The potential crossover of technology between the racetrack and the road almost invariably involves mechanical systems or processes, but a low friction oil developed for motorsport applications could provide a cost-effective reduction in the CO2 emissions of road cars.
Created entirely in-house by U.K. specialist oil developer and producer Millers Oils, Nanodrive is a family of fully synthetic lubricants containing nanoparticles.
Independent back-to-back tests using a Porsche 911 race engine showed an immediate power gain of more than 5% by replacing a top conventional synthetic lubricant with Nanodrive oil of the same viscosity, said Millers Oils’ Technical Director Martyn Mann. “In motorsport, lower friction means quicker lap times, and reduced wear means fewer costly engine rebuilds. In the road car industry, engineers are continually trying to improve engine efficiency through developments such as smaller bearings and low friction rings and cylinder liners. Nanodrive contributes to each of these requirements without needing any design modifications or changes to manufacturing,” he said.
Mann states that use of Nanodrive can immediately provide, at minimal cost, the level of efficiency improvements that would normally involve engine modifications. And it has the potential to be used in all automotive applications regardless of performance or technology levels.
Engine friction arises from two primary sources: viscous losses and boundary friction. Viscous losses occur wherever a lubricant flows, due to shearing between adjacent layers of the oil. Explained Mann: “To reduce the effect, engine manufacturers specify ever thinner grades of lubricant—replacing an SAE 5w30 multigrade oil with a 0w20 grade has been estimated to give a direct improvement of 2% in fuel consumption.”
There is a downside, however; reducing viscous losses by using thinner oils risks increasing boundary friction and reducing engine life through increased wear. Boundary friction occurs where the oil films are so thin that opposing metal surfaces begin to interact with each other.
Mann adds that these conditions exist between piston rings and cylinder bores as well as in the crankshaft bearings as they begin to rotate during engine start-up.
As more vehicle manufacturers introduce stop-start technology, start-up conditions will occur much more frequently—from an average of around 40,000 times in a lifetime to a likely 1 million.
“Millers Oils used nanotechnology to create a combination of low viscous friction and reduced boundary friction,” said Mann. “Proven in their range of transmission lubricants that won the World Motorsport Symposium’s Product Innovation award, the technology has now been further developed to provide a family of race engine lubricants.”
Now a Nanodrive variant for high-performance road cars is in development.
Full details of the chemistry involved remain confidential, but it centers on what the company describes as “the exceptional reactivity” of the nanoparticles used in the formulation.
Mann is confident of the significance of his company’s development: “The particles we use have some very special properties that make them uniquely useful as lubricants for extreme conditions. As the contact load between opposing engine parts increases, reactions between the particles and the metallic surfaces actually lead to a reduction in friction. Another useful property is the way the nanoparticles nest around each other, like the layers of an onion, able to peel off under pressure, shedding a slippery, protective film over the metal surfaces to reduce friction and wear.”
In comparison tests with conventional boundary lubricants such as molybdenum disulphide, conducted at Millers’ U.K. R&D center, Nanodrive lubricants are reported to have reduced friction by up to 25% while increasing load capacity by up to 80%.
A typical test to compare the sliding friction performance of different lubricants involves a high-frequency reciprocating rig in which a steel ball is loaded against a reciprocating plate. In a test for a Formula One transmission application, the ball was loaded at 4 gigapascals (approximately twice the service condition) while the temperature was increased from 40°C (104°F) to 160°C (320°F) at 3°C (5.4°F) per minute.
Outlining the results, Mann said: “The friction coefficient of a standard road car oil was 0.17, and the average film strength (measured by electrical resistivity) 84%. A race oil from another manufacturer showed friction of 0.11 and film strength around 75%.
“A competition oil from another brand showed friction below 0.1 but highly variable film strength, averaging 34%. Another race oil showed a drop in friction above 140°C, meaning that any benefits are restricted to extreme temperature conditions.”
Millers current triple ester synthetic oil showed a good friction figure with a film strength of 98%, but the new Nanodrive oil of the same viscosity recorded a friction value that began to drop away from around 75°C (167°F), falling to 0.06 while retaining a film strength of 98%—halving the friction without losing any film strength, Mann said.
“The power gained by cutting frictional losses was independently demonstrated in rolling road tests on a Porsche 911 RSR,” he explained. “With a conventional 10w60 grade race lubricant, the car produced 200 kW, measured to DIN70020. On replacing the engine oil with Millers CFS 10w60NT Nanodrive, the result was 211 kW, an increase of 5.6%.”
The price of Nanodrive oils is about one-third higher than those of conventional synthetic lubricants, which the company regards as providing extremely good value-for-money power gains. The improvements are coupled with corresponding CO2 reductions, which indicate the potential of nanotechnology not only for high-performance road cars but also for a widening spectrum of road vehicles, including those with downsized bearings that are fitted with stop-start systems, where an immediate drop in CO2 is required.