I'm trying to figure the compression ratio for a d16z6 head on a d16a6 block with oem size pistons, head gasket, and what else have you. I'm pretty sure that the piston dome number and the head gasket thickness is wrong but I couldn't find it for sure anywhere else. I just used the most common one I saw.

Bore – 75mm
Stroke – 90mm
Head gasket bore – 75.5mm
Head gasket thickness – 0.025mm
Combustion chamber volume – 34.6cc
Piston dome volume – 4.3mm
Piston deck clearance – 0.020mm

Compression Ratio – 14:1

Bore – 75mm
Stroke – 90mm
Head gasket bore – 75.5mm
Head gasket thickness – 0.025mm
Combustion chamber volume – 34.6cc
Piston dome volume – 0mm
Piston deck clearance – 0.020mm

Compression Ratio – 12.4:1


I know I did the math right, but I don't know if I used the right numbers to do the math. 14:1 seems a little high... Even with no dome it still souds to high at 12.4:1 compression. Anyone know (or know where to find) these real oem numbers?

 

using your numbers (i assumed you meant piston to deck clearance=0.020in. and not 0.020mm and that you meant 4.33cc dome volume and not 4.3mm), i get 12.23:1 with the 4.3cc dome and with zero dome/dish i get 11.01:1 - what pistons are you wanting to use?

 

Yes, you were right about what you were guessing. I'm probably going to be using the oem (style anyways) d16a6 pistons, pm6 pistons. If I'm not mistaken they're a -3.4cc dish. I'm not going to turbo it though, so I want to go higher compression. no more than 11.5:1 though.