Our project car was put up...
Our project car was put up on the rollers at HiTech Motorsport, with Brian Ebert at the controls of the Autologic tuning software. HiTech's Dynojet setup was brand-new at the time. It's equipped with both the load control and air/fuel monitoring options. The air/fuel option is nice, as instead of just reading it off a display during the run, it is recorded with the other run data. This way, when you graph multiple runs, you can see just how the air/fuel ratio responded to tuning changes, and on the same screen you can see how those changes affected power output.
Before beginning the swap project, we went to HiTech Motorsport to get some baseline numbers with the 4.6. The only modifications to begin with were a K&N air filter and Flowmaster three-chamber mufflers. The mufflers are likely giving us no power, however, as the stock 2 1/4-inch tailpipes are currently stuck back in the outlets and welded in place. The project car has a 4R70W auto trans, and the horsepower and torque numbers fell in right where they should have.
Quite surprisingly, the air/fuel ratio was spot-on during the baseline runs, hovering right around 13:1 through the entire pull. We went back a couple weeks later with the 5.4 in place and running fine, but as you can see in the 5.4 baseline runs, the computer was in definite need of some help dealing with the extra cubic inches and airflow. The torque curve started out with some nice gains, but by 4,000 rpm it was falling fast and ended up well below our stock 4.6 baseline.
With the baseline recorded, Brian set to work seeing what he could wring out of it. The bigger motor was running somewhat rich with air/fuel ratios in the 12.3:1 range, so the first thing addressed was to get that back up around 13:1. Brian then straightened out the factory timing curve, and we began adding timing by changing the base number (similar to turning the distributor on a 5.0). Our motor ended up liking 14 degrees initial up top, but it made a bit more torque down low at 12 degrees initial, so the timing curve was reprogrammed to reflect that. Brian also turned off some of Ford's torque-management features and took away most of the tip-in spark retard to aid in throttle response. That last change didn't show up on the dyno, but it made a huge difference when driving the car.
After the tuning was finished, we had big gains all over the curves, but the biggest difference was in carrying the torque curve out further. From 4,500 all the way up to 5,750, we picked up around 30 hp just with the tuning. And instead of falling below the 4.6 baseline near 4,000 rpm, we now had solid gains all the way up to around 5,600 rpm. At that point there was just no getting past the extremely long runner length of the stock 4.6 intake. There are ways to get around that in the future, with either an intake or cam change, but we were confident we'd gotten all the power that was available without further modifications.
Click here for the Mustang 5.4L Engine Swap Dyno Chart