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Oil pressure Questions/Concerns

790 Views 18 Replies 3 Participants Last post by  yaggs
Hey everyone, need to pick your brains:

Earlier this year I rebuilt my stock k20a2 (new oil pump). I used honda bearings on the crank so clearances were pretty spot on. The rod bearings I needed were not available from honda so I went with king xp standard rod bearings. The clearances were on the tight side of specs. I could have gotten a second smaller set to pair with the standard, but this would put me on the loose side of the spec. I opted to do one set of bearings and stay on the tighter side.

My current oil pressures with Mobil One 5w30 are (at 185 deg F oil temp):
32 psi idle (975 rpm for MM vibrations)
82 psi at 3k rpm, 87 psi at 4k rpm
At cold start-up and regular driving it gets to mid 90s psi

I’ve noticed the oil pressure relief valve opens around 80-85 psi (which coincides with info I’ve found). Basically, anytime I’m over 3k rpm it is open. I’m not sure on how the pressures are supposed to work in a healthy k20a2. I would assume that the valve should be closed when the engine is up to temp (throughout the rev range).
  • Am I over thinking this? Is it totally fine that my relief valve is open during most of my drive cycle (I’m on highway to/from work everyday @ around 3.5k to 4k rpm). My gut says that 100% flow at 70 psi is better than a “relieved”, “bled off”, or “bypassed” flow at 85 psi.
  • I’m considering trying out 0W20 to see where my pressures sit. This brings up a few concerns like film strength and the effect on the looser clearance items like camshafts and crankshaft.
  • I’d rather not change out the rod bearings if not absolutely necessary.
What would you all do if it was your DD?

Thanks everyone!
1 - 1 of 19 Posts
you can mix the King XP bearing shells to get intermediate sizes, e.g. STD on top and 0.001 on the bottom.
1 - 1 of 19 Posts
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