I'm going to check them out now, thanks!

 

Yeah, those pistons don't help matters at all.

Assuming the pistons come .006" out of the hole, using a Cometic .040" thick, 3.910 bore gasket, you'd be at around 9.5:1 with 61cc chambers. If you shave the heads down to 58cc chambers, you'd be at 9.9:1.

If you are happy with that number, then bravo. Personally, I'd be switching to a flattop piston to get a compression ratio between 10.5-11:1.

 

He said he's still going turbo. No need for 11:1.

 

Sorry. I thought he was still going N/A with the 5.3.

 

Ok! 9.5 will work great, I'm going to start looking around for 243s. I really appreciate all of your input guys. Thanks

 

Trickflow makes 205 heads with 58cc chambers that are made for the 5.3.

https://www.summitracing.com/search/...3l-5-7l-vortec

 

Dart 205 LS heads, Edelbrock LS heads otherwise get 243. Not gonna matter much if your supercharging or turboing.

 

Ok guys, this is where I'm at. My internals were at my machine shop, I went to go check on them and I told him about the compression issue. He told me he's a wiseco dealer and that he can swap out my dished piston for a flat top with valve relief, which would put me at 9.3ish:1 compression. Im really happy he could do that, which means I can still run my 317s but I might bring it up to around 10:1 of I opt for some 243s.

He told me he just got done building a forged 5.3 with same setup and made 1000+ hp to the wheels, he had it set to 23psi but it boost spiked to over 30. Holy crap, and he's running 10.5:1 cr on 110 octane.