. In this combustion process the air-fuel mixture ignites spontaneously under pressure without the need for a spark plug. Lower emissions and better efficiency can result.

“Lean burn is very similar in that regard,” added Schlimme, a situation where much less gasoline is introduced into a combustion chamber than normal, “Which allows it to decrease fuel consumption.” Though just like HCCI this technology is not ready for primetime.

While under siege and losing ground to forced induction it appears as though the naturally aspirated engine is here to stay in the near term and probably longer in certain applications or even global markets where packaging, cost or simplicity are key.

Discuss this on our Alternative-Fuels Forum.

  • Jonny_Vancouver

    I’m a fan of the NA engine vs forced induction for the reasons stated above: cost, simplicity, hybridization. It just makes sense.

    I see forced induction engines needing years more (a decade?) development before they become as reliable and cost effective as NA engines, and running parallel to forced induction tech you have hybrid powertrains which is the direction we should be moving in imo.

    Can you imagine where we would be today if we had been developing the electric car since 1837 when the first one was made? So much global economic and environmental stress would have simply not existed to say the least, but the oil industry has for the most part been about greed and profit.

    So where does that leave us today? I see forced induction as a technology that doesn’t need to be developed. It equates to our reliance on fossil fuels being stretched out for as long as possible, and that only profits a select few. Whereas hybrid and electric tech profits us all. Keeping in mind this technology has other applications as well and automakers are probably in the best position to further this technology.

    Sorry for the rant, but its always about the big picture. With money being tight all around for most folks (insert cost of purchase, maintenance, repair of forced induction vehicles) the environment in crisis, oil companies bleeding us dry, and an available, viable alternative technology… How can we even consider traveling further down the path of forced induction and adopting that mindset? When we should, in light of the big picture, be moving away from it.

  • Brad Barefoot

    I hope the N/A engines hang around, in the still developing countries EFI and other things we see here in the States daily would be a big repair issue in say the Kenyan outback.

  • smartacus

    the future is electrically assisted turbos and battery electric superchargers

  • njlou

    I am a fan of the NA engines for ALL the reasons mentioned. BUT for a company car, a rental or a lease, a turbo is better. LOL
    When I am paying the bills a turbo, direct injection and other techno items are not in my budget!!
    The assumption is that you will save fuel etc. – maybe – but just one dual turbo repair and your savings will evaporate – as your resale value.