Anyone have a ten cent explanation on what happens with low pressure or why or what oil pressure does in an engine?
Oil pressure helps forms a protective layer between vulnerable bearing surfaces and quickly spinning parts, preventing metal on metal wear. Your crank and rod bearings need that layer of oil to prevent major engine damage and valvetrain parts need a healthy flow of oil to keep things moving without excessive wear. There are oil passages in the engine that are fed from the oil pump at the bottom of the oil pan. Oil flows thru these passages to where it's needed, onto the camshaft bearing journals, the lifters and eventually feeding oil up the push rods and to the rocker arms, then it drains back down to the oil pan.
The general guideline is that an engine should have 10 PSI oil pressure per every 1,000 RPM. You can often gauge the health of an engine and the quality of the bearing surfaces based on the oil pressure, especially when the engine is hot and has been working hard. The more oil pressure, the less chance of bearing surfaces contacting the crank and really causing trouble, tearing up the engine.
Years ago I built a nasty SBC that had a high volume, standard pressure oil pump... lots of new parts, fresh machine work, tight bearing surfaces, etc. When it was just fired up and cold, it had a impressive 65 PSI oil pressure and once warm, 45 PSI. It had more than enough oil pressure to keep the internals happy.
You can get high pressure, high volume oil pumps, but they're typically for racing applications and you need to make sure you have enough oil (bigger pan) that you don't suck the pan dry and really eff up the engine.