The CAFE crystal ball — The future of the powertrain

By Christopher A. Sawyer
The V
irtual Driver

(December 31, 2013) Dr. David J. Brooks, Product Group Director, Engines at Ricardo Engineering,
may be British, but he isn’t some U.K. propeller head for whom future powertrains are an intellectual exercise. “When I moved to the States,” he says with a smile, “the first thing I bought was a Hemi-engined [Dodge] Challenger. If I was going to be living here, I had to check that box.”

So what does the automotive future look like in light of coming fuel economy an emission standards?

According to Brooks, there will be few dramatic changes in powertrains in the next few years as OEMs meet the new CAFE standards with existing technology. Downsizing has begun, the number of boosted engines are increasing almost as quickly as the number of gears in transmissions, and variability is being added to both intake and exhaust cams. Electric boosting — a super capacitor-driven electric turbocharger that fills the torque troughs the larger exhaust-driven turbo can’t meet — will follow.

Working in tandem with a belt-driven starter/generator, it adds power directly to the crankshaft when not providing boost. Hybrids, driven by CAFE subsidies, will be more common, but still bit players.

Ricardo’s HyBoost concept: a modified Ford 1.0-liter EcoBoost triple with stop/start, a belt starter-alternator, intelligent electrification, super capacitors and an advanced lead-acid battery, and both a turbocharger and a supercharger. It produces 160 hp, 207 lb-ft of torque, and fewer CO2 emissions than the naturally aspirated 2.0-liter it replaces.

Reduced weight, improved aerodynamics, decreased friction, and more efficiently sized vehicles will help automakers keep many of their current powertrains, but it is when standards demand a fleet average of more than 50 mpg that everything changes.

“As you get further on, 2025 and beyond, the engine is downsized again and more highly boosted,” says Brooks. “Expect multi-stage — twin, triple, even quadruple turbine blades — to get low-transient and high-transient performance. Plus, you will have energy recovery with two stages of electric boost, and switch between the two when needed to reduce pumping losses when you don’t need them. The excess then going into the batteries or super capacitors.” But the complexity doesn’t stop there.

“The real pie-in-the-sky stuff,” he continues, “is regenerative braking, minimized combustion and split-cycle engines where the engine is a generator ticking away in the background in conjunction with alternative fuel or battery technology.”

Brooks says Ricardo is investigating split-cycle engines powered by cryogenic fuels that cool the combustion chamber down to bring emissions near to zero. There’s even a study of using cryogenic working fluid that expands in the cylinders to provide mechanical energy. Says Brooks candidly: “There’s some interesting stuff going on, but even I can’t say that I understand it all!”

Undoubtedly, a lot of money is going to be thrown at these future powertrains, especially the engine block. High-pressure boosting will require a lot of strength in the bottom end to prevent the block from twisting and chucking pistons out its side. Energy recovery systems will be integrated into the transmission, eliminating today’s parasitic belts and drives, but requiring a complete rethink of the relationship between engine and transmission; the engine could become part of the transmission.

Looking like the business end of a rocket, Federal Mogul’s ACIS plasma ignition system promises to be a game changer. Expected to debut on high-end luxury and performance vehicles before 2020, it gives engine designers greater latitude with more complete combustion and far fewer engine-out emissions. It may even have a role in aftertreatment.

Tighter particulate matter standards will eliminate today’s tradeoff between NOx emissions and particulates, and be applied to gasoline engines as well as diesels. With some OEMs going for stoichiometric combustion, others for lean, and still others for HCCI (Homogenous Charge Compression Ignition), the question of after treatment of these gasoline engines becomes critical. Like a diesel, will they need a three-way catalyst, a particulate filter, SCR (Selective Catalytic Reduction) or a combination of technologies? According to Brooks, the answer is: “Probably.”

As B- and C-segment vehicles move from four- to three- to two-cylinder engines, the question of what happens to light-duty trucks pops up. “I think you could potentially put a 2.5-liter four-cylinder engine with 450 to 500 Nm (330 to 370 lb-ft) of torque in a mid-size pickup without an issue,” says Brooks.

“The problem is getting the low-end torque that you need for towing and commercial use. That’s where you struggle.” One solution is to add more speeds to the transmission, dividing the spread between gears each time the engine is downsized. Gearboxes with 10 or more speeds are on the table, and this will allow the engine to run in its most efficient range. “You want to calibrate the powertrain to run as much as possible in that range to get the best BSFC (Brake Specific Fuel Consumption) to hit your economy target in real-world driving, as well as on the test cycle,” he says.

Predictive software is another area of study that promises to grow exponentially as economy standards tighten. Says Brooks: “There will be a lot more predictive calculations made in parallel to try and mitigate what the driver is doing when he’s driving. I think this idea of a model running in parallel to the actual controller will be huge, and that alone may give us some breathing room in terms of how quickly this onslaught of technology will happen.” With systems becoming more complex and interdependent, the focus will shift from mechanical to computer control, and the code jockeys will rule the world.

However, what will this car of the future look like to the average consumer? Brooks has an idea. “I think you will have a combustion engine in there with a lot fewer cylinders. There will be a smartly integrated boost system or electrification system, a smaller fuel tank, and the vehicle will be lighter and possibly smaller. Chevy Suburbans will look different. They will be much more aerodynamic, have a smaller, highly boosted combustion engine with electrification on at least some models. The hood will be much smaller, and the power generation and storage systems will be integrated such that the components are placed for optimum weight distribution. Finally,there will be a huge passenger compartment with the running gear hidden away.”

But is this what people want, and can afford?

The View From FEV

FEV, Inc. the North American arm of the German engineering consultancy FEV, is located in the shadow of The Palace of Auburn Hills, home of the Detroit Pistons basketball team. Its president and CEO, Gary Rogers, has been personally involved in two of the National Academy of Science’s CAFE studies, and this gives him a unique perspective.

“I think the question of, ‘Is it technically possible to get 54 mpg?’ has been answered, and the answer is, ‘Yes’. The question, ‘Can we afford it?’ is another question entirely.” Affordability, Rogers says, encompasses both the OEM’s development costs, and the consumer’s ability to pay for the vehicle that results. It also brings up another question: “Do people want it?”

FEV's Gary Rogers has been here before, having been involved in two previous National Academy of Sciences CAFE studies.

“If we eliminated large cars and light trucks, and everybody had to buy an A- or B-segment car, we could get to a 54 mpg fleet average very quickly,” he says, “but that’s not market reality.”

Yet, the CAFE regulations stand as public policy that carries a penalty for not achieving the stated goal. Thus, automakers have to convince people to buy the products that result from meeting this objective. It is not helped by critics who assert that, over the past 15 years when CAFE standards were stable, the industry “tricked” an unsuspecting public into believing it needed horsepower, not fuel economy. Nothing, Rogers states categorically, is further from the truth.

“The reality in today’s world is that we are developing more efficient engines and, through that, we are getting more horsepower. The technology that we are using to increase the specific power of engines can, in fact, be used to improve fuel consumption. That’s where the downsizing strategy comes in.”

Employing a smaller, high-output motor to do the same work as a larger engine is not new. Getting it into production in a manner that is both affordable and pleasing to the average car buyer is, however. “My opinion,” says Roger, “is that there is still a lot to gain from the powertrain, but there is a limit as to how far we can go with conventional powertrains.”

Pushing this technology will require not just downsizing but turbocharging, direct injection, variable cam phasing, cylinder deactivation, stop-start, and transmissions with more ratios or CVTs. To get more means going further.

According to Rogers: “I think the future is going to be more about energy management. That means turning things on when you need them and off when you don’t. If there’s a way to store energy, like during braking, you do it.” The lengths to which suppliers, automakers and others will go to recover energy seemingly knows no bounds. “They’re even looking at things like a piezoelectric technology that turns heat from the exhaust system into electricity that can be put back into the battery where it can be used either to take care of the passenger or move the vehicle,” he says.

It also means adding capability with microprocessor and communication technologies. FEV recently acquired DGE, a telematics and infotainment engineering company in nearby Rochester Hills, Mich.

Today’s in-car information technology can only suggest alternate routes. In the future, they will include information about time and money saved, topography, and  provide information to a vehicle’s energy management system.

Just as delivery companies learned that it was more efficient to make three right turns, and keep moving, than to slog through traffic to make a single left, Rogers believes that advancements in communications, the mapping of traffic, and adding topographical data to the decision tree will greatly improve real world fuel efficiency.

For example, instead of having a hybrid’s engine start halfway up a hill, at a point that is least efficient, “[the vehicle] looks ahead and makes adjustments ahead of time so that you can charge the batteries most efficiently.” This same technology also can be used by non-hybrid vehicle to determine the best combination of items (turbo boost, gear, valve timing, etc.) necessary to reach the destination quickly and efficiently.

There’s no question that this technology will happen, and change the look and feel of our daily drivers. Despite the fact that the North American continent is, by conservative estimates using government figures, sitting atop 1.4 trillion barrels of oil and untold amounts of natural gas, and that we have seen a 16-year stretch of steady to gently declining temperatures in the face of rising CO2 emissions, politicians have decreed that fuel economy and emission standards must tighten dramatically.

This despite the fact that it will take anywhere from 15-20 years before the current fleet of vehicles is replaced by a new generation of CAFE-friendly cars and light trucks. Vehicles, it should be noted, that will reduce the revenues state and local governments currently collect from fuel taxes as less petroleum is sold for each mile traveled. And this is not to mention the job losses that could come from raising levels beyond what the market needs/desires.

Without a doubt, the technology to come is amazing, and engineers will work tirelessly to solve the problems they have been faced with — that’s what engineers do. The only question that remains is: “At what cost?”

The Virtual Driver