Adding piston dish depth to CC?

[Töuge-MR]

I'm revisiting the ol' Compression Ratio calculations, and I'm confused as to how I would work out the extra CC that the valve reliefs, and dish depth would add to it.

I've got the following from the spec sheet for the 86.5mm pistons... 2.0L 3SGTE turbo

Dish Depth: -0.08
Intake Valve Relief: -0.22
Exhaust Valve Relief: -.180

How would I make these figures into a CC value?

I'm assuming a few values from other MR2 turbo owners ive seen around. Mainly that the combustion chamber has a CC of 49. Can someone confirm?

Thanks in advance for any help offered.

[powers]

you have to have the piston measured. Or you can estimate. If you do not know the base cc dish you began with you will need to measure it to be accurate.

At your HP level it will not be that crucial anyway.

[Töuge-MR]

At my HP level i dont even need to crack open the head, but im planning a lot more than what i let on i suppose. Do you think my factory base CC dish can be found in the OEM repair manual?

[maverickgrabber72]

the beck hight and head gasket plays into it also ....but if you have the head off you can check it with water or a thin oil

[Töuge-MR]

Yeah i was told to get a burette and use oil and try to avoid using water... is this acurate?

[powers]

You will be able to find the factory compression
You can use the other measurements to caluclate the dish if you need the specific number. If you are trying to find compression ration that should be an easily found item.

You will need to know the bore, stroke, deck height, head volume, and compressed gasket thickness. Those numbers plus already know what they total for compression ration will allow you to calculate piston dish.

The light oil techique works but is difficult if you have never done it.

[J-Spec Supra T]

You can use glass to press it up against, but try to use a thin oil.. water can get obnioxous lol