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Federal Mogul develops advanced aluminum piston for high-performance light-duty diesel engines

Federal-Mogul’s DuraBowl technology strengthens the crown of a piston, improving the aluminum’s strength where it is most needed. Click to enlarge.

Federal-Mogul Corporation has developed an aluminium piston that meets the higher strength and thermal performance demands of very high-power diesel engines. BMW is the first to use the piston in its triple-turbo 3.0-liter diesel (N57D30S1) engine applied in the M550d xDrive, with a specific power output of 93 kW/liter (124 bhp/liter).

The aluminium piston’s design uses the company’s DuraBowl process (earlier post) to create a reinforced combustion bowl rim to withstand the high mechanical and thermal loads. The thermal performance comes from a raised cooling gallery, made possible by Federal-Mogul’s development of a two-dimensional (2D) ultrasonic inspection process.

Federal-Mogul’s DuraBowl process re-melts the alloy around the rim of the piston’s combustion bowl, refining the aluminium’s microstructure and improving the fatigue strength of the material. To ensure control of key parameters, every bowl is tested using the company’s proprietary eddy current process, which detects imperfections below the metal’s surface.

The piston’s raised gallery places the cooling oil as close to the piston bowl as possible to achieve maximum cooling.

The cooler running of the piston enables durability and also reduces internal friction. This technology will play a significant role in enabling OEMs to introduce more efficient downsized diesel engines with improved fuel economy and CO2 emissions.

—Arnd Baberg, Chief Engineer Piston Product Engineering, Federal-Mogul

2D Ultrasonic Testing FINAL
Federal-Mogul's 2D ultrasonic inspection technique enables high performance pistons for diesel downsizing. Click to enlarge.

Positioning the oil gallery closer to the piston’s rim and bowl required a major advance in the precision and reliability of the casting process. Federal-Mogul has developed a new 2D ultrasonic inspection technique that has given the company a much deeper understanding of the process and tighter control of quality.

Standard, one-dimensional ultrasonic testing can identify defects but cannot quantify their size and position, said Baberg. The new 2D ultrasonic process provides 125,000 data points in 30 seconds. Using the technique, Federal-Mogul engineers can accurately determine the size and position of defects, providing valuable data for casting process development. The detailed information produced by the non-destructive test also ensures consistent quality in the finished high-precision components, he said.

Federal-Mogul validated the technology by dissecting and sampling hundreds of pistons, correlating the ultrasonic images against destructive testing methods. The research resulted in the development of software tools as well as a number of key physical parameters such as probe geometry, wavelength, beam geometry and focus.

Premium vehicle manufacturers are introducing higher power diesel engines that improve dynamic performance, CO2 emissions and fuel economy, but power outputs of more than 90kW/liter have long challenged piston designs, Federal Mogul notes.

Increasing the specific power output produces higher mechanical loads and temperatures, making a piston’s heat dissipation as important as its strength. Our aluminium piston can operate efficiently under higher thermal and mechanical loads than previously possible, without the risk of engine oil cracking and carbon deposit formation associated with a steel piston. By combining all our process and materials expertise, Federal-Mogul has produced an aluminium piston with the durability and the thermal characteristics that high-power diesels require. These advances mean that aluminium pistons can retain their leading position in diesel engines for light vehicles for some time to come.

—Gian Maria Olivetti, Federal-Mogul’s vice president for Technology and Innovation, Powertrain Energy

The piston was developed at Federal-Mogul’s center for aluminium piston development and production in Nuremberg, Germany.



Ideally, all reciprocating moving parts in ICEs should have minimum weight and friction to reduce wasted energy. Most current ICEs (after 120+ years of so called accelerated development) are not yet optimized with efficiency often under 30%.


Did you note that this is a diesel engine? I presume you refer to peak efficiency, since you have not stated otherwise. A “good” diesel engine has a peak efficiency of ~43%. I know of no automotive gasoline engine with peak efficiency less than 30%. Your statement “Most current ICEs… are not yet optimized with efficiency often under 30%” is way out of line. I think that you – deep down – know much better and therefore, you should stop posting comments like that!

Regarding the article, I would say that this is the absolutely last development step for an aluminum piston in diesel car engines. According to BMW they achieve a peak cylinder pressure of 200 bar on the 550d engine. Good – for an aluminum piston – and on pair with class-leading Mercedes 4-cylinder 2.1-liter diesel engine. Nevertheless, a steel piston can do much better. Steel pistons are already, since many years, “standard” in highly-rated heavy-duty diesel engines that achieve much higher cylinder pressures. Several piston manufacturers have developed steel pistons to a production-ready state although the comment from FM, “aluminium pistons can retain their leading position in diesel engines for light vehicles for some time to come” indicate that they might not be as advanced in this area as some of their competitors. If some of you wonder… yes, steel pistons improve thermal efficiency, especially on part load. Furthermore, regarding weight, a steel piston does not have to be heavier than an aluminum piston and friction is also somewhat reduced. It will be interesting to see which manufacturer is first in production with a steel piston in a diesel car engine.


Thanks Peter, a breath of fresh air, at the very least.


Thanks ToppaTom
If conventional engine developers are as stupid and stubborn as many on this forum seem to think, I wonder why the clever guys have not engaged themselves in this area for the last 120 years.

If we look deeper into the history records, we find that Rudolf Diesel advocated using cast steel as a material for his new invention, the diesel engine. In fact, this was one of the reasons why he was able to drag the large Krupp group (steel developer and many other things at that time) into diesel development. Eventually, casting steel for an engine block or cylinder head is very difficult – presumably more or less impractical. Eventually, the cylinder pressures were reduced from the levels Rudolf originally intended (practical engineers are sometimes more prudent than far-sighted scientists/inventors), so cast iron could be used until recently. However, cylinder pressures have increased considerably during the past years, i.e. up to the level that cast iron has difficulties to cope with the stress levels. Compacted graphite iron (CGI) has similar mechanical properties as steel but is easier to cast. CGI is frequently used in many new heavy-duty engines and in some passenger car diesel engine blocks. For pistons, however, forged steel is preferred over cast material due to the very small wall thicknesses. Nevertheless, CGI engine block and steel pistons go hand in hand (although aluminum engine blocks with cast-in steel parts can also achieve quite high pressure levels, as in the BMW case). One remaining bottleneck might be the cylinder head, where aluminum is still the preferred material for car engines. CGI is already used in heavy-duty applications also for cylinder heads.


Pxx....in the real world, very few ICE have an average efficiency of much over 30%. The average total drive train efficiency of our gas guzzlers is rarely above 18%. The 43% you referred to is often arrived at in testing labs at steady (ideal) speed and temperature without wind resistance etc.

What is even worse, is that the average total efficiency has not changed that much in the last 120 years.


Here are some of the real world results in passenger/mpg with 75% loading factor:

1. Passenger trains........... = 240 to 470 pmpg
2. Prius III.................. = 150 pmpg
3. Boeing 747-400............. = 68 pmpg
4. Airbus 380 ............... = 58 pmpg
5. USA fleet.................. = 39 pmpg
6. Large SUVs................. = 30 pmmg
7. Sirkowsky Helicopter....... = 15 pmpg
8. Bell 407 Helicopter........ = 11 pmpg
9. QE Ship.................... = 10 pmpg

Note: An old Ford Model T did better than current USA gas guzzler fleet. The rare real progress is with the Prius III, few PHEV/BEV and EU's small diesel



5) USA fleet is for ground passenger vehicles.


More interesting stats:

1. Ford Model (1908)... = 21 mpg
2. Big-3 new cars (1935) = 14 mpg
3. Big-3 new cars (1973) = 12 mpg
4. Big-3 new cars (2009) = 22 mpg
4a. USA fleet average (2009) = 16 mpg
5. Big-3 new cars only (2012) = 24 mpg
5. USA fleet average (2012) = 17 mpg

It seems obvious that no real efficiency progress was made in the last 104 years. USA would be better off driving 240 million 1908 FORD Model T @ 21 mpg than the current 17 mpg fleet.


@ HarveyD

What does engine efficiency have to do with wind resistance? Nothing!


I had a quick look at your data but find no reason to comment on them. They are simply off-topic. If you prefer to discuss average efficiency of an engine, why did you not make a list of average engine efficiencies instead? If you want to prove your point that engine efficiency – peak or average – has not improved in 104 years, you are in big trouble. Where can you find such data?


I am not old enough to have any own experience from the Ford model T. Instead, my first car was a Ford Cortina Mk II from 1968. On average, I could seldom get below 10 liters/100 km. Fuel consumption has been reduced by every car I have owned since then. Some data for the Cortina and my current car are shown below:

Ford BMW
Cortina 320d Touring
Unit MY 1968 MY 2008
Power (DIN) kW 47 130
Torque (DIN) Nm 116 350
Efficiency % 29% 42%
Weight kg 875 1580
Acc 0-100 16.9 8.1
Top speed km/h 139 228
FC l/100km 10.4 4.9
FC Gas equiv. l/100km 10.4 5.4

The numbers more or less speak for themselves. In 40 years, the fuel consumption has nearly halved (considering the difference in energy content between diesel and gasoline) in spite of much better performance and almost doubling of the weight. Safety, emissions and comfort are also substantially better for the newer car. I do not have any numbers on peak efficiency for the Ford engine but, most likely, it could hardly have been over 30%. Basically it would be up to the standards of HarveyD. Since the peak efficiency of the BMW engine is ~42%, the relative improvement would be ~30% (29/42). Note that the relative improvement in fuel consumption of the car is much greater, i.e. almost 50%. This indicates that other improvements (e.g. the car itself and its transmission) could be one explanation but we should also recognize that the relative improvement at engine part load would be greater than at high load, as one would expect for a diesel engine.


Apologies for the poor formatting of the table above. It looked O.K. before I posted the comment. I guess you can extract the numbers anyway...


O.K. let’s put your beloved high-tech Ford Model T engine in a modern car, such as, e.g. the BMW 320d Touring. First, you would notice that the 20 hp 2.9-liter 4-cylinder engine would not be satisfactory for modern customers. You realize that the engine would have to be up-scaled to obtain similar power as the 2-liter BMW diesel. This would be easiest and most straightforward accomplished by increasing the number of cylinder, i.e. by e.g. avoiding a reduction of the engine rpm that an increase in cylinder size would require. Furthermore, we know that the specific fuel consumption (g/kWh) would not be significantly altered if we just increased the number of cylinders and not the size of the cylinders. The largest practical V-type of engine for a car would be a V16 engine but this would not satisfy the power requirements. Some kind of a multi-bank engine or maybe a H32 engine (2 rows of 6-cylinders on each side in a flat configuration) would enable the power we need. Let’s consider a H32 engine with a cylinder volume of 23 liters, which would give us 160 hp, i.e. not too far from the BMW. Needless to say, this engine would be far too heavy and bulky to fit the engine compartment of any modern car but maybe we could just neglect this for the hypothetical comparison. According to Wikipedia, the Model T could achieve a mileage of 13 to 21 mpg, of which you chose to use the “better” figure. This is equal to 11 to 18 l/100 km, i.e. figures that seem plausible for a 20 hp 4-cylinder car of those days. I have not dared to conduct a drive cycle simulation on the H32 engine in the BMW chassis but I would presume that the 8 times larger engine could increase the fuel consumption by a factor of some 5 to 10 compared to Model T. That would give between 55 to 180 l/100 km if we just use the end points of each interval. When you compare this to the fuel consumption I get in my car, you will suddenly realize how much engine technology has improved over 104 years.


Peter_XX...efficiency can be expressed by how much energy (fuel or electricity) is required to move one average size person one Km or one mile.

A $250 Ford Model T could move four people 21 miles with one US gallon of 1908 rather low quality poor gasoline, i.e. equivalent to 84 pmpg.

Some 104 years latter, the current USA car and light truck fleet can only do about 81% as well with an average of about 68 pmpg with greatly improved costly fuel.

Overall efficiency has not been improved that much or not at all?

I know that you will claim that today's high price bullet muscle cars and light trucks can move people faster with more comfort etc but it comes with an added price that could also be thrown in.

Today, it is wiser to use the trains for much higher efficiency.

Tomorrow's electrified vehicles, with 120+ empg may come close to today's trains but I doubt that ICE machines will do it.


Added info:

The average yearly inflation rate in USA during the last 100 years is 3.2%. The Cumulative inflation for the same period is 20X. A ($250) 1908 Model T represents $5,000 in today's dollars.

Compared to an average unit price of close to $25K paid for today's fleet, the Ford Model T could, in acquisition price ratio only, be another 25000/5000 = 5 times more efficient than our average over priced muscle cars.

By the way, my grand father had a 2012 Model T, my father used it for his honeymoon trip in 1914. It was used on the farm (often as a tractor) for 25+ years and ended up being hoisted in the shed in the late-1930.s. One of my younger nephew restored it in the late 1990's. The updated, re-equipped, re-wheeled, repainted (deep burgundy), restored version is still running a few times a year and does about 28 mpg. I'm not so sure of the ICE exact vintage but he added a battery, alternator, starter and headlights kit to make it highway legal.

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