Back from the dyno, made 5 passes on the dyno. We had to adjust the idle mixture and low speed transition because the GT500 MAF intake area is so large that it was quite sensitive to MAF adjustment with the low volume of air required by the 4.0 at idle. The good news ... produced 358.6 RWTQ at about 3750 RPM. The HP peaked at 296.5 RWHP at about 4750 RPM and then we reached the max for the fuel pump and it started to go lean. I knew that was going to happen because I did not get time to rewire the pump with #10 wire from the fuse panel (stock wiring is only like 16 or 18 gauge) ... thought I might get by for this morning, but ... Have to go back next weekend. I am going to increase the pulley 1/4" to bring the boost down a bit, I hit 16.2 pounds of boost and I want to keep it at a max of 14 pounds. The tune made a huge difference in performance and drivability, that GT500 MAF is huge and although it fixed my issue of maxing out the stock GT MAF, it required a lot of tuning to get the fuel trim right. That old saying ... "torque is king on the street" ... is true. From 2000-4000 RPM the Mustang accelerates unbelievably strong. The 100 mile drive back from Birmingham was another thrill ride and you can feel the extra torque from the M122 blower. So, this week I will rewire the fuel pump, put on a slightly larger pulley (1/4") and schedule another dyno run. I probably don't really need it as the fuel trims have all been adjusted and should be OK once I get the heavier wiring to the pump, but it is always great to see the real numbers. My buddy says minimum 325 RWHP when I get the pump wiring fixed.
