LS7 Chevy Camaro and LSX Pontiac Trans Am

In GM Performance Parts' Latest endeavor to test out its products and show the world the wonders of LS power, it chose two in-house 4L60E-equipped F-bodies as the recipients of its latest and greatest crate motors. Sure the LS7-powered Goat and Camaro of last year ran like a brown bunny on crystal meth, but what happens when you bolt up one of GM's most popular four-speed automatics to an LS7 or a hopped-up 454-cube LSX motor?

That's exactly what GMPP hoped to find out when two former development cars, a GMMG 427 SS and a Collector Edition Trans Am convertible, were procured to test out several new prototype pieces soon to grace the pages of its catalog.

The Hugger Orange 2002 SS was originally a test vehicle, converted to GMMG ZL1 specs to develop a 4L60E-based trans capable of handling over 600 hp. As the result, it came to GMPP with a carbon-fiber high-flow air lid, chambered exhaust, and many unique aesthetic touches, such as the ZL1 stripes that adorn the fenders. The suspension and brakes, though, appear to be untouched. While the stock trans may have held up to 325 hp in stock SS trim, it had little chance of withstanding an LS7's punishment. The folks at GM Powertrain removed its guts and stuffed the casing full of heavy-duty 4L70E components, as well as a Corvette accumulator, and matched the trans to a '06 GTO converter. Just what, pray tell, is a 4L70E and what car does it come in? I guess we will have to wait and see ...

Now that the trans could contain it, the chassis was prepared for the addition of the dry-sump motor. The battery was relocated to the trunk, and the oil tank mounted in its place. A 3.73 ring-and-pinion replaced the factory 3.23 ratio for improved performance and to simulate a typical customer modification. Meanwhile, the factory LS1 computer was swapped for an E67 computer and harness that GMPP is producing to complement its Gen IV crate-engine line, which is compatible with the 58x reluctor wheel, relocated knock sensors, and electronic throttle. The SS was not unlike most any other application, in that using this setup meant rigging an electronic gas pedal and constructing a custom gauge cluster (since the E67 is not compatible with the factory electronics). GMPP's catalog of gauges came in handy for fabricating the new cluster, which added a custom look to the otherwise unmolested interior.

Aside from running custom oil lines from the oil tank to the dry-sump oil pan, no extra effort was required in bolting up the LS7 to the factory K-member and stuffing it back into the engine bay, as well as affixing all the accessories. The stock 427-cube crate engine came with ignition coils, intake manifold, fuel rails, injectors, and even exhaust manifolds. However, for a slight bump in the previously rated 505 horses, Stainless Works long-tube headers and Y-pipe were mated to the GMMG exhaust. With a custom calibration to the PCM, the LS7 runs flawlessly like an OEM motor-just with a little more bite.

In addition to helping put together the SS, Thomson Automotive played a big role in building the more highly modified Collector Edition Trans Am. Though the TA is believed to be a 2000 model that began its life at GM as sort of a prototype for the Collector Edition-it was born again with fresh paint and graphics to modernize the CETA look. At Thomson, 18-inch C5 Corvette wheels replaced the black WS6 rolling stock in order to fit a set of Brembo Gran Turismo four-piston front brakes with 13-inch cross-drilled rotors. The WS6 suspension was enhanced by BMR Fabrication's subframe connectors, torque arm, and transmission crossmember.

Editor Jensen got the chance to drive both of these beasts. "You gotta love the GMPP crew-crazy power and torque and radial street tires! My time behind both wheels alternated between sliding around as the big LS engines shredded the rubber and giggling like a schoolgirl as the revs climbed. But these two rides couldn't feel more different: The LS7 is the perfect mix of big-inch torque and ridiculous revs, and took some rpm before the tire smoke showed. The LSX was all torque, all the time: I swear at idle I could feel each massive slug pounding the foot-pounds out, and boiling the hides took only the smallest bit of throttle."

As indicated by the flat black panel just above the bumper and ZL1 stripes on the front end, this car was originally a GMMG 427 package that GM had converted in 2003 for transmission engineering and testing purposes. The tranny-developed to handle the original 600hp motor-has yet to see the light of day, but that may change soon with the many high-powered factory and GMPP crate engines hitting the market. This development vehicle had remained at GM's proving grounds until its LS7 conversion, and is credited for being partly responsible for the creation of the 2010 Camaro by its engineers.

The stock LS7 bolted right up to the motor mounts and accessories. However, to make room for the oil tank, the battery had to be relocated to the trunk. The 505-horse factory rating is maximized by the carbon-fiber air lid, Stainless Works headers, off-road Y-pipe and GMMG chambered exhaust.