OVERVIEW

The never-ending pursuit for performance and efficiency within the automotive industry necessitates the need for increasingly advanced pistons that are both lighter and stronger than their predecessors. The speed of this rapid development trend has forced us into finding new ways to manufacture our pistons.  Traditional metal billets, forgings or castings are not going to cut it for high-performance engines of the future.

With the demand for high-level components, we have to ensure that our place at the top is backed up with state-of-the-art solutions. We are continuing to push piston innovation and manufacturing to improve the interaction with integral engine components, delivering vital performance gains for our clients in the automotive and motorsport sectors. This is where Materion steps in. Working in conjunction we are now producing and machining Metal Matrix Composite (MMC) pistons.

CHALLENGES

Traditional piston materials can only offer so much, the trade-off between weight and strength is the key limiting factor that determines engine performance. The lighter the components, the higher the engine speed, which increases the potential to produce power, however with increased speeds comes the need for increased strength.

These 2 characteristics do not usually go hand in hand, when weight is reduced it usually means the strength of components can become compromised when machining traditional billets. Therefore, to make additional gains in piston development we needed to find a material solution that yields and increase in strength whilst being lighter than the current materials in use.

We worked on a project in collaboration with NATEP and BRP Rotax with the aim to create a significant step change in lightweight, robust and high-performance pistons. This led us to using Materion’s SupremEX metal matrix composite (MMC) aluminium alloys to increase strength, stiffness and reduce fatigue to produce wear resistant pistons.

SOLUTIONS

The NATEP, BRP Rotax project gave rise to us forging a partnership with aerospace company, Materion. Their MMC alloy is exactly what we needed to push the boundaries of piston development and performance.

Materion’s SupremEX composite combines ultrafine silicon carbide reinforcement with aerospace grade aluminium alloys. The result is a composite that is superior to conventional alloys, combining the lightweight properties of aluminium with outstanding strength and stiffness. SupremEX pistons can be used to replace aluminium, titanium, steel and other structural alloys and composites. The specific stiffness of SupremEX exceeds that of other piston materials by at least 40%, allowing for significant reductions in reciprocating mass.

The reinforced structure of MMC pistons minimises wear at critical interfaces, compared to conventional aluminium piston alloys and offers a 25% lower coefficient of thermal expansion. This in turn allows tighter control of piston to liner clearance reducing piston slap, blow-by-oil carry over and crevice volume, providing increased efficiency. Higher working temperatures and combustion pressures can be achieved due to greater fatigue resistance (at running temperatures, more than double that of conventional aluminium alloys), with lower coefficient of friction and increased wear resistance contributing to improved combustion efficiency, brake specific fuel consumption and hydro-carbon emissions.

All of these factors ultimately yield an overall increase in performance and efficiency, allowing us to continue producing world-beating power units that find homes in cars such as the GMA T.50, with its ability to run at engine speeds in excess of 12,000rpm and the Lanzante TAG Turbo project, that has a rev limit of 9,000rpm, making these extremely limited engines the highest revving turbocharged powertrains used in a road legal car to date.