Automobile makers are constantly trying to improve the torque they can obtain from their engines, so that they can reduce engine capacity—and hence fuel consumption—without loss of mechanical performance. Their strategy includes reducing frictional torque—the negative force caused when a rotating object moves against another surface.

Part of the frictional torque arises in engine timing systems when the timing chain moves over an element that keeps it under tension. This chain tensioner is often injection molded in polyamide 66, but increasingly this material is being replaced by DSM’s Stanyl PA46, owing to its improved performance, both in terms of mechanical properties, as well as its frictional and wear characteristics.

DSM has continued to work on developments to improve the properties of Stanyl PA 46 for use in chain tensioners. Stanyl HGR1 and the next generation Stanyl HGR2, which will be introduced soon, offer further enhancements in friction reduction. Testing has shown that chain tensioners in Stanyl HGR1 produce lower frictional torque than any other material at relatively low engine speeds ranging from idle to 1800 rpm. HGR1 also performed well at vehicle cruise speeds.

By substituting PA66 with Stanyl HGR1 in the timing systems chain contact surfaces, frictional torque can be cut by 0.65 N·m. This equates to a fuel efficiency improvement of over a mile per gallon (over 0.4 km/L) over the drive cycle; that’s a substantial amount!

—Bill Burnham, DSM Business Development Manager

In comparison to PA66, Stanyl HGR1 delivered 10% lower frictional torque within the critical engine speed range between 650 and 1800 rpm.

Stanyl HGR1 polyamide 46-based material has already made its market debut on the latest version of the Pentastar V6 engine, built by Fiat Chrysler America (FCA) and fitted to numerous vehicles. The new material reduces frictional torque in the Pentastar engine timing system, helping reduce fuel consumption in a highly cost-effective way.