Dale Amy
March 9, 2010

Horse Sense:
The higher the altitude, air temperature, or relative humidity, the lower a naturally aspirated engine's power output because of the diminished air density that results from each of these factors. Less density means less air for combustion on each power stroke. This makes the charge-air compression of a supercharger or turbo so much more important in high, hot locales.

Chris Crosby makes his home in Albuquerque, near the base of the Sandia Mountains at an elevation of around 5,000 feet. While New Mexico's high-desert surroundings offer a scenic vista, that altitude takes a bit of getting used to. Humans can eventually adapt to the thinner air; engines not so much, at least notwithout help.

At these heights, forced induction is to an engine what an oxygen bottle is to a mountain climber: a virtual necessity. Which helps explain why there's a big freakin' ProCharger D-1 under the hood of Crosby's '02 Laser Red GT-a coupe that Chris just about gave up on a year or so ago.

Rewinding to the beginning, Chris bought the GT in 2003. He was around 19 at the time, and the pre-owned Mustang was almost stock and had around 4,000 miles on the clock. With a K&N filter and an after-cat exhaust, it would run 14.6 seconds in the quarter-pretty good considering the elevation. Not good enough for Chris, of course. The nature of his job at the time-or at least its paycheck-was such that he could only afford small bolt-ons for a while, but he knew elevation was his GT's enemy. In 2004 he added a 75-shot NX nitrous kit and was happy with the power, but hewisely worried that without a corresponding tune, bad things might happen. So he pulled the plug on the nitrous and started saving for blower, which arrived in 2005 in the form of a ProCharger P-1SC.

In the meantime, he had lunched his stock TR-3650 tranny, so in went a D&D Performance T56. All was well until, as Chris explains, "With 90,000 miles on the car, the times of running nitrous through the blower killed the pistons." With short-block work required, he had to decide whether to "go big or go stock."

Obviously he went big, opting for a VT Engines 302-inch stroker, with VT's Stage 2 heads and cams, and a Fox Lake P-51 intake. (We're guessing the paycheck thing was getting much better by then.) While waiting for the engine, he upgraded to a 26-spline input shaft on the T56, and stepped up from ProCharger's P-1SC to a D-1SC, taking the GT to Dave Rochau at Motiva Performance Engineering to "finish the project and tune it."

By then it was late 2007, and with all his resulting enthusiasm, Chris managed to put the hurt on a shift fork and gear in the tranny, so off it went back to Michigan for a D&D rebuild. He also ordered an Aeromotive return-style fuel system and got the whole thing back together in March 2008.

At 12 psi, the combo put 653 hp and 589 lb-ft to the wheels, but as Chris says, "I was spinning the blower well over the max impeller speed, so it was forcing in a lot of hot air. The car just sounded mean with all the air blowing through a 50mm Turbosmart blow-off valve."

Then disaster struck: "The car had a 60-lb/hr injector lock up, filling the cylinder with fuel on No. 7, blowing out the spark plug and catching fire."

Subsequent repairs included heli-coiling the damaged plug threads and replacement of charred wiring, and all was good until late 2008 when, hot-lapping at the dragstrip, the same head cracked, feeding metal into cylinder No. 8, taking out both head and piston. At this point, Chris was "about done with this car."

But the bond of man and Mustang was too great, so back it went to Motiva once again, this time to have the block bored 0.020 inches for a new set of CP pistons, as well as a pair of Livernois Stage 2 CNC-ported heads. At the same time, Chris pullied down the boost: "The car now has intake temps down almost 80 to 100 degrees and is making 604 rwhp and 517 rwtq at only 9 pounds of boost. At this power level, the car is more reliable and a blast to drive. It is more than enough power to be driving on the streets."