I'm trying to figure out this whole compression theory crap.... Simple favor to ask of you guys....... Please post your year, which intake manifold it came with, and if it's a USDM or JDM b20b...... LASTLY, if it has a 3 layer or 2 layer head gasket.... if you don't know how to tell, it's really easy, just look at the gap right here:


or here:


I'm trying to figure out what the standard is. Especially from you USDM B20b owners. Mine LOOKS like a 2 layer to me.... My friend tells me the standard should be a 3 layer.... so this is what I am checking now...... If the standard is a 3 layer, then perhaps, some JDM B20Bs do have 9.2 compression because of the thinner head gasket. All 96-98 B20bs prolly do have P3f (lower compression) pistons (versus the higher compression PHK pistons), but with a 2 layer gasket (if it's not the standard), it should yield a higher compression.....

So far from my research on a bunch of boards, the going theory is.......

96-98 JDM B20B = 8.8 Compression
97-98 USDM B20B = 8.8 Compression

99+ JDM B20B = 9.6 Compression
USDM B20Z = 9.6 Compression...

And if your still stuck in the past..... NO, not all JDM b20b's have 9.6 compression. That was alreayd been proven by many (pulling the head and looking at the pistons).

 

The actual difference in volume created by a third layer is negligable, and would not cause a difference of .8/1 compression. The difference in those engines is all in the pistons and the combustion chamber size (built in to the head).

 

uh, I didn't say the missing layer would cause a difference of .8 in compression...

From my research, there are THREE different compressions... 8.8, 9.2, and 9.6.......

My theory is..... the 8.8 compression b20bs are p3f pistons with the standard 3 layer OEM gasket (however, I am still waiting for someone to say they have a 3 layer gasket - 97-98 CRV owners?)... It could be the b20s had a 2 layer as the standard OEM (which is weird because almost all hondas have 3 layers)...

then the 9.2 compression is the p3f pistons with a 2 layer gasket.........

and lastly the 9.6 compression is the phk pistons and standard 3 layer gasket.......

A missing layer could cause a .4 difference I think... Especially if it's the middle layer of the OEM standard 3 layer right??

Again, this is just my theory.... No one else on any forum has ever attempted to explain the 9.2 compression other than saying mis print by Honda.jp which I highly doubt since it's listed like that 3 different times for 2 different cars...