FA20 Engine Oiling, Bearings, and Starvation

[Element Tuning]

Originally Posted by Panda Mao

nuuuuuuuuuuuuu poor FRS/BRZ R.I.P

No, no she's all good now The fire was last year and it's been rebuilt.

[Element Tuning]

So far I am not happy with what I'm seeing in terms of oil pressure.

Any engineers available to chime in on this pump gear design?


From what I'm seeing this oil pump was designed for efficiency/fuel economy as it doesn't jump right to the pressure relief like the EJ oil pumps do. This pump is RPM based and it slowly ramps up the oil pressure with RPM.

Now when my engine is cold I will see 120+ psi and then when warm it will cruise in the 60 psi range and get up to about 80 psi. Once the oil is hot it's around 40 psi under cruise and by redline it's about 65 psi. I took pressure readings in two spots and I'm seeing about a -10 psi difference between the main oil pump outlet (where OEM pressure switch is) vs. the oil feed galley plug at the crank/rod feed. The pressure at the crank feed is what really matters!


I wanted to test the pressure drop with the OEM water based oil cooler in place but I can't tell you if the pressure difference of 10 psi is due to the oil cooler or just the location but to be safe I took the oil cooler off for now. If the cooler keeps oil temps much lower well the 10 psi pressure drop may actually be insignificant and pressure may actually be higher with it in place. I'll let someone else test that.

I need to get business done and the prep our STi for Formula D/Global Time Attack this week in Atlanta so I don't have time to research this but if someone is willing, please look up the part numbers for the FA20 oil pump vs. the FA20T oil pump. I'm hoping Subaru uses a "normal" oil pump gear for higher pressure on the FA20T motor. A simple pump gear swap may solve this problem.

Here is the bottom line, 65 psi will never allow the rod bearings to survive on a 450+ HP FA20 motor. These pressures are recorded at street temps and not under racing conditions. Frankly knowing what I do on our EJ motor race program bearing skimming occurs in the 60s and failure in the 50s almost instantly. With an NA motor or even a supercharged setup under 300 whp, I don't think the OEM pressures are something to worry about. The reason is that the power delivery is linear in both cases and therefore the linear nature of how this oil pump works I don't see it being a deal breaker.

Now a turbocharged setup hits peak torque much earlier in the RPM range and so peak oil pressure is needed much sooner (you can't wait until redline to see 65+ psi).

Is anyone else recording their oil pressures and if so what are you seeing under various conditions?

Thanks,
Phil Grabow

[CARNZ]

The FA20DIT oil pump on the new WRXuses 14mm rotors instead, maybe that will help enough with oiling? I don't know many more details about it at this time other than the size

[Element Tuning]

Originally Posted by CARNZ

The FA20DIT oil pump on the new WRXuses 14mm rotors instead, maybe that will help enough with oiling? I don't know many more details about it at this time other than the size

Well that makes a huge difference! Any part numbers by chance?

The gear while it may fit in the existing timing chain front cover it would protrude out of the housing so either the entire front timing chain cover is different or the back of the oil pump cover and gears only are different.

[CARNZ]

Technically the oil pump is "not serviceable" so its only sold as a unit, but once I'm back from lunch I'll get the chain cover asst part number from the parts guys

[Element Tuning]

Originally Posted by CARNZ

Technically the oil pump is "not serviceable" so its only sold as a unit, but once I'm back from lunch I'll get the chain cover asst part number from the parts guys

You the man, thanks!

So it might be an entire engine cover along with the pump.

[CARNZ]

13108AA140 is the PN for the dit chain cover asst with the larger oil pump

[Element Tuning]

Also I don't know how readily available they are but the JDM RA EJ motors came with a 12mm oil pump that used a standard gear profile. It's possible if we can source one we can test fit that into this pump housing.

[blackfireball5]

This thread has so much valuable information about our engines and oil. Love it. Keep it up!

Sent from my Nexus 5 using Tapatalk

[Element Tuning]

Originally Posted by blackfireball5

This thread has so much valuable information about our engines and oil. Love it. Keep it up!

Sent from my Nexus 5 using Tapatalk

I'll be fitting a larger oil pump hopefully by the end of the week. I'm hopeful this will bring us up to adequate oil pressure which will solve the issue for 90% of most users.

We still really need a dry sump but I may test this pump and one more device before going to a dry sump. I'm hoping ARE will design the oil pan before I have to

[DBW]

@Element Tuning have you been able to confirm the DIT pump is larger and fits?

[kiichiro]

Tell us more

[Element Tuning]

Originally Posted by TopSpeed

@Element Tuning have you been able to confirm the DIT pump is larger and fits?

No I won't have an answer to that until next week unfortunately.

[ATL BRZ]

Originally Posted by Element Tuning

One of the only oils that stays in "grade" is Redline and it's why we use it for our EJ race engines and will also for the FA20 motors.

You guys should try Miller's Nanodrive racing oil, I think it's a perfect match for this car.

It is more durable (tested to last at least 1600 race miles on one fill) and offers better friction reduction and bearing protection than other race oils.

The FA20 responds very well to it and so do other dedicated race engines.

I've been using it for a while now on and off track. Great stuff.