C/R (Compression Ratio) for the LS/VTEC
(B16a head on B18a/b block w/stock b18b rods) motor:


9.6:1 - P74 LS Pistons
10.0:1 - P72 GSR Pistons
10.8:1 - P73 US ITR Pistons
11.0:1 - P73 JDM ITR Pistons
11.5:1 - PR3 Pistons (1st Gen B16a)
11.7:1 - P30 Pistons (2nd Gen B16a)
12.4:1 - CTR Pistons

&

This is with the LS block with LS rods and a GSR (B18C1) head:

9.8:1 - P74 LS Pistons
10.2:1 - P72 GSR Pistons
11.0:1 - P73 US ITR Pistons
11.2:1 - P73 JDM ITR Pistons
11.7:1 - PR3 Pistons (1st Gen B16a)
11.9:1 - P30 Pistons (2nd Gen B16a)
12.6:1 - CTR Pistons

11.5:1 C/R is the "Safe" or target on 92+ oct street
pump gas.