Danny Dame Asks … What’s Needed to Swap an Earlier LS1 in Place of a 2005 Vette LS2?
Q: I have a 2005 Corvette six-speed with an LS2. Can I change it to an LS1 easily? Can you tell me how?
A: Certainly possible, but it’s a step backward. Like General Grant, I always want to move forward, never retreat. The first “Generation III” (Gen III) small-block, the 1997–2005 LS1, displaces 345.7 ci (3.898-inch bore x 3.622-inch stroke). Depending on the chassis and model year, stock output ranged anywhere from 305 to 350 hp. As installed in the 2005 Corvette, the 400hp, 364.1ci (4.00-inch bore x 3.62-inch stroke) LS2 marks the initial transition to the revised and improved “Generation IV” (Gen IV) small-block. Compression ratio was also higher on the LS2: 10.9:1 versus the LS1’s 10.25:1. You’d be giving up about 18 ci, at least 50 (if not more) hp, and 0.65 points of compression.
With its thin, centrifugally cast liners, an LS1 aluminum block has virtually zero rebuild potential. On 1997–1998 blocks, production process issues can result in the bore liners ending up not perpendicular to the block casting. One row of cylinders may end up thinner than specification. Those early blocks can be overbored just 0.004 inch. 1999-and-later LS1/LS6 blocks corrected the issues, but even they can go only 0.010 inch over max. By contrast, the LS2 Gen IV block’s 4.0-inch bore will go 0.030 over, yet the wall, post overbore, is still thicker than any LS1/LS6. Thanks to
