[apk919]

I've been trying to get real data on how much air actually goes through the intercooler on an Exige... I'm using a GPS to record position, and speed over time, and a datalogging weather meter to record air flow through the back of the intercooler (as well as temperature, humidity, atmospheric pressure, etc) over time.

I first calibrated my air flow readings by forcing air through the roof scoop and taking readings across the face of the intercooler. While the meter reads in fpm, given this calibration and the area of the intercooler you can then convert fpm to cfm (without getting into the nitty-gritty, multiply the fpm measurements by 0.4606 to get cfm).

I established a fixed "course", and gathered data with both the stock Exige S roof, and the Cup roof... processed all the data generating scatter plots, histograms, and linear regressions.

The bottom line is that there is no significant difference in intercooler airflow between the stock S roof and the Cup roof. How could this be? It seems that the inlet is not the limiting factor. Most of us have suspected the bottleneck where the end of the roof and the beginning of the clam meet is the limiting factor... my next step is to attempt to minimize the bottleneck and compare the results to the baseline.

First: a graph of vehicle speed vs. intercooler air flow speed, for both roofs, showing both the linear regressed results and the average value histograms.

The next two graphs are scatter diagrams of the raw data for each roof.