616 - 94 Mustang GT
Engine Log History

This graph shows the Air Fuel Ratio of the Stock 5.0 (+ headers and without cats, high volume fuel pump (don't know the number off hand, but more than enough) pre-regulated to 38-40 lbs pressure, stock diaphragm regulator aft rail is still in place and operating.  (Injectors are red. ) with the Vortech Supercharger, providing 8 to 10lbs of boost.  As you can see, the mixture is very, very rich, to the point that my wideband logger is clipping in the rich direction, when the boost is on.  I am still trying to figure out exactly what is causing this condition.  One thought is that the MAS is being pegged by ~2/3 more airflow, causing the computer to clip, and basically turning on the injectors full open during boost situations.  

The graph below, shows a less throttle input lap, staying out of the boost  most of the time, and the computer seems to be working quite well here, as the AFR when not on boost is what I'd expect from a stock computer.  

Unfortunately, the car was purchased with the supercharger installed, so I am not positive what changes were made to accommodate the supercharger. From a quick glance, everything appears to be stock.  I am in the process of seeking this information from the previous owner.

Another graph (below) of Michael driving one lap, using the boost a little more.

UPDATE 11/05:

The graph below shows the latest state of tune for this motor.  It was found that the MAS was not able to keep up with the volume of air intake under boost.  The motor has since been rebuilt as a 331 with ported / polished performer Edelbrock 2.02" intake valve AL heads -  Motorsport F303 Cam and 42LB injectors - the same super charger and a C&L 76MM MAS unit.  The computer has been re-calibrated blind without dyno time - Results below:

UPDATE 3/07:

The car now has in Intercooler - everything else is the same.  With the same computer tune as above the car is now very rich, and very low on power.  The graph below shows one lap at Thunderhill.  Re-mapping of the computer is the next step.  Also, currently the IAT sensor is before the supercharger (next to the MAS - where it was before).  I believe this is most of the cause for the poor running. We'll likely put it after the intercooler.  Notice again, that my wideband 02 is clipping in the rich direction...  Boost measured is currently 7 sometimes 8 lbs max, although we are thinking of upping that another two or three lbs since we're going to have to remap the computer anyway.