Quote:
Originally Posted by SBSerpent
Just wondering what are the parameters that cause the oil pressure to rise and fall....and what is considered 'normal' at idle and at higher revs. |
In broad terms:
The maximum pressure is somewhat controlled by the spring in the
oil pump. The valve opens when the max pressure is reached, and
oil is diverted back to the oil pan. A high pressure pump usually just has a stiffer or shimmed relief spring.
If bearing clearances are tight, pressures tend to be higher. Think of putting your thumb over the end of a garden hose. Bearing clearances tend to increase as the surrounding metal gets hot. When bearing clearances increase, pressure drops a bit.
Higher viscosity oil will increase pressure to a point. Going from 30-40 probably won't change anything. But going from a 30 to a 60 probably would.
The old adage is 15-20 psi at idle, and add 10psi for 1,000 rpm's doesn't really work all that well with modern technology. 15-20 at hot idle is good. But max pressure for most engines should be 45'ish.
It takes energy to create pressure. The more energy you use to spin the motor around, the less energy reaches the tires.
The drive mechanism is off the front of the cam, and through the distributer gear. Work that mechanism too hard and it will eventually break.
There is no need ever for a high pressure pump on a Ford Windsor engine. There's a lot of debate about high volume pumps, though.
You need enough oil viscosity to maintain proper pressure, and no more. If your street engine maintains good pressure with 0W-20 oil, there is no advantage to using 5w-40. Race engines can see improved valve train stability with a 40 oil.