Sorry for the delayed reply. It's been so busy building engines and tuning here I haven't had much time to test or share what we've tested on our FRS.
So what you are looking at are the two oil pumps from the FRS/BRZ and the 2015 WRX timing cover and oil pump.
There are some significant differences and improvements (we feel) with the 2015 WRX's 14mm oil pump. The first thing you'll notice is how much thicker the pump gear is (12mm vs. 14mm). The other item is the oil pump gear tooth profile. The turbo uses a traditional tooth profile where the BRZ uses something I've never seen before with the stepped profile. We suspect based on the oil pressures that this design is more efficient at low RPM creating less pressure and drag and at higher RPM it allows for more oil pressure.
The oil pump cover also shows some differences in the oil passages that appear to be done for the sake of more oil volume. The timing covers themselves are also different unfortunately. I'll let you guys see if you can tell the differences but it required welding, different sensors, and running the Hydra EMS with a totally different cam trigger setup.
At first I was really happy with the oil pressure I was getting. When cold it was the typical 110-120 psi but once warmed up we would see oil pressures in the 80s while cruising and it would hold to 70-80 psi to 9k RPM. Cruising would drop some but not a ton. Idle oil pressure was over 20 psi.
Now unfortunately after driving awhile and a few high power pulls, the high oil temps would drop the oil pressure and I would see cruise oil pressures around 50 psi and high RPM would barely hit 60 psi. If I did a few pulls, shut the engine off or 5-10 minutes while I did some Hydra tuning changes, I would then get nice oil pressure again (at least 70+ psi) for a couple high power pulls.
I have a video over on instagram if you want to check it out.
http://instagram.com/p/pgidojNvVB/
I do think adding a good oil/air intercooler would probably make oil pressure good enough for street use. Keep in mind I'm running an Element Tuning built motor, big valve heads, Hydra EMS, big intercooler, and running 20 psi on pump gas with a 60 trim. If you're not running over 300 hp your requirements will be less.
In the end this is no bolt on solution and absolutely requires a Hydra EMS as the standard cam/crank triggers will not work. The other issues is the crank trigger wheel is different on the 2015 WRX from the FRS/BRZ. I was really hoping this was a solution we could offer to our engine customers and something the community as a whole could benefit from but at this point this is a "race" only type of improvement.
Thanks,
Phil Grabow