getting a custom chip done for my 90 iroc

putting a new engine together but havent begun and dont be able to for a little while longer

is there any way to figure out the ratio but the parts (ie. heads, bore) ect?

 

You can calculate the compression ratio from the nominal specs of all the components. The exact value may vary from this by a small amount depending on the exact final configuration.

 

what info do i need and how do i calculate it ?

 

If you find an online calculator it'll tell you what you need to know.
Bore
Stroke
Depth of piston from deck of block at TDC (there are ways around actually measuring but of course room for error by not measuring)
CC of dish or dome on piston
Gasket cc (can figure from bore size and gasket thickness)
Combustion chamber cc

 

Download and install this calculator

http://cochise.uia.net/pkelley2/dcrvb6.zip

Does static compression ratio calc and if you have cam specs does DCR as well .Just put info in the boxes

 

what is DCR?

 

Dynamic compression ratio. Most people when they talk about compression ratio, they're referring to static.

 

how can i figure out the valve relief (in positive cc) ? im unable to get ahold of the shop i bought the engine from right now,is there a general kinda number? they dont look to radical theyre flat tops just have the valve reliefs .

 

Have you got a part number for the piston?

 

2 valve relief pistons (one intake and one exhaust) are in the 6 cc range.

Jake