The volume of an engine is called displacement and is typically measured in cubic inches or liters. An eight cylinder engine that could hold 1/2 liter of water (or air) in each cylinder would be a four liter engine. As the pistons move to the top of the cylinder in an exhaust stroke, they theoretically "displace" the 1/2 liter of air in each of the cylinders.
The compression ratio is calculated during the compression stroke. If the piston occupies 90% of the enclosed cylinder space when it is at top dead center, the compression ratio is said to be 10 to 1, or 10:1. If the displacement of the cylinder was 10 cubic inches, it would have been compressed to 1 cubic inch.
engine
The total volume of all the cylinders would be the cubic inch (cid) or cubic centimeter (cc) displacement of that particular engine.
It depends on equal compression between all cylinders.
worn or broken compression rings engine needs a rebuild
You may have compression on any cylinder where the valves happen to be closed, but you will not have compression on all cylinders. 1991 Sable does not have a 305 engine.
Cylinders compression pressure Sentra 1.8 : 192 psi
The repair depends on what is causing the low compression. Low compression can be caused by a blown head gasket, cracked cylinder head, burnt or damaged valves, worn or cracked piston rings, scored block cylinders. It's kind of hard to imagine that an engine would have low compression on all 6 cylinders unless something major is wrong, or the compression gauge is not measuring properly.
Most engine cylinders have low compression problem because the piston rings or valves have been warned out. Fixing these problems called engine overhaul and you need to have mechanical skills to fix it. It is impossible to explain how to overhaul an engine in a couple of sentences.
If there is NO compression on any of the cylinders, you've probably slipped the timing belt/chain. Just knowing that there is no compression is insufficient information to make a decision about replacing the engine. You COULD need to have the engine rebuilt, or it's possible that a valve "kissed" a piston and the engine is toast. Or... it could be something else. If it's just low compression in one or two cylinders, it could even be caused by burned or sticking valves.
It will vary from engine to engine but what you want to look for is that all the cylinders are within 10% of each other.
It varies with each engine but what is more important is that all the cylinders are within 10% to 15% of each other.
All the cylinders should be within 10% from the lowest reading to the highest reading for a healthy engine.