That's just a bare block. Compression and cylinder pressure are controlled by the heads, cam, and the recipricating assembly. You can build just about any compression ratio you want.
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yeah but without boring it, like i just put piston in without making a bigger hole or anything
That's still too vague. You'd have a bore with a piston in it. The piston has valve reliefs and you need to know their volume. You need to know how far from the top of the deck the piston reachs when it's at top dead center, and figure out the volume of that area. You need to know the volume of the dish or negative volume of the dome of the piston, unless it's a flat top. You need to know the volume of the combustion chamber of whatever heads you're going to be bolting onto the block. You need to know the compressed thickness of the head gasket you plan to use. (generally, .045" is normal, if I recall) You need to know the displacement of the cylinder, which is bore x 3.14 x stroke.
The result of all these measurements will give you the static (mechanical) compression ratio. Then the camshaft profile and lifter design (hydraulic, solid, roller) will have an effect on the actual running cylinder pressure (also known as dynamic cylinder pressure) at various RPMs. (of course, then volumetric efficiency of the engine will effect cylinder pressure, at various RPMs, too.)
The result of all these measurements will give you the static (mechanical) compression ratio. Then the camshaft profile and lifter design (hydraulic, solid, roller) will have an effect on the actual running cylinder pressure (also known as dynamic cylinder pressure) at various RPMs. (of course, then volumetric efficiency of the engine will effect cylinder pressure, at various RPMs, too.)
The bore has almost no bearing on the compression. It's piston/stroke/head combo.yeah but without boring it, like i just put piston in without making a bigger hole or anything
Do a google search on compression ratio. You'll find some good articles with pictures and diagrams to explain it.
so by boreing the block as nothing to really do with the compression ratio its just the piston cams ahead crank like your saying sry to repeat you guys but im just trying to get the facts right
If you bore the block, OR increase the stroke, you increase the volume of air being squeezed into the same combustion chamber size, therefore, you increase compression ratio.
Not much. The block just sits there. It's the combination of all the parts you put in it that determine the compression.so by boreing the block as nothing to really do with the compression ratio its just the piston cams ahead crank like your saying sry to repeat you guys but im just trying to get the facts right
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