KJ Jones Senior Technical Editor
January 4, 2007
Photos By: KJ Jones

Horse Sense: Horsepower is our business. Well, it's actually just one facet of our business, but it's probably the aspect we dig the most, especially when we're talking about how to make more and the 'Stang or engine we're working is "bone stock." For this exercise, we're definitely not talking about any bone-stock Mustang.

With Ford's '07 Shelby GT 500 now officially out, and dealers are raking in major coin for them ("average" above-sticker prices are said to be in the $70,000 range; some Shelbys reportedly purchased for as much as $90,000), we've been watching the roads in Southern California to see whether enthusiasts who purchase the 500hp mega-Mustangs are actually driving them, or if they're immediately stowing the cars, hoping that a grand payday at the Barrett-Jackson Auction is in their future.

We're happy to report that while Shelbys may not be as dime-a-dozen as Foxes or New Edge 'Stangs, several of these special-edition, blown, 5.4 models have been spotted in the Los Angeles area. It also appears that owners have been quick to personalize and modify them.

Galpin Auto Sports, aka GAS (a division of Galpin Motors) of Van Nuys, California, is the newest player in dealership-operated, high-performance upgrade centers for Mustangs and other Fords. When we decided we wanted to be one of the first magazines to take a stab at upgrading a GT 500 for more horsepower, we contacted Steve Carpenter at GAS because we knew he could produce a Shelby for us in a short timeframe. In less than two hours, Steve had us on the phone with Tom Pence, the owner of the black and silver-striped GT 500 you see in this report.

Tom is the kind of enthusiast we love. After detailing our intentions and assuring him our upgrades would in no way prevent him from returning the car to stock trim at any time-we're betting he won't-Tom gave the OK for Galpin's technicians to install a Lightning Force Performance Stage 1 Power Package (PN Shelby Power Pack; $469) on his brand-new ride.

LFP's entry-level upgrade for Shelby 'Stangs includes one of two interchangeable Quick-Change billet-aluminum upper pulleys (2.80- or 2.60-inch) for the blower, a high-grade-steel mounting hub, and Allen-head fasteners. A machined idler pulley of 100 mm is also included (for the 2.60-incher only) and provides increased tension on the Shelby's wide belt to ensure it stays secure when the supercharger is at full whine. Aftermarket belts for the GT 500's supercharger were not available at the time of our test, but LFP says it should have 10-rib, poly-cog-style belts in stock by the time you read this.

Increased boost (as much as 4 psi with the 2.80-inch pulley and 6 psi with the 2.60-incher) creates increased cylinder pressure and heat and changes the engine's air/fuel ratio dramatically. To compensate for this, each Stage 1 Power Package includes SCT's XCalibrator 2 handheld flash programmer, loaded with a custom tune created by Andre Terranova of Custom Performance Tuning in Houston, Texas.

Spark is also a big concern whenever boost increases, so we're installing a set of high-output coil packs and coil-on-plug connectors by Lightning Force Performance. The coils increase spark plug voltage, which keeps the flame of combustion lit under higher boost conditions.

Of course, none of this is being done simply for the sake of doing it. Our primary mission is to obtain data-in this case, horsepower, torque, and boost-and the best way to do it is by giving Tom's Shelby GT 500 a good workout on the Dynapack Evolution 4000 chassis dyno at Extreme Automotive, once the pulleys and tune have been installed.

What were the results? Well, the Shelby GT 500 is already no slouch in bone-stock trim (the "500" in its name represents 500 flywheel horsepower). We know you're asking, "How much better-or worse-does this Four-Valve 5.4 become when influenced by a simple bolt-on and some computer technology?" Read on.

Here's a look at the brand-new (only 15 miles), bone-stock bullet in Tom Pence's new Shelby GT 500. While we're only swapping out the stock 3.00-inch upper pulley, ignition coils, and revised Silver Oak programming, we think the upgrades should add quite a few additional horses.

Lightning Force Performance offers this easy-to-install Stage 1 Power Package for '07 Shelby GT 500s. We're using the 2.80-inch replacement upper pulley and steel hub shown in the photo, but a smaller, 2.60-inch piece is available. SCT's XCalibrator 2 programmer and LiveLink/LiveUpdate software are also included as part of the package. A billet-aluminum, CNC, 100mm idler wheel is provided with the 2.60-inch upper pulley. This larger idler wheel reduces belt slippage when the smaller upper pulley is used.

Also shown, but sold separately, is LFP's Pulley Puller ($89). This makes quick work of removing the stock piece and installing the hub.

The crew at Galpin Auto Sports is handling all the mods being made on this new 'Stang. Lead technician Axel Chinchilla begins this segment of the project by removing the stock Autolite Platinum spark plugs and regapping them to 0.028 inch.

Closing the gap on the factory plugs works for this upgrade, as the 2.80-inch pulley increased boost more than 2 psi. We're using LFP's high-output coils, which should keep the spark hot throughout the combustion cycles.

LFP coil-on-plug connectors ($399) feature stainless-steel connector cables and snap-lock spark plug connectors. We're using the LFP coil packs and connectors because they increase voltage to the spark plugs by about 25 percent, which is more than sufficient for the GT 500's enhanced power-adder.

Axel uses a small pick tool to extract each coil connector plug from the wire harness and turns each plug 360 degrees. He reconnects the plugs to the harness to achieve reverse polarity. This is a critical step when installing high-output coils on a Four-Valve engine. Failure to reverse all eight connectors will damage the coils, and possibly damage other electrical components in the car.

LFP provides a pair of billet spacers with each coil pack kit. The spacers fit between the "Powered by SVT"-embossed spark plug and cam covers. Axel installs form-fitting rubber gaskets inside each spacer, then secures them to the cam covers.

With the plug adjustments and coil replacements taken care of, Axel moves on to the stock upper pulley and uses LFP's Pulley Puller to remove it.

On the left is the LFP 2.80-inch upper pulley. The larger-diameter stocker (3.00) is on the right. Smaller pulleys increase the amount of boost that the supercharger generates. By installing this 2.80-incher, you can expect to see up to 4 extra pounds, depending on your Shelby's induction and the weather conditions. The 4 pounds could equate to a gain of about 70 rwhp once the SCT tune is applied.

This hub is the key to the LFP Quick-Change pulley kit for Shelby GT 500s.

Axel uses a bearing and the LFP Pulley Puller to press the hub into place, then bolts down the new pulley with the supplied Allen-head bolts.

Shelby GT 500s use an ECU called Silver Oak, which features a processor that is larger and faster than the Spanish Oak PCM we saw for the first time in '05 Mustang GTs. As one would expect, the new computer technology requires aftermarket tuning programs for manipulating its spark and fuel adjustment parameters. Timing and fuel settings are generally soft from the factory. Adding or removing spark in the critical areas of rpm ranges optimizes performance across the entire power band. SCT developed and offered tuning calibrations for Shelbys early in the game, and Andre Terranova, the tuning pro from Houston-based Custom Performance Tuning, has created a program specifically for LFP's new pulley upgrade.

SCT's XCalibrator 2 includes LiveUpdate software that allows users to download custom files into the programmer. Before we begin the dyno test, Saul "The Surgeon" Gutierrez of Extreme Automotive uses LiveUpdate to port a few additional SCT tunes into the XCalibrator 2.

The Xcalibrator 2 also serves as a datalogger, which we're using to display real-time PCM parameters and information right on our laptop computer. This benefit proves to be handy on Tom's GT 500 because it allows us to measure and verify the PCM changes while monitoring critical PCM parameters, such as temperature, mass airflow readings, spark, and fuel curves, along with up to 15 additional parameters. The LiveLink tool also allows us to map parameters over each other to view multiple functions simultaneously and see how each one affects the other, through the entire rpm range.

On the Dyno

ON THE DYNO
RPM Baseline Pulley & Tune Difference
TORQUE POWER BOOST RPM TORQUE POWER BOOST TORQUE POWER BOOST
2,028 258.61 104.97 5.62 2,009 403.28 163.44 7.23 144.67 58.47 1.61
2,130 263.34 112.30 5.81 2,114 408.85 174.29 7.46 145.51 61.99 1.65
2,210 268.45 118.78 5.90 2,224 417.56 187.33 7.72 149.11 68.55 1.82
2,319 278.84 129.44 6.06 2,328 425.18 199.67 7.98 146.34 70.23 1.92
2,430 291.14 141.60 6.35 2,413 429.66 209.08 8.23 138.52 67.48 1.88
2,536 298.57 151.55 6.57 2,525 434.14 221.11 8.48 135.57 69.57 1.91
2,609 303.19 158.32 6.70 2,615 436.17 230.02 8.63 132.98 71.71 1.93
2,700 308.68 166.84 6.89 2,703 437.99 238.78 8.73 129.31 71.94 1.84
2,800 313.11 175.52 7.12 2,816 442.09 251.10 8.89 128.98 75.59 1.77
2,909 318.12 185.26 7.29 2,906 445.49 261.14 9.02 127.37 75.89 1.73
3,011 323.47 194.98 7.40 3,019 450.87 274.57 9.22 127.41 79.59 1.82
3,115 329.32 205.37 7.53 3,125 455.88 287.32 9.36 126.56 81.95 1.83
3,223 334.59 215.89 7.63 3,204 459.47 296.89 9.50 124.88 81.00 1.87
3,319 339.45 225.51 7.70 3,324 463.33 310.64 9.59 123.88 85.13 1.89
3,418 344.80 235.91 7.74 3,408 465.42 319.90 9.64 120.62 83.99 1.90
3,518 349.23 245.92 7.82 3,522 467.03 331.74 9.72 117.80 85.82 1.90
3,623 352.83 255.89 7.92 3,603 467.88 340.02 9.77 115.05 84.13 1.85
3,716 355.96 264.75 8.01 3,711 469.96 351.78 9.82 114.00 87.03 1.81
3,822 358.21 274.03 8.06 3,823 471.20 363.36 9.96 112.99 89.33 1.90
3,923 359.78 282.55 8.11 3,913 472.17 372.68 10.07 112.39 90.13 1.96
4,014 360.97 290.06 8.20 4,004 473.23 382.15 10.07 112.26 92.09 1.87
4,115 362.15 298.30 8.23 4,112 474.53 393.61 9.99 112.38 95.31 1.76
4,218 362.60 306.15 8.24 4,222 475.26 404.76 9.96 112.66 98.61 1.72
4,318 362.73 313.50 8.27 4,322 475.36 414.35 9.88 112.64 100.85 1.61
4,429 363.45 322.21 8.26 4,412 475.20 422.84 9.84 111.75 100.63 1.58
4,525 364.16 329.81 8.24 4,501 474.24 430.54 9.74 110.08 100.73 1.50
4,634 364.42 338.05 8.22 4,611 471.67 438.67 9.67 107.25 100.62 1.45
4,714 365.10 344.48 8.21 4,702 469.84 445.54 9.64 104.74 101.06 1.43
4,804 366.09 352.02 8.19 4,804 466.68 452.17 9.59 100.59 100.15 1.40
4,902 367.31 360.40 8.13 4,920 464.34 460.72 9.58 97.03 100.32 1.45
5,007 368.29 369.13 8.03 5,004 462.02 466.30 9.48 93.73 97.17 1.45
5,101 367.75 375.48 8.03 5,115 458.80 473.25 9.52 91.06 97.77 1.49
5,203 367.12 382.32 8.06 5,201 456.96 479.33 9.56 89.84 97.01 1.50
5,329 365.64 390.02 8.02 5,316 453.21 485.89 9.59 87.57 95.87 1.57
5,431 363.34 395.01 7.95 5,427 448.93 491.31 9.58 85.59 96.30 1.63
5,504 361.62 398.38 7.93 5,510 445.83 495.44 9.55 84.22 97.06 1.62
5,606 358.98 402.84 7.95 5,618 441.38 500.12 9.50 82.40 97.28 1.55
5,710 356.05 406.93 7.98 5,703 437.03 502.68 9.50 80.98 95.75 1.52
5,814 353.81 411.78 7.98 5,815 431.36 505.95 9.54 77.55 94.17 1.56

We strapped Tom Pence's upgraded Shelby to the pods of Extreme Automotive's Dynapack Evolution 4000 chassis dyno and were immediately treated to impressive peak performance. Keep in mind, the Dynapack loads the car based on its weight, so these numbers are lower than what you might see on an inertia dyno, such as a Dynojet. Also, it doesn't output the numbers at an even rpm, so our traditional side-by-side comparison isn't as accurate, but you get the idea.

The Lightning Force Performance 2.80-inch pulley and high-output coils helped the Shelby put down peaks of 508 hp at 6,000 rpm and 475.4 lb-ft of torque at 4,351 rpm, a gain of nearly 70 hp and 107 lb-ft of torque over our baseline peaks. The boost gain was only 2.6 psi at peak on the car's boost gauge; the dyno's boost sensors read lower. We think it will rise to the 4 psi that the pulley is designed to produce with the addition of a cold-air induction system.

We're fairly sure that with the addition of cold-air, the smaller, 2.60-inch pulley and additional SCT tuning, the Shelby GT 500 will easily put down close to 100 additional rear-wheel horses. The trick is to find another owner like Tom, who is willing to let us go there with his car.