can someone explain what overbore is and how it is done? Is it when they bore out your engine cylinders to make them bigger? I plan on rebuilding a 3.8 engine and heard that you can up the hp by changing the compression ratio and the overbore. Any help would be great, thanks.

 

Overbore is making the cylinders bigger. It increases displacement slightly, and you'll need new pistons. The most to safely overbore a block is usually .060 over.

 

Dont overbore it, just get a 4.2l crank.