CLICK HERE FOR THE DYNO SHEET ON ALL THE PARTS USED IN THIS INSTALL
The K&N AirCharger is bench...
The K&N AirCharger is bench assembled first. Saul transfers the GT 500'sOEM mass air sensor using hardware supplied in the kit. Fittings andgrommets for the factory crankcase vent hose and vacuum vent line arealso installed at this time. A rubber weatherstrip is placed around theheat shield to ensure good contact with the 'Stang's hood when it'sclosed. It also creates a pocket that prevents underhood hot air fromleaking into the cold-air-inlet area.
K&N AirCharger
We've been itching to give K&N's Shelby GT 500 cold-air system a try fora long time. We learned about the AirCharger and itspower-increasing-potential for GT 500s in January 2007 after meetingwith representatives from the company to discuss products and projectopportunities.
For the Shelby 'Stangs, K&N eliminates the super-restrictive, factoryair inlet and airbox assembly and employs a large, conical, high-flowair filter and straight-shot inlet tube. The tube fits cleanly into theengine compartment using the included factory silicone couplers and asingle anchoring bracket.
The AirCharger definitely adds insane rear-wheel power, even with thenew exhaust's gains taken out of the equation. We inspected the sparkplugs after our final dyno run and discovered that the horses come at apotentially huge expense. Ashen-white spark plugs tell us the systemwill be better served by a custom tune. With that, we move on to thefinal stage of our testing.
 The most challenging part...  The most challenging part of this installation is resecuring the largerbolt for the alternator housing, which must be removed for installationof the new inlet tube's support bracket. It's a tight squeeze for bighands, but doable nonetheless. |  |  As we suspected, K&N's AirCharger...  As we suspected, K&N's AirCharger makes a great deal of bolt-onhorsepower. It's important to note that with our 91-octane fuel and lackof catalytic converters, we saw that the engine's air/fuel mixturebecame alarmingly lean at wide open throttle, with the spark plugsgapped at their stock 0.040 setting. This problem is easily corrected byusing colder plugs or gapping the stockers down to 0.030 or so, andmaking timing and fuel adjustments using SCT's XCalibrator 2 flash tunerand the dyno's wideband. |
After loosening the serpentine...
After loosening the serpentine belt, this Paul's High Performance 90mmidler wheel is bolted to the stock belt-tensioner arm with the noncoatedside facing the engine block. Paul's provides a new bolt with eachtensioner pulley, as the factory pulley's bolt can't be used. The newtensioner is required for the 2.6-inch blower pulley to ensure belttightness isn't compromised by taking up the small amount of slackcaused by the smaller piece on the blower.
PHP Pulley and Tune
While its 5.4 bullet speaks volumes about the uniqueness of a Shelby GT500, the Eaton Roots-style supercharger that sits atop the engine isdefinitely its piece de resistance.
In stock trim, we've seen as many as 8 psi of boost pump through a GT500's powerplant and make its bone-stock horsepower a respectable 440 to448 at the tires. That's not quite the hard 500 horses that themisinformed believe are hitting the ground.
Our test Shelby fell within the proven stock parameters, but as ourfinal tests confirm, there's always room for improvement.
To close out our research, we called Paul Svinicki of Paul's HighPerformance and ordered his company's 2.6-inch blower pulley and 90mmtensioner package, as increasing boost by speeding up the superchargeris the best plan of action with stock Shelbys.
Removing the stock pulley...
Removing the stock pulley on a Shelby GT 500's Eaton supercharger takessome doing. The pulley is pressed on with the attitude that it won'tever be removed, so be prepared to crank on the pulley extracting toolfor a while before it finally breaks free with a loud pop.
At this juncture, remapping the PCM is a must, due to the radicalchanges the smaller pulley makes on the engine's air/fuel mixture andthe other modifications we've made.
Custom-tuning on the dyno is the best way to get the most out of anyperformance enhancement for EFI 'Stangs. Paul is top-notch when it comesto using SCT's tuning software to dial in a modular engine.
Because we know you're asking, no, Paul didn't come to California toassist us. The tune for our test ride was set up at PHP in Michigan on asimilarly configured Shelby. It was loaded into SCT's XCalibrator 2handheld flash tuner. Once the plugs were installed and gapped down to0.028-inch and PHP's 160-degree thermostat was in place, Saul loaded thePHP calibration into the Shelby's PCM. It was time to hit the dyno for afinal look at the overall effect these simple performance upgrades haveon Kevin's once-stock Shelby.
To give you an idea of how things worked with the cross-country tuning,Paul's tune was almost spot-on for air/fuel (his test Shelby still hadcats in place), and the rev window for the blown 'Stang increased andnetted 10 psi of boost, thanks to the PCM update. All we added wasapproximately 4 percent more fuel to the tune and finished up withreally impressive overall results.
 Our new Paul's High Performance...  Our new Paul's High Performance eight-rib, 2.6-inch supercharger pulleyinstalls in straightforward fashion on its supplied mounting pedestal,which must be placed between the snout of the supercharger and thepulley itself. Saul uses a dab of blue Loctite thread sealer to fastenthe small Allen-head bolts that secure the pulley. |  PHP includes a 160-degree...  PHP includes a 160-degree thermostat with its Pulley Pack system. The5.4 modular in Shelby 'Stangs is a big-time heat container, and Paulbelieves this type of coolant regulation is a must for Shelbys driven ona regular basis, as boost levels and heat are increased by a pulleyupgrade and excessive heat can cause catastrophic damage to the engine.The thermostat swap is the final parts change in this project, and itonly takes seconds if you have a buddy handy to pop the new piece inplace immediately after the original is pulled out of its housing. |  Paul Svinicki uses SCT's Advantage...  Paul Svinicki uses SCT's Advantage III tuning software to set up customcalibrations for all variations of Shelby upgrades. He loads each tuneinto an SCT XCalibrator 2 handheld flash tuner that's shipped along withthe new pulleys and thermostat. PHP's calibration ID is written on theback of each XCal (in our case, "NVBS-KJ"), along with the date the tunewas created. |