What’s being done:

Following up on the prior days data logging with the Darintake modified airbox I drove today with the airbox taped up.

Results:

In the morning the results were (ambient temps rising from 76 to 81F):

In the afternoon the results were (ambient temp fluctuating between 86-88F):

Comparing the results from the Darintake logging with the sealed airbox logging produced the following charts, first the morning:

Here is a comparison of the afternoon results:

Finally, I looked at periods of rapid temperature rise, associated with periods where the car was slowing or stopped, and noted the start and end times of the temperature rise along with the amount of temperature rise.  From this information I calculated the increase in degrees Fahrenheit per Second for each configuration; the Darintake airbox and the sealed airbox.

Plotting the data samples for each configuration in increasing order produced the chart below:

If the average rise rate of each configuration is calculated, the results show that the sealed airbox enables the air temperature probe in the air filter to heat up 75% slower than the rate at which the Darintake modified airbox heats up.

Conclusion:

The Darintake may be a no-brainer modification to make to the stock B5 S4 airbox if the goal is to increase airflow through the airbox.  In fact prior airflow testing of the airbox in different states of modification illustrated the benefit of the Darintake for increased airflow.  But if keeping the temperature of the intake air low is the goal, putting holes in the airbox does not help the cause.

Future Investigation:

Based upon these results I am now curious about the potential benefits of a cold air intake, and whether they would be realized.