Throttles go plastic

Until recently, one automotive component that has defied conversion to plastic has been the throttle body housing.

Over the past thirty years, automotive components made of metal have been replaced by plastic ones. Until recently, however, one component that has defied conversion to plastic has been the throttle body housing.

Now, engineers from MGI Coutier SA and BASF’s European Engineering Plastics business unit have developed two throttle bodies moulded from Ultramid, a nylon material from BASF.

Ultramid A3WG6, a nylon 66 with 30% glass fibre, has been used for the throttle body of the Renault 1.4 litre E7J engine in the Clio, Megane and Kangoo, while Ultramid A3WG7, containing 35% glass fibre, has been used in the PSA 1.7/2.0 litre EW engines in the Peugeot 307/406/607, Citroën Xantia/Xsara and in the new C5.

The Ultramid housing, chemically resistant to automotive fuel and lubricants, remains airtight across a temperature range of -40C to + 140C.

Like other parts, the plastic throttle body has a number of advantages over conventional alloy versions. The plastic part is cheaper to produce since it integrates many previously separate components into a single moulding, whilst weight has been reduced by 50%.

BASF claims that in the future, the nylon throttle system may be directly integrated into the nylon air intake manifold.

But is this a world first? Possibly not. The air induction system for the Rover K-series fuel-injected auto engines also made extensive use of engineering polymers, this time from Dupont.

In fact, Dupont claims that the Rover throttle body, moulded by Link Plastics of Telford, UK was the world’s first plastic component of its kind in volume production.

Both its housing and bypass valve are injection moulded from DuPont Minlon engineering thermoplastic resin, while the fuel rail and air intake manifold, manufactured by Manchester-based Caradon Rolinx, are made from DuPont Zytel PA 66 nylon resin. The manifold is a vibration-welded assembly of four parts.

Like BASF, Dupont claims that through the use of polymers, production costs are 30 to 50% lower than aluminium assemblies owing to the elimination of finishing steps and a more simplified assembly process; the Dupont throttle body weighs 40% less than an aluminium unit.