So I’ve acquired a lq9 longblock and I’m thinking of boring it. L92 heads, ported rod mod ls3 intake, forged pistons/forged rods, stock crank. Wanting high 11:1 to low 12:1 compression. I know it’s recommended to sonic test the block (which I will do), but I want y’all opinion on how much I can bore my lq9 out to. I was thinking 4.070, let me know what you guys think

 

I don’t suggest any more than 4.040 Beyond that all you’re going to do is make the cylinder walls really thin at the expense of next to no power gain.

 

Don't do it. Get a 6.2L block

Keep the walls as thick as possible for forged pistons.