Originally Posted by dstn2bdoa
Thanks Joe, I've allways understood that bigger is better with oil lines. What Im trying to figure out is the relationship between psi and flow. Aparently the drop in psi due to smaller lines,
When you flow a volume of fluid through a restriction, you get a pressure drop. If you flow the fluid through multiple restrictions in series, then you get several pressure drops, which are additive in nature. It works exactly like electricity flowing through series resistors. And as with electricity, you will measure a different pressure in the system depending upon where you take the measurement- ie: which restrictions are before the measurement, and which are after it.
The biggest restriction in the system is the bearings. After them, you have zero pressure, and before them, you have some pressure. We want to measure the oil pressure just before the bearings.
In the stock system, there is only one other major restriction- the oil filter. The pressure sensor is placed after this, so it reads the pressure at the bearings, or at least as close to that pressure as is practical.
If you add another restriction after the oil filter but before the pressure sensor (a cooler and lines) then of course the pressure loss across that restriction will show as a drop in pressure at the sensor. The key point is to make this path as non-restrictive as possible, by using large diameter lines, hose-ends that are gradually swept rather than a sharp turn, and a cooler that is of the parallel-plate design.
is becuase the sender is after the restrictions.
This is why you are able to see it, yes. If the sender were before the restrictions, then you would see a higher pressure, but this would not accurate reflect what was going on in the parts of the engine where it counts.