LT1 Engine Build - Pull! Part 1

When Chevrolet introduced the 300-horse LT1 (gen II) fuel-injected small-block in the '92 Corvette, it was a more advanced Chevrolet V-8. The LT1 was a high-tech 350ci 5.7L small-block Chevy that was a cut above the Tuned Port Injected 5.0L small-block first introduced in '85. The TPI set a new benchmark for performance when it debuted in the IROC-Z Camaro. It offered outstanding performance coupled with something previously unheard of with high-performance V-8 engines: fuel economy. Port fuel injection coupled with roller-tappet technology made the TPI a quantum leap in performance.

The LT1 took the TPI approach one step further, with features that made it a vastly improved small-block. The objective was cleaner emissions and greater sums of power. GM did away with the Chevy's rear HEI distributor and belt-driven water pump. Instead, it had a camshaft-driven, reverse-flow water pump, and something new in electronic engine control: Opti-spark, a pancake-style, light-triggered electronic distributor positioned beneath the cam-driven water pump. Reverse-flow cooling was adopted to compensate for the higher 10.5:1 compression ratio and leaner fuel mixtures.

What would be Chevrolet's selling point in technology would also be the LT1's undoing to some degree. Optispark was plagued with reliability problems, which sidelined a lot of Corvettes, Camaros, Firebirds, and Impala SS models throughout the '90s. Oil leaks around the water pump drive not only spotted driveways, but also Chevrolet's great reputation for reliability and performance. Between GM's efforts (and the aftermarket's) these problems aren't what they used to be. However, they have become something to be mindful of during your build-up.

Despite the LT1's engineering shortcomings, it was a terrific factory small-block sporting a nodular iron crank, powdered metal connecting rods, and hypereutectic pistons. In '92, the LT1 yielded 300 hp. By the end of production in '97, it was making 330 factory ponies in the LT4. GM made two types of LT1 blocks, two-bolt main and four-bolt main. Four-bolt-main versions were factory-installed in Corvettes primarily. But, be ready for a four-bolt-main block in just about anything. Because they both have the same casting number, they are impossible to identify without first removing the oil pan. Although most LT1 engines had aluminum heads, you need to be mindful there are LT1s with iron heads too (found in full-sized GM sedans of the era). Caprices had similar-looking small-blocks that weren't LT1s at all, but rather 265ci 4.3L engines. These guys are easily identified by their smaller 3.740-inch bores.

When we first decided to build an LT1, we understood it was a significant turning point in the small-block Chevy's 37-year history. It would also be the small-block Chevrolet's curtain call--the tail of a very successful design run that would end at the 42-year mark. Incredible success by anyone's standards. We decided to build a solid, reliable LT1 383ci stroker small-block to see how much power we could make from GM's 5.7L small-block. Mark Jeffrey of Trans Am Racing in Gardena, California, volunteered to build our LT1, with the objective being 450 hp over a broad torque curve. Mark had Air Flow Research cylinder heads in mind for our LT1 build, along with an aggressive street cam package that would be good for the commute and the racetrack. However, we were thinking more along the lines of something stealthy--stock in appearance on the surface, using genuine GM parts as much as we could on this project. We contacted Summit Racing Equipment to see what it suggested. We also called Coast High Performance, MSD Ignition, and COMP Cams. Here's what happened.