I'm having a forum chat about an L31 crate engine as might be received from a place like Scoggin-Dickey. While we're waiting on an answer from them I'll ask here if anyone has definitively determined what the compression ratio is. I've heard anywhere from 9.3 (as listed on their website) to 10.3:1.
Thanks in advance.

 

I looked in the cylinders of mine with a good borescope, looks like the pistons are the 12cc dished, and 64 CC head chambers, and common GM head gasket and deck height puts mine right on the advertised 9.4:1

 

Generally, it's never been my experience that real, measured, actual compression is MORE than advertised. It is often the case that it is less.

With 9.3:1 advertised, I cannot imagine a 10.3:1 actual.

10.3:1 with iron heads going into a 1 ton work truck running 87 octane sounds like a recipe for disaster to me.

 

Doesnt it depend on its dynamic cr for what fuel it needs?

 

Recent GM corporate V8's based on the SBC architecture generally come with one of two heads, and almost always used the same pistons.

When it comes to engines that came in thirdgen's, or even later vortecs with iron heads, they are 64cc chambers and come out to 9.3:1 or so. GM really didn't change the recipe at all when it comes to the static compression.

 

9.3:1 seems a likely go to figure given what's been said here and my own research.
A forum member is looking to get one of these L31 Vortec 350's and the discussion has been around cam choices. It's looking like this is going to be around the short end of the scale with the relatively low CR.