Choice of two CR's...
 

I have the choice of running 10.3:1 or 11:1 in my new 408 block depending on whether I get the diamond flat tops with 2cc reliefs or the Wiseco's with the 8cc reliefs. I will be running my stock LQ9 heads and my 244/248 112 +4 cam. I also plan on doing a heads upgrade in the next year or two, as well as *possibly* a 100-150 shot of the giggly gas. Which compression would I be better off with in the long run? The diamond's would give me better numbers right now but might give me a bit too much compression with a future head upgrade. I'm having a hard time deciding and I want to order this block by the end of the week.

scr of 11:1 is fine with that combination, imo diamond makes a better piston

I agree that 11-1 is fine but i would choose Wiseco over Diamond

I would do the 11.1 and wisecos also

run a nice quench with .040 or .043 gaskets and run 11.3:1

The anti knock benefits of a proper quench will make up for the bump in compression's tendancy to knock on pump 93

From what I've heard, Wisecos are preferred for the most part over the Diamonds. Erik at HPE actually said they usually have to grind the skirts of the Diamonds a bit to keep them from hitting the Callies crank, but that doesn't make them of any lesser quality than the Wiseco's, just have to do a bit more work for them to fit. I am actually leaning more towards the Diamonds though to run a bit more compression. According to Erik, the quench with those is actuall going to be damn near perfect (~.040-.041) with a stock 6.0 GM MLS gasket and the Diamond pistons, as the pistons are built around .008-.010 out of the hole.

You can get a flat top wiseco pistons with 2cc valve relief from an of the shelf piston. Or for a little more money you can have custom pistons made which is what i did. Flat top wiseco's w/ 2cc valve reliefs and lateral gas ports :chug:

How much did those run you? And from who?

LME is building my 408 and the custom Wiseco's cost me an extra 350.00 so i'm not sure what there exact cost is if you buy them outright. With my AFR 225's and a felpro gasket .041 i think my comp should be around 11.25cr

Stock mls are .060 How do you get .040 quench with .010 out of the hole?

Assuming 72cc chambers, you'll run 10.9 with gm mls and 11.4 with .040 cometics. I am running .043 SCE titan ICS gaskets for a sweet 11.3 and a nice quench of .033

I'm just going with the info that Erik is telling me with his calculations that he's done. Any downsides to your running 11.3 compression? Is it a daily driver?

Quench is key on larger bore engines. I've run 12.0 on pump gas (94) with a 4.100 in bore before. I haven't installed this setup yet but I am not worried at all.