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1999 Mustang GT Modifications Upgrade
Don't Break The Bank When Upgrading Your Two-Valve Modular Motor.
Today, we all like to talk about budget, reasonable cost, and things that are flat-out cheap when talking in the aftermarket Mustang ranks. Unless you have been living in a cabin in Montana without contact to the outside world, it is no secret we are in the middle of a recession. But just because the state of economics is in limbo, it doesn't mean you cannot modify your Mustang and have fun racing it or ripping up the streets. There are some great cars out there-including the bevy of '99-'04 Mustang GTs.
Getting into a Two-Valve modular motor-powered Mustang is not hard these days, and they are pretty easy to modify, too. Thanks to New Edge Stangs hitting dealerships nearly a decade ago, the cars are well into their service life, and most have racked up quite a bit of mileage. That means, for a reasonable price, you could walk away with a V-8-powered Mustang in relatively good shape.
Kenny Miele of our Yo, Ken! column found out firsthand what a bargain high-mileage New Edge cars can be. He picked up his '99 Mustang GT a few years ago with 129,000 miles on the odometer. For the sweet price of $5,400, he walked away with a clean Mustang. Now this silver GT serves as his daily driver and he has run up the odometer to 160,000 miles while commuting to and from work. Thanks to regular oil changes and general maintenance, Miele has only had a small problem with a sensor for the A/C system. Past generation Mustangs would be ready for the scrap yard with that mileage, but not these mod machines. They are well built, sturdy, and high mileage shouldn't be a concern-provided the engine was maintained properly.
Last month we embarked on a mission to modify the sedate-looking Mustang. In the first installment, Yo Ken's Silver Stealth Stang received a complete Hotchkis suspension system upgrade along with Nitto tires and American Muscle wheels to help handle the corners better. Miele is a die-hard drag racer, but we told him the car would be more fun on the street. He reluctantly handed us the keys, but has since changed his tune. The car sits lower, looks better, and handles great. It was time to start upping the horsepower.
All too often, it is easy to throw on a centrifugal supercharger and get the thing tuned up to around 420-450 rwhp. However, not every enthusiast has several thousands of dollars lying around. That said, we thumbed through our big book of speed secrets to find parts that were more reasonably priced. Our first order of business was to free up the induction system to let the Two-Valve breath better. We opened the Summit Racing catalog and ordered two key components from Trick Flow Specialties, a Two-Valve High-Flow Upper Plenum (PN TFS-51811001) and a 70mm throttle body (PN TFS-24070). Summit has the plenum listed for $109.95, while the throttle body retails for $165.95 if bought separately. We prefer the black finish to the natural one, but the choice is yours as Summit has both colors listed for the same price. The combo package retails for a scant $250. That is almost a $26 savings with the combo deal.
Opening up the throttle body and upper plenum wouldn't do us any good if the area in front of those components were choked up. The stock air inlet was ditched in favor of the JLT Ram-Air Intake kit. The larger inlet tube, air filter, and shroud are well built and designed to eliminate any restrictions in feeding air to the throttle body. We re-used the stock MAF sensor housing, which attaches easily to the JLT inlet tube. The kit fits all '96-'04 V-8 Mustangs and retails for $185. The Ram-Air Intake is available in 15 different colors at an additional cost. Since we went with the black TFS plenum, we chose the standard glossy black finish for the JLT tube. TFS also sent us a set of underdrive pulleys to install while we were under the hood. I was personally disappointed that the pulleys do not come in black or silver, just blue. It is a personality trait of mine-I like to have stuff match, and the blue pulleys definitely do not go along with the other new parts. The stock valve covers are black, too, further nailing down our fade-to-black theme.
The fifth and final speed part to be added was a DiabloSport Predator tuner. We discarded the stock Predator tunes and had Craig Radovich of Radical Racing (Atco, New Jersey) custom tune the ECM. Radovich uses DiabloSport Chip Master Revolution software to modify the files. He kept ignition timing the same from the baseline runs to the modified dyno pull. The engine starts at 19 degrees on the low end and increases to 21 degrees towards the top of the run. Radovich also installed the parts at his shop, so we could keep our hands clean and work the camera.
Like all testing, we try to conduct before-and-after runs (be it dyno, strip, or both) for a true A-B comparison. We chose to perform chassis dyno and quarter-mile baselines for this test. The parts we were adding won't show a significant gain when comparing peak output between stock and modified, but the real-world performance is definitely there. The induction parts and tuning provide better average power gains, thus showing better results on the dragstrip than on the chassis dyno.
Miele showed up early to Radical Racing so the car could be cooled down before the dyno runs. Radovich opened up shop promptly at 9 a.m., and we strapped Silver Stealth Stang to the DynoJet chassis dyno. In completely stock trim, the car produced 220 rwhp and 247 rwtq. A few backup runs confirmed our baseline was indeed accurate.
The car was cooled off with a variety of fans and an open hood in preparation for our next baseline test-the dragstrip. Radical Racing is conveniently located one mile down the road from Atco Raceway, so that's where we headed. We want to send a big thanks to the Sway family for letting us pop in during the day to make a couple of runs. Radovich did a big burnout and heated up the Nitto 555 tires (non-drag radial rubber). The automatic GT left the starting line with a little tire spin but nothing that concerned us. It stopped the 60-foot clocks in only 2.11 seconds-not bad for a car with just 3.73 gears and a road race suspension. The scoreboard lit up with a 14.43 at 95 mph. Radovich's driving technique was to leave the shifter in drive, turn off Traction Control and Overdrive, leave off idle, and roll into the throttle.
With that, it was time to go back to the shop and swap the parts.
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.