SLP's '95 six-speed test car proved exceptionally brawny in unmodifiedform, channeling 277
With 400- and 500-horsepower factory Corvette engines now a cold reality, it's easy to overlook the critical role the 300-horse LT1 once played in maintaining the car's status as a credible world-class performer. When the C4's accelerative supremacy was usurped by a renascent crop of turbocharged Japanese coupes in the early '90s, it wasthe lusty, free-revving LT1 that provided the quickening stimulus needed to propel the Vette back into the supercar vanguard. Tuners quickly set about mining more verve from this promising newcomer, and the LT1 soon achieved moderate celebrity as a powerful and reliable platform for high-performance engine buildups.
Fast forward to present day, and the availability ofapplication-specific power upgrades for the LT1 is distressingly limited. This decline can be traced directly to the ascension of the LS-series engine family, whose unprecedented responsiveness to all forms of performance tuning has made it the new darling of serious speed merchants throughout the United States and beyond. As the aftermarket scrambles to extract ever more implausible dyno numbers from these alloy uebermotors, dedicating valuable engineering and production resources to the development of new parts for the aging LT1 has become all but impossible to justify.
This aluminum "flow booster" mounts in the throttle body and purportedlyincreases intake-a
Fortunately for the owners of the roughly 100,000 '92-'96 Vettes still plying the macadam, a few prominent tuners have remained true to the LT1 cause. One such stalwart is Toms River, New Jersey-based SLP Performance Parts, whose packaged horsepower prescriptions for LS1- and LS2-poweredcars were covered in some detail in past issues of VETTE. With the introduction of its 330HP PerformancePac (PN 24000) for LT1 C4s, SLP can now boast of offering jointly engineered upgrade kits for virtually all Corvettes manufactured in the past 14 years. (The low-volume ZR-1 is anotable exception.)
Slightly less comprehensive than its later-model counterparts, SLP's LT1 package comprises a cold-air induction setup, a throttle-body-mounted "flow booster," a set of 1.6-ratio roller rocker arms, and a converter-back exhaust system. The idea, according to engineering chiefBrian Reese, was to extract LT4-quality horsepower numbers from the motor without incurring the expense or mechanical headaches associated with changing out the factory cylinder heads, intake manifold, or camshaft. The 330HP PerformancePac retails for $1,399.80, and all of thecomponents are also available separately should one prefer to tackle the buildup incrementally. (Popping for the whole package at once does, however, shear $75 from the final tab.)
Team VETTE was recently allowed inside the SLP engineering works to document the installation and dyno testing of the company's very first LT1 PerformancePac. The accompanying photos and captions detail the results of the operation, which suggest that--age and diminished popularity not withstanding--the final chapter in Chevy's small-block sagaremains the most compelling.
Unique among Corvette induction packages, the SLP unit uses a trio ofhigh-flow air filters
The cold-air package and flow booster added 8.3 hp and 9.8 lb-ft at thetires on the otherw
Equipped with 2.5-inch mandrel-bent tubing and a pair of free-flowingmufflers, SLP's C4 Po
The heavy hitter in the group is a set of 1.6-ratio extruded-aluminumroller rockers from C
No PerformancePac would be complete without a pair of fender badges.Despite their snazzy a
In total, the 330HP PerformancePac swelled the '95 Vette's rear-wheeltallies to an LS1-cha