Federal-Mogul claims high-temp piston novelty

Federal-Mogul Powertrain will unveil a novel design of piston at the forthcoming IAA show in Hanover, Germany in September. But production is five years away.

Federal-Mogel Powertrain (FMP), a division of Federal-Mogul Holdings Corporation, has developed what it calls a world-first in piston cooling technology by creating a sealed-for-life coolant chamber within the crown of its market-leading Monosteel heavy-duty diesel piston.

Branded EnviroKool, FMP says the technology allows pistons to run safely at crown temperatures in excess of 100°C higher than today’s limits, working where appropriate in conjunction with high oxidation-resistant steel alloys and protective crown coatings.

“Future diesel engines with more efficient combustion and greater specific power will have to run hotter combustion chambers, but engine manufacturers are constrained by piston crown temperature limits,” claims Gian Maria Olivetti, Chief Technology Officer, Federal-Mogul Powertrain. “EnviroKool enables higher temperatures without compromising the strength or durability of the piston.”

Delivering superior cooling efficiency with minimum weight, EnviroKool is the latest evolution of Federal-Mogul Powertrain’s well-proven Monosteel technology.

An integral cooling gallery is created within a steel piston using friction-welded construction and then filled during the manufacturing process with a high temperature oil and an inert gas, before being permanently sealed with a welded plug.

The EnviroKool technology has enabled Federal-Mogul Powertrain to overcome the temperature limitations of conventional open galleries that have to use engine lubricating oil as the heat transfer medium.

“The prolonged exposure of engine oil to higher temperatures in the piston oil cooling gallery leads to degradation and carbon build-up, reducing the cooling efficiency and leading to overheating,” explained Keri Westbrooke, director, engineering and technology, Federal-Mogul Powertrain.

“The superior high temperature properties of the EnviroKool gallery coolant allow it to handle increased gallery temperatures reliably, with the heat subsequently removed from the undercrown – where temperatures are lower – by a standard cooling oil jet,” he added.

With no build-up of carbon in the cooling gallery, heat dissipation remains unhindered for the life of the piston, it is claimed. The new technology is so effective that the oil cooling flow to the spray jets can be cut by 50 per cent, reducing work for the oil pump, lessening parasitic losses and improving engine efficiency.

The heat removed from the piston as a result of the spray jets is additional to that which is conducted away through the pin, piston skirt and ring pack.

Federal-Mogul Powertrain has already accumulated more than 1,400 hours of testing on heavy-duty engines fitted with EnviroKool Monosteel pistons. Development programmes are underway with several customers on engines scheduled for production launch within the next five years.

“EnviroKool is our latest in a succession of enabling technologies designed to help our customers produce engines and vehicles with a reduced carbon footprint, without compromising longevity, durability or performance,” concluded Westbrooke.
                          Why are these pistons needed today?

Asked to explain the need for such pistons these days, a spokesperson said: “To significantly reduce BTE, more advanced technologies are required. At this time, initial testing is indicating that waste heat recovery (WHR) appears to have the highest potential to fulfil these BTE expectations. Higher in-cylinder temperatures are desired to gain this significant BTE improvement. If higher NOX cannot be avoided, after treatment is needed to compensate.”

Asked how much more expensive will the piston be when it goes into production, the spokesman added: “The price of this new technology depends very much on the required level of the increased piston temperature, as well as the required engine volumes. Generic numbers cannot be shared at this time.”

Federal-Mogul Powertrain will present a range of heavy-duty diesel pistons at the IAA Show in Hanover, Germany, September 21-29, 2016. The company will exhibit at Booth C28 in Hall 13.

Those familiar with piston development may recall that attempts to mate ceramics with steel in piston construction go back many years. For example, steel pistons with ceramic inserts have been under development for at least 30 years with NGK issuing a patent in 1985.

But Wellworthy's interests in the UK go back even further. It published a patent in 1971 with respect to a piston with a ceramic insert, the object being to insulate the crown from the main body of the piston, thus attempting to save the piston from cracking and eventual destruction.

More recently, in 2007 for Audi’s diesel-powered cars at the 24-hour race in France, Mahle supplied pistons with a cooled ring carrier (proven extensively in passenger car diesel pistons), and a ceramic fibre reinforcement of the bowl rim. This allowed the pistons to withstand the extremely high thermal load at the bowl rim, without cracking, for the duration of the 24-hour race. The cast-in ceramic fibers considerably increase the load-bearing capacity at the bowl rim.

And for many years Mahle supplied ceramic-coated pistons for Ford 6-litre and 7.3-litre PowerStroke engines.