If we want to know when MANN+HUMMEL started to develop intake manifolds, we have to go back to the middle of the 1980s. At that time, after dealing with the raw air duct, air cleaner and clean duct, we were considering the remaining area, namely the intake system which distributes air to the cylinders via the intake manifold.
The big breakthrough came when resourceful engineers at the Dunlop company started to manufacture their tennis rackets with a special new process. They used a zinc/bismuth alloy which melts at 170°C to cast a so-called “lost core”. Together with an injection moulding tool it was now possible to manufacture plastic parts with hollow areas. In the process, the lost core is overmoulded to form the plastic part and the core is melted out to form the lost core intake manifold. This gave us the technology to produce an alternative in polyamide for the intake manifolds which in those days were made in cast aluminium.
By November 1989 the development process was complete and the trade press was treated to a sensation. The first plastic intake manifold from MANN+HUMMEL went into series for use in the M50 engine of the day for BMW, a six-cylinder with engine capacities of 2 und 2.5 litres. In fact it was not the very first plastic intake manifold on the market as just a few months previously a sports car producer based in Stuttgart pipped us to the post with a small series. But in terms of mass production engineering we were in front with our product for BMW.
1991 saw the first plastic intake manifold with a resonance flap and a year later the first plastic intake manifold for a turbocharged engine rolled off the production line. In 1995 there was the premiere for the first variable-length intake manifold with rotary slide technology manufactured with the lost core process.
Today it all sounds so simple, but in those days these were pioneering developments. They led us to the production of the highly complex manifolds which we develop nowadays and which we wouldn’t have dared to dream about twenty years ago. At that time we had to pull generations of developers away from the development of cast aluminium and convince the engineers about the advantages of plastic. The first question was: “Will it even be strong enough?” or “Won’t it melt away?” That was real pioneering work.
How were we actually able to convince BMW in those days about the future of the plastic engine manifold? Our customer was firstly interested in the lower weight of the component, and also in the smooth surface in the area of the air pathways which was favourable for engine performance. Naturally other manufacturers got wind of the development. And the thinking was naturally that if a well-known producer is willing to replace the existing material of the intake manifold with plastic then it must surely work. In this way we triggered the first wave of plastic intake manifolds. Equally important were the lower costs. Apart from that the metal processing required for the aluminium cast product, such as the milling off of flanges or turning of threads, was no longer necessary.
The second wave with half-shell technology
Up to the mid-1990s the lost core intake manifolds were state of the art. Then the pressure to reduce costs led to the advent of half-shell technology. In this process the intake manifold is produced from half shells which are subsequently welded together using vibration welding technology. Today the use of multi-shell technology has proven itself where up to seven shells are welded to form an intake manifold. We presented the first plastic intake manifold in the world produced with multi-shell technology in 1995. Two years later the first plastic intake manifold produced with multi-shell technology was used for a turbocharged engine and also for the first intake module with an air cleaner and resonator. In 1998 rotary slide technology and electrical drive technology became integrated in the plastic intake manifolds using multi shell technology.
The big advantage of multi-shell technology is that it removes the need to melt down the core, a process which requires a lot of energy and is therefore relatively costly. On the other hand, the existing core technology enables the manufacture of very compact systems. For this reason a number of manufacturers have continued to use the existing technology. According to our information, the last line of this type is in our Ludwigsburg plant, but will be discontinued in the near future.
The multi-shell intake modules which we developed for the Audi V8 and V6 engines which went into series production in 2002 were a milestone. The V8 diesel intake manifold system is equipped with an integrated EGR cooler.
Then came the intake modules for the common rail engines of Volkswagen which were produced in a number of variations. You can read how this developed in part 2 of our blog on the history of the intake manifold.