P29 pistons in an otherwise stock D16Z6 engine even with the stock Z6 metal headgasket doesn't net 14:1 CR, it only nets 12.0 CR.
Here's the compression calculator:
And here's the numbers you punch in:
Bore - 75
Stroke - 90mm
Combustion chamber volume - 34.6
Piston dome - +7.2
Head gasket thickness - .037
Piston-to-deck height - .040 <------------------- thats what throws everything off.
CR comes to 12.03 with a displacement of 1590cc
I bolded the piston-to-deck clearance because too many people use the wrong number here. You need to use the number for the *PISTON* going into the block, not the block itself.
Had I punched in the piston-to-deck number for the D16Z6 I would have gotten a way incorrect 13.6:1.
There have been many pump gas D16Z6 engines built with P29 slugs, so that alone should tell you that the 14:1 number is wrong.
The only thing to watch out for with the P29 pistons with a VTEC head are the valve reliefs. they do not latch up the same, but they do clear unless you go crazy with the mill or have some crazy-ass cam with a shitload more lift than stock.
I'd go with the least amount of mill on the head and not deck the block to ensure good piston-valve clearance.
If you need the D numbers here they are:
12:1 is 100% totally streetable on 93 octane fuel. Hell I've got a few friends running 12.5:1 on pump gas too. These are B VTEC builds making over 200whp on pump gas that ar also daily driven with zero problems.
So my point is that I think you should run at least the flat top 86-87 pistons or even better, the P29s fropm the 88-89 Integra.
I fell victim to the misleading info before someone correceted me. A very knowledgable person on honda-tech.