Performance data acquired from a full characterization test for several vane positions is plotted as the performance map shown here.  The broad range of high efficiency is apparent, as well as the areas of peak hydraulic efficiency.

The overall peak pump efficiency measured was 62% for this first prototype and it occurs near the 33% positive swirl vane position, which is in agreement with the performance map.

To achieve the optimal benefit of reduced parasitic pumping losses the design geometry of the impeller, vanes, and scroll for peak efficiency are laid out around the part-load operating point, where typically the engine operates most often (see figure 2).