Now that I am getting my DAQ setup on the STI, I’ll have some more data to look at. Here is a graph of oil and fuel pressure by rpm. Oil pressure is pretty constant up to the redline of 7800, with just a bit of dip from 7200rpm up. I would normally want slightly higher pressure, but I’ll take constant pressure over dropping pressure at higher RPM. This is 15w40 oil, and the oil temp was about 210F. Oil pump is a factory 11mm STI unit, and engine rod bearing clearances around .0019 to .0025. This motor is one I built in the garage back in early 2013. The dip in oil pressure at 5700 rpm corresponds directly with a significant change in intake and exhaust AVCS, which are oil pressure controlled. Interesting. Oh and this is oil pressure measured at the back side port of the block.

The yellow line is differential fuel pressure, with an idle value of about 43.9psi. Ideally you would want that line to be perfectly flat, but as Lance Lucas said, ‘if we only had an infinitely long spring!”. It drops about 2.8psi over the entire pull, and this is with about 69% peak duty cycle. The pump is a single Walbro 450lph E85 pump in a Radium surge tank. (Direct wired power) I suspect it will fall quite a bit more at higher duty cycles, so I’ll probably jump to a bigger twin pump setup.

Both of these graphs look good, which is probably related to why the car is still running after 3+ years of automotive debauchery with the old EFR7670.