6.4 Compression ratio question

[24vbummins]

I have most of what I need to build a 6.4 out of spare parts. I know the most correct way is to run longer connecting rods, followed by decking the block .070 to make up the difference using stock length rods to keep the compression ratio the same. My question is, without decking the block, what would the compression ratio be using stock length rods.
I remember someone had posted it before but I can’t find it.
I want to see 1000-1200hp and figure the easiest way (both with what I have and on parts) is 12 valve rods and lowering the compression. I could also run a larger cam without flycutting the piston. The truck is just a toy so hard starting doesn’t matter.

[Smokem]

13.85:1

[24vbummins]

Thanks Weston. Sorry if this is a novice question, but what effect would that have on timing to avoid spraying out of the bowl?

[Smokem]

Contact area of the spray pattern would be altered by ~ 4-6° which isn't that big of an issue, but that compression is quite low for your power goal and a single pressure stage.

[24vbummins]

I remember reading optimum compression ratio for a diesel was 14.9:1. This was years ago though. Would taking .030-.040 off the block bring it up closer to that? Although I was trying to avoid modifying the block to eventually go with a longer rod. I could always find another block later on.

[TBittner]

I thought for the 6.4 long rod a 5.9 crank was to be ran? It was my understanding that combo left the block unaltered.

[24vbummins]

Yes, that’s the plan. 6.7 block, 5.9 crank and rods. The longer rods aren’t currently in the budget.

[Smokem]

Originally Posted by 24vbummins

I remember reading optimum compression ratio for a diesel was 14.9:1. This was years ago though. Would taking .030-.040 off the block bring it up closer to that?

Removing 0.030" from the deck would be 14.95:1