Close. You did pick up on the two separate circuits... Before the relief valve opens you're correct, the oil has to turn 90, then 180 then drop down and only feed one side of the pump gears on the low pressure side of the pump. After the pump makes enough head pressure to open the relief valve, then the other corner of the gear face gets oil flow (from the filter adapter).
With my hole, the oil enters the timing cover, jogs left and hits the gear face right in the middle of the gears. The original passage is still free to flow if there's low pressure in that port. Once the bypass opens up it will still send oil back to the suction side just like normal as well.
That's what sucks about the factory oil circuits in the pump. The intake is starved a little until it gets the pressure up to the bypass point. Imagine having a MAF pipe that's restricted until you get to 15#s of boost. It would spool like a dog and the bottom end would be soggy as hell while it gasps for air. That's why these cars have a reputation for crappy oil pressure at idle. Couple that with a factory oil filter (worse if there's a Fram there), and it's a low rpm POS pump.
I was inspired to drill that area by looking at pictures of the KB booster plate on Steve Woods site back when I wrote that oil pump article. I compared it to a thrust plate, noted the difference and realized I could replicate it with a simple hole. By giving the oil a path of lesser resistance, it will take it every time.
My car has neither one of those plates, no HV gears, the weak spring, 18mm filter, and 0W30. The light goes out before the engine starts.
With my hole, the oil enters the timing cover, jogs left and hits the gear face right in the middle of the gears. The original passage is still free to flow if there's low pressure in that port. Once the bypass opens up it will still send oil back to the suction side just like normal as well.
That's what sucks about the factory oil circuits in the pump. The intake is starved a little until it gets the pressure up to the bypass point. Imagine having a MAF pipe that's restricted until you get to 15#s of boost. It would spool like a dog and the bottom end would be soggy as hell while it gasps for air. That's why these cars have a reputation for crappy oil pressure at idle. Couple that with a factory oil filter (worse if there's a Fram there), and it's a low rpm POS pump.
I was inspired to drill that area by looking at pictures of the KB booster plate on Steve Woods site back when I wrote that oil pump article. I compared it to a thrust plate, noted the difference and realized I could replicate it with a simple hole. By giving the oil a path of lesser resistance, it will take it every time.
My car has neither one of those plates, no HV gears, the weak spring, 18mm filter, and 0W30. The light goes out before the engine starts.
