Muscle Mustangs & Fast FordsHow To Engine
1999 Mustang GT Modifications Upgrade
Don't Break The Bank When Upgrading Your Two-Valve Modular Motor.
Tuning and Results
For the record, the install was simple, easy, and can be performed in your driveway. Once the parts were installed, we moved the car back to the dyno. Radovich wrote a starter program, which included the same 19-21 degrees of ignition timing as well as some extra fuel due to the better induction. He made a pull and cut it short as the air/fuel ratio readings went super lean. A new program was written, and the Predator was used to install it in the ECM. Handheld tuners re-flash the factory computer through the OBD-II diagnostic port, usually located under the dashboard on the driver side. The re-flash takes a few minutes to remove one program and upload a new one.
The new program, with the extra fuel, proved to still be too lean. "I can't believe I had to add that much more fuel for this car," comments Radovich. A third tune was constructed, and this time the air/fuel ratio was just right (12.5:1 range). It was a little on the rich side, but Radovich wanted the car to be safe and not have any problems.
Peak power gains were not near what most would have thought, but the real story lies in the average gains. We saw a 5 rwhp gain and torque shot up by 22 rwtq. The best part of the dyno graph is the aggressive torque and horsepower curves from around 2,800 rpm to 4,100 rpm. At one point it was 32 rwhp compared to our baseline. Torque also saw serious improvements with 30-40 rwtq increases at spots on the curve. We really liked how much flatter and smoother the torque curve was on the final dyno run as well.
"Looking at the peak numbers doesn't tell the whole story. I wanted to do dragstrip testing because people forget that is where you want to see the gains. Too many people rely just on chassis dyno numbers and peak readings. Getting this car on the dragstrip is where the gains will be realized," comments Radovich. Our goal of getting after numbers the same day went in the garbage when we finished up too late to head over to the dragstrip. We messed up the basics of A-B comparisons by throwing a different variable-hotter weather.
Miele ran at Atco Raceway the following night during its regularly scheduled street night. Our esteemed column writer raced with a warm engine and still ran 14.31 at 96.8 mph. The weather was significantly warmer than the day before, and the car was run without the benefit of a cool down like our baseline. Nevertheless, it picked up over a tenth of a second and almost 2 mph. It was a little disappointing, but we are optimistic that getting back to the track will reward us with times somewhere between 14.18 and 14.22 at 93-94 mph. The mid-range gains were the primary reason for the drastic drop in elapsed time. Good thing we have another track day planned soon.
While we were mildly disappointed that Silver Stealth Stang didn't run quicker, we did effectively add more horsepower and torque, especially through the mid-range where the car needs it most. As the weather cools off, we are sure there are some days we might be capable of squeaking a 13.99 out of it, but for now we are happy with how well the shifts hit under WOT. Radovich has the transmission shifting smoothly and casually for around town, but go wide open and the car chirps the tires on the shifts. The car is equipped with a 4R70W transmission, which is computer controlled. Instead of adding a shift kit these days, making the trans shift firmer is done via the computer. Miele has reported the fuel economy seems to be better, too, although he didn't have any hard numbers to report.
Next month we'll open things up a bit on the exhaust side to help usher out the extra air we are letting in with the new induction components. We are also planning on getting a looser torque converter and aluminum driveshaft installed to help Silver Stealth Stang run down the quarter-mile quicker.