Raf99

Well, i'm at a lost for answers and figured I'd ask in here before we rip this engine apart. To start, this setup has been running well for 5+ years now. Not a single drop of oil burnt or lost, not a single issue with the engine ever which is expected as it was sent to a machine shop and tuned by reputable shop. I'm hard on it and only street drive it, but it was built to take the punishment. Running low compression and 400HP with the following bits: (built bottom end)

JDM H22A engine
Darton sleeves
Eagle H rods
Arias forged pistons (8:5:1)
Cometic head gasket
ARP main studs
Cometic lower engine gasket kit
Endyne oil pump
EGR/Canister full removal
GT35R Turbo (.70 compressor, 56trim) w/ oil and coolant lines
S300 V2 ECU
Oil pressure gauge
Oil catch / valve cover 2x10an fittings setup
etc....

Two -10AN fittings off the back of the valve cover to a catch can which does not drain back into the block. Recently started seeing massive amounts of oil going into the catch can (1 cup or more on a 10min drive, not in boost). So we did the obvious and ran a compression test and leak down test. But numbers came back fine........

Compression:
#1 - 160
#2 - 170
#3 - 160
#4 - 165

Leak Down
#1 - 0%
#2 - 5%
#3 - 2%
#4 - 5%

So I've been reading and researching for two days. Some thoughts.......
- The H22A has a oil orifice which connects the head and the block oil passage. I know this has a rubber O-ring, but does it act as a restriction?
- One youtube video pointed out that the cam shaft plate bolts actually go into the oil passages that lead to the cams. If one of these bolts was loose or broke oil would leak out where it shouldn't. Checked, no issues.
- Checked the bottom of the valve cover to ensure the baffles are still intact. Looks fine. (OEM valve cover with AN fittings added)
- Oil pressure has no changed
- PVC is blocked off
- Spark plugs look fine
- Car runs fine for power
- Can the oil rings be bad but the compression rings be good? (I'd think this would show in a leak down test)

The amount of positive pressure it seems in the head is far more than it should be, by a lot! And............ i'm lost for answers atm. Obviously something is wrong....

Raf99

Well I appreciate the honesty and no guessing. I'm going to rip into the block but most experienced I've spoke with say it could be...
- cracked ring / piston
- bad valve seal (only under load)

I ran the catch can hoses to a clear jug and ran the car (on jack stands). No oil. It's under load that this is happening / 15PSI , all vacuum / high head pressure. Doubtful it's the oil orifice.
While the 5 years without this issue was sweet, now I can fill the catch can on one outing. So something is broke. (makes me wonder why some cars needs a oil return line though while others do not)

Cheers.