The sight and sound of Aston Martin’s exotic 600-kW (805-hp) £1.5M Vulcan thundering around the Paul Ricard High-Tech Test Track in the South of France is spectacular. But on board the supercar, out of sight and making absolutely no sound, is a modest plastic container that promises to bring a major advance in engine lubrication technology and servicing.
Developed by Castrol, the Nexcel oil cell is in effect a removable one-piece engine oil tank and filter that integrates with the powertrain. But there is far more to it than that. It delivers several significant benefits: a complete engine oil change in 90 s, reduction of friction losses, a “significant” cut in CO2 emissions, easy use of bespoke, precision-engineered oils to suit specific particular engines, and far better sustainability.
Its test program in the ultra-high performance and exclusive (only 24 will be built) Vulcan, is a demanding technology demonstration that is proving very successful, Castrol Nexcel Chief Engineer Oliver Taylor, told Automotive Engineering: “We expect to see production road vehicle installations in two to five years with high volume use following. Vulcan gets us onto the technology implementation curve.”
By 2020-25, he foresees a majority of cars entering production using the system. As well as the Vulcan's V12, Nexcel oil cells have been tested in a wide range of car engines.
OEMs like the concept
One challenge to be met is that the Nexcel oil cell’s capacity would typically vary between 3.0 L and 5.0 L on mass-production vehicles, causing potential engine-bay packaging challenges. But Castrol is working to design and engineer appropriate solutions. Also, ideally it needs to be integrated into the concept and initial design phase of a new engine (and probably vehicle) to accommodate plumbing and electronics as well as total space; attempting to adapt current high volume engines would bring manufacturing and cost hurdles.
But Castrol is highly confident of Nexcel’s future, reporting positive reactions from OEMs and engine manufacturers aware of the system.
“Nexcel is fully sealed and contains all the engine oil, and the filter. It simply clicks into place— and could mark the end of the traditional oil change,” explained Taylor. He said the idea for the project came from brain storming sessions within the company’s 50-strong, global innovation Ventures Dept. about four years ago. Design, development and engineering of the system, which he believes to be unique in the car industry, then centered mainly on the company’s U.K. facilities.
In a series-produced car, the Nexcel oil cell would be positioned in a “docking” area close to the engine block. The cell incorporates electronics which “shake hands” with the car’s CANbus and engine management system, while monitoring both the amount of oil available and its quality (ensuring its grade and specification are correct every time the car is serviced). It also estimates the oil's remaining useful life.
“This allows a new potential to guarantee ‘precision lubrication’,” said Taylor. “When the car’s scheduled service is started, ‘service mode’ is selected via an onboard menu and a small electric pump transfers oil from the bottom of the sump into the oil cell. That process takes about 30 s. When complete, the cell, which incorporates the filter, can be unclipped from the vehicle.
“A new oil cell containing fresh lubricant and filter is simply inserted into the docking position, the hydraulic lines are connected through mechanical dry-break valves on the base of the cell, one to the bottom of the sump and two to the oil gallery. And that’s it: total time taken, 90 seconds.”
Tribology simulations were key
The precision lubrication that the system facilitates is a very important aspect of its technology, stressed Taylor, because of its friction reduction/CO2 lowering potential: “OEMs are interested in the overall benefits the system brings.”
To gain a greater understanding of just what can be achieved by friction reduction, he has spent seven years studying, particularly through tribology simulation, how lubrication systems can help deliver much improved fuel economy.
“Engines are of many designs and in them we find different surface finishes, materials, and types of bearing, all of which interact with engine lubricants in various ways," Taylor explained. "To generate the lowest friction possible for a particular engine we need hyperspecific lubricants tailored to specific applications and duty cycles in order to unlock further CO2 improvements.”
Thermal management also supports lower emissions. The electric sump pump can be used to ensure that when started from cold there is a precise amount of oil (the minimum safely needed) in the engine, while the remainder is in the cell. That ensures the engine oil and its systems heat up more quickly than usual; as Taylor noted, "a warmed-up engine is an efficient engine.”
The system works with both regular and dry-sump engines; the Aston Vulcan has a dry sump.
At present, Taylor is cautious about defining the CO2 improvement but says it is “statistically significant.”
To provide a high level of sustainability, Castrol is developing a system that will get the cells to and from service or consumer outlets. A reverse logistics model will be put in place to deliver new oil cells and collect used for reprocessing to achieve what Taylor describes as ‘virgin’ quality for re-use in similar engines. The cell is taken apart, cleaned, fitted with a new filter and refilled and dispatched again “a number of times.”
Nexcel facilitates oil being segregated and collected into specific viscosity grades "far more efficiently than is generally the situation at present,” he said.
Rigorous test regime
Will Nexcel add cost for the end user (vehicle owner)? Taylor stated that most new technology does add capital cost but that it is offset by increased efficiency.
Castrol’s design target for Nexcel is also for it to involve no more expense than a normal oil change service cost, with the added benefit of freeing up vehicle hoist requirements.
Testing in the Vulcan is one of the last stages of Nexcel’s development. Using it for such a small production run (24 units) is allowing very close monitoring by Castrol and Aston Martin.
And David King, Aston’s Director of Special Products and Motor Sport, said that as the Vulcan has a dry sump lubrication system, it was just a matter of replacing the oil tank with the Nexcel oil cell and doing some plumbing and hooking up to the CANbus. And it would provide a very tough test regime.
"We wanted to make sure the Nexcel system would work in every extreme environment we could put the car through," King said. "These included oil handling under extreme g-forces on the track; the effects of very hard acceleration and deceleration (up to 1.8g), of vibration and aeration — and the high flow rates put through the Nexcel oil cell from a highly specified dry sump system.” Flow has been tested up to 600 L/min, 10 to 20 times that of a typical regular car engine.
The real world on-track testing came after extensive laboratory simulation of g-force effect, durability testing and comparison with a regular system. Said King: “We demonstrated at least equivalent — and in many cases superior — performance with the Nexcel oil cell. We would not be using it on Vulcan if we did not think it had serious potential to put it on higher volume cars in future. I think it’s a fantastic piece of technology and we are first to market with it!”
So now almost everything about the 320-km/h (200 mph) Vulcan is about speed and efficiency — including changing its oil.Continue reading »