Hot, Hot, Hot: Plastics Handling the Under Hood Heat

Injection-molded intake air manifold/charged air cooler for a 1.5-liter engine made with a heat-resistant plastic that can withstand peak temperature of up to 250°C during operation.

Although the word diablo is Spanish for devil, presumably it is the environs that said creature lives in that is the context for the use of the word in the name of a polyamide 46 developed by engineering plastics company DSM ( Stanyl Diablo.

Consider: Stanyl Diablo OCD2100, which contains 40% glass fiber reinforcement and features a patented heat stabilizer, a stabilizer that the company’s David Lange, application development engineer, not entirely jokingly describes as being akin to sunblock, but in this case, rather than resisting UV rays, resists the effects of high temperature, is being used to make a combination intake manifold/charged air cooler for a 1.5-liter turbocharged engine.

The material is able to handle continuous-use temperatures of 220°C and peak temperature of 250°C.  That’s 428°F and 482°F.  That’s Hades hot.

This is an example of how engineered plastics are making their way under the hood for applications that are ordinarily made in metal.  And Bob Akins, vp of Market & Sales for DSM Engineering Plastics Americas, points out that engines are being downsized and turbocharged for fuel efficiency, which means they are running hotter.

One consequence of this is that the environment under the hood is getting elevated, which can cause problems for some polymers, as in as the packaging of engines under the hood are all the tighter in the available space, temperatures are rising, which presents challenges for some plastics as regards their thermal stability and oxidation.

So as indicated by those figures for the intake manifold/charged air cooler, the polyamide 46 in question can handle the heat.

Also, there has to be chemical resistance for the charged air cooler portion of the system.  While most intake manifolds have made a transition from metals over the past several years, they’re dealing with intake air while the charged air cooler is working with the gases from the turbo system, which is not only hot, but can contain corrosive materials, which makes chemical stability all the more important. 

However, there is another related concern for automakers, which is reducing the mass of their vehicles.  Obviously, a plastic replacement for a metal component wouldn’t necessarily be a good move if that meant a weight increase.

In the case of the intake manifold/charged air cooler, it weighs 40% less than a comparable aluminum part.

According to Satish Kantebet, sales segment manager, Automotive, DSM Engineering Plastics Americas, the company is working on developing replacements for many under-the-hood parts that have historically been die castings or stampings.

For example, the oil pan on the current Mercedes S Class is made with a polyamide 6, Akulon Ultraflow; this component is 50% lighter than a comparable metal part.

Another fuel-savings benefit that can be achieved by using plastics under the hood is realized through decreased friction.  By using Stanyl polyamide 46 (a non-Diablo version) to produce a timing chain guide, the reduced friction can, says Akins, result in a reduction of fuel consumption by as much as 1%.—GSV