Observed Oil Pressure with a gauge

MotorvateDIY

On the VHR, the oil pressure relieve valve is used to limit the maximum engine oil pressure to about ~95 psi (depending on oil temp) This is used to reduce oil pressure on cold starts and at RPM greater than about 4,000.

When at operating temperature and below about 4,000 RPM, the bypass valve is closed, so shimming it up has no impact to oil pressure.
Shimming up the spring does increases the maximum oil pressure, which I don't think is a good idea.

Here is some data from my G37 6MT with 130,000 miles recorded in August:
• Up to about 4,000 RPM the engine oil pressure increases as engine RPM increases in a somewhat linear / straight line, due to the bypass valve staying closed.

• From about 5,000 to 7,500 RPM the engine oil pressure is held somewhat flat/level. This is due the valve being pushed open by the oil pressure and bleeding off oil pressure as the engine RPM rises.



About the data source:
I've developed a module that plugs into the OBD port, reads the CAN bus messages and saves it in human readable format to a CSV file on the SD card 20 times per second.

Engine oil pressure and diff oil temp, are not on the CAN bus. They are received via Bluetooth using an under hood mounted module that powers any standard oil pressure sensor, reads the analog output, converts it to a pressure value and sends it out to the OBD mounted module using Bluetooth. From there it is saved to the SD card.

Attached Images

EOP_bypass.jpg (209.7 KB, 73 views)