club.liberty.asn.au

Just did an ej207 ver10 sti shortblock build on my 07 jdm legacy gt with reused stock U20 heads. Still under break-in period(500miles). Did a cyclinder compression test recently and got these values:
Cyc 1: 105 psi
Cyc 2: 106 psi
Cyc 3: 110 psi
Cyc 4: 108 psi

Are these within limit or too low for a new sti shortblock build? Could the compression readings go higher with more miles as the breakin mileage reaches 1000-1500 miles or i need to look into my cyclinder head valves or piston rings? Car seems to run fine, no excess oil or coolant consumption. Haven't done WOT runs yet, just 4.5k rpm and under for now.

There’s so many variables related to technique of compression and leak down testing, it might be more relevant to simply compare cylinders and since none are low, call it good and concentrate on your datalogs prior to going for full boost.
Eg are your fuel trims in spec, is cruise afr and VVT correct, is your IAM steady and at the max value?
Feel free to share links to logs you have uploaded to the cloud for comment.

How to make and share useful diagnostic data logs:
viewtopic.php?f=6&t=36932

During my rebuilds running in, I had to keep logging and health checking before I could use any real load due to many issues related to things missed during the install. All good now tho…

Engine health checks, inlet, exhaust pressure tests:
viewtopic.php?f=6&t=36513