The short answer is "yes". How low is low? And is compression low, and equal between adjacent cylinders? If you squeeze the radiator hose while trying to start the engine, can you feel pulsations? If the answer is yes to either question, you may have a bad head gasket.
no it will not unless the engine was extremely over heated destroying the compression
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
yes
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.
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.
The total volume of all the cylinders would be the cubic inch (cid) or cubic centimeter (cc) displacement of that particular engine.
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.