IAA 2015 - ACAD spurs on the lower engine speeds

IAA 2015 - ACAD spurs on the lower engine speeds

Three-cylinder and four-cylinder engines with a turbocharger in particular can expect more power by modifying engine resonance. 

The ACAD, active charge air duct or active charge air line, boosts the specific torque and engine output. For this purpose, plastics specialist MANN+HUMMEL has harnessed the energy of dynamic pressure waves. The module offers a cost-effective solution for car manufacturers, helping them to unlock extra performance from both large and small engines in the lower engine speed range. Thanks to the optimum configuration of the pressure waves in the section between the charge air cooler and the inlet valve, it is possible to increase the torque by over ten percent.

And this is how the newly developed module works: ACAD optimizes the path of the airflow between the charge air cooler outlet and the inlet valve downstream of the intake manifold. A rotary valve switches between two pipes of different lengths and does so with a minimal loss of pressure. The short line with a large diameter increases power output, and the longer line with a smaller diameter improves torque in the lower engine speed range.

Exploitation of physical options

At low engine speeds, the air mass can be increased thanks to additional pressure waves occurring just before inlet valve closing (IVC). At higher engine speeds, maximum power output can be increased by further reduction of pressure loss and allowing a maximum air mass to be trapped in the cylinder.

ACAD uses pressure waves to improve engine efficiency, thereby achieving a twofold benefit: the response characteristics at low engine speeds (torque increase) are improved and at high speeds, power is gained due to the short line with a low pressure loss. It is also possible to adapt the turbocharger map using these new torque and performance characteristics. For example, a smaller turbocharger can be installed, thanks to downspeeding thereby reducing the CO2 emissions of the vehicle.

One size fits all

ACAD is quite an all-rounder, as the module can be installed in turbocharged gasoline engines and in particular, in diesel engines where we have no issue with knocking. ACAD optimizes the performance of four-cylinder engines, and also of heavily downsized three-cylinder turbocharged engines. We can easily adapt the geometry of air intake systems to gain further benefit from resonance charging of three-cylinder turbocharged engines. In any case, torque is always improved throughout the entire engine speed range.

How the individual modules will actually look depends on the installation space requirements of the relevant car model. This cost-effective and lightweight component can therefore be used in virtually any vehicle. Thanks to its favorable price/performance ratio, it is recommended especially for small and medium sized cars from all automobile manufacturers.


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