A new engine program at Fiat Chrysler reveals an innovative way to solve the task of creating an advanced new material to improve engine efficiency and reduce vehicle weight.
The automaker enlisted the help of engineers at the federal Oak Ridge National Laboratory in Tennessee.
Material development is usually the stuff of advanced research — the sort of work that r&d departments might spend years toiling away at with little profit-making result.
For FCA's project, engineers have been able to bring a new grade of heat-tolerant aluminum alloy to market faster by taking advantage of research already being done by government scientists at Oak Ridge.
It's rare when a government-funded initiative makes its way into a commercial engine.
The new alloy was borne out of a project that used Oak Ridge's Titan supercomputer and included Fiat Chrysler engineers and casting experts from Nemak North America, the giant Mexico-based supplier of engine blocks and cylinder heads.
Engine designers have always known that improving an engine's thermal efficiency — the amount of energy contained in fuel that is converted to work — is one major key to extracting more power and fewer emissions from a motor.
Most of today's mass-produced aluminum cylinder heads are made of what are referred to as 319 and 356 grade alloys, which start to weaken and distort at combustion temperatures up to around 390 degrees Fahrenheit. There are grades of alloy that can withstand higher combustion temperatures without damage, but they are expensive and can be difficult to cast.
The collaboration of Oak Ridge, FCA and Nemak engineers started in 2014 under a $3.5 million Department of Energy Cooperative Research and Development grant. It resulted in a new aluminum alloy that will allow engines to run about 180 degrees Fahrenheit hotter and can be cast on existing production machinery.
The implications are significant.
Hal Reisiger, CEO, Cosworth Group Holdings
572 degrees
The new alloy, called 16HT, raises the operating threshold to 572 degrees Fahrenheit. FCA estimates the new alloy will cost only about 7 percent more than 319 and 356 alloys. There is no estimate yet of how much fuel efficiency will be improved. In fact, FCA has not even announced which of its engines will first use the new alloy.
But the first application likely be a hard-working downsized turbo four-cylinder that would replace a larger engine in a heavy vehicle.
Fiat Chrysler has a 2.0-liter turbo launching now in the redesigned Jeep Wrangler. In a blog posted recently on FCA's media site, the company says the new alloy is at least a few years away from production. But about 100 prototype cylinder heads cast by Nemak are now undergoing testing at FCA.
Amit Shyam, Oak Ridge's lead researcher on the project, says the new alloy could be used elsewhere on engines, perhaps replacing heavy cast iron exhaust manifolds or in turbocharger housings. But cylinder heads are likely the first use because the benefits are largest.
"Cylinder head alloys are the most demanding application in an engine if you consider the fact that the casting is smaller than the cylinder block, but more complex because other parts are attached to it," he says. "It's more demanding from a thermal-mechanical aspect as well. The head sees many thermal cycles. If that was solved, it would be a very major advancement for better engine materials. So, that's why we focused on cylinder head alloys for initially lighter-duty automotive engines."
The big brain
FCA engineers credit Oak Ridge's Titan supercomputer with playing a big role in the breakthrough.
Titan, the third most powerful supercomputer in the United States, used a predictive development process known as an "ICME" — short for integrated computational material engineering. It virtually created about 50 alloy blends.
The computer was then programmed to "test" the heating and cooling characteristics of the virtual metals. The seven blends with the highest potential were then subjected to more stringent testing.
"The Titan and ICME let the team focus only on truly promising candidates instead of spending time on trial and error," Gregg Black, a senior manager in FCA's advanced powertrain engineering said in the blog post. "It's like Star Wars stuff for us, creating new alloys in the computer without having to pour it."
That's where supplier Nemak comes in.
The company, ranked No. 52 on Automotive News' list of the top global parts suppliers with annual sales of $4.5 billion, is a major supplier of cast engine parts to nearly all of the world's major automakers. Nemak also makes expensive low-volume castings from an alloy known as R350 for several manufacturers of high-end vehicles.
Nemak engineers brought a sample of R350, which Oak Ridge examined down to the molecular level to understand how the metal could withstand high heat without cracking, tearing or deforming.
"We spent a lot of money in the first 18 months trying to understand what makes R350 work, and what we found out is that we could make R350 do what it does without the expensive elements," says Shyam. "It was not the nickel and cobalt in it that everyone thought made it much more temperature resistant. It was some of the other elements that were there in smaller amounts."
Shyam said researchers using powerful electron microscopes studied the atomic resolution of the alloy in cross sections of areas known as precipitates, or the strengthening elements. From that, Oak Ridge was able to develop the 16HT alloy so that it was able to be cast.
Jose Talamantes-Silva, Nemak's research and development manager, said one of the major requirements of the project is that 16HT had to be castable on existing production machinery, a requirement that would save millions of dollars in tooling costs.
But the new alloy yielded another bonus: It proved to be a drop-in replacement for today's alloy.
"The same components can be used," Talamantes said. "In the current testing we are doing with FCA, there is no need to change any of the components.
"That means existing gaskets, valve seats and guides, camshafts and seals used on today's heads can be transferred to heads cast in the new alloy."
It also saves millions in product development costs. Talamantes says Nemak is meeting with FCA almost weekly to share data on how the heads are performing, and he expects engine testing to be complete by December.
Tightening global emission regulations could see the new alloy replacing the existing blends, and once volume rises, Talamantes says, cost will come down.
Material revolution
Executives at other suppliers say thermal efficiency gains in innnovations such as the new alloy shows there are still improvements left to be wrung out of the internal combustion engine before it gives way to the electric motor.
"If you look in broad terms, our engines, the ones we've recently developed, have about 38 percent thermal efficiency, some of the highest in the industry," says Hal Reisiger, CEO of Cosworth Group Holdings.
"If you can get to 40 percent — which we will — you are as efficient as a fossil fuel-fired power generating station which is used to charge an electric vehicle," he added. Cos-worth, the British firm best known for building high-performance engines, recently opened a new North American headquarters in suburban Detroit.
At Tenneco, a supplier of exhaust system components, such as catalytic converters and mufflers, Chief Technology Officer Ben Patel says the industry is in the midst of a "material science revolution that could change every part of the car in the years ahead."
"When you are dealing with emissions, heat is your friend. Whether it is a catalytic converter or an SCR diesel catalyst, the chemical transformation you are trying to enable all happens faster the hotter it gets," he says.
"Twenty years from now, maybe even less than that, there will be a whole new range of materials on vehicles that do not exist today."
New alloy
The new Oak Ridge alloy is one of those materials. Today's alloy cylinder heads rely on silicon as the strengthening component. But the lab researchers discovered that copper can take the heat without deforming.
"When we focused on copper, other people in the industry almost laughed us off, saying we'd never be able to cast that," FCA's Black says. "We knew there was competition, including other teams working at Oak Ridge National Lab, but we outperformed everyone on this."
The project yielded four patent applications, that when approved, will be owned by Nemak, FCA and Oak Ridge National Lab.
Shyam says about 35 people from all three organizations worked on the project, each bringing their own expertise.
"It was a highly collaborative effort. Nemak is very good at foundry-related issues and castings, what can and cannot be done in the foundry production process. FCA is very knowledgeable about what happens when you are running an engine, what can happen and what is needed from the alloy. The criteria that will make it successful. We were able to bring a lot of our fundamental ally design expertise. We were able to bring some of the best characterization tools available to bear on this problem."
Shyam acknowledges that it was a bit of a long shot developing the new alloy.
"We took a somewhat risky approach to understanding mechanistic approach, not confident when we started," he said.
"We do think there will be a lot of internal combustion engines that will be made in the coming years, and if we are able to contribute to the efficiency of those engines, that's what you dream of doing as an applied researcher in the national labs."