Need some help with engine diagnosis

[j87w]

So I have a Redtop SR20DET that has been rebuilt with .20 over CP Pistons, stock rods, crank, and acl bearings. It also has Tomei 260 camshafts, FMIC, GT2871R .64AR, Nismo 740cc injectors, DC Sports Manifold, Exhaust, AEM EMS w/ MAP conversion. The problem all started at the dyno. I had ran the car about 2 hours idleing and driving around slowly. Then I took it to Motiva Performance for tuning in ABQ, NM. They tuned the idle and part throttle and got about another 2 hours on the engine. At this point the engine was using no oil, had good compression 150PSI across the board and ran great. Then we let it cool for an hour and fired it back up for tuning for boost. At 12 PSI no smoke no oil out of the breather and with a safe tune made 290 WHP uncorrected (at 5600ft elevation, 103 degree room, 91 octane). The plan was to have high boost no higher than 20 PSI. So we did a pull and bumped the boost a bit each pull to check A/F, knock, ect. We made it up to 17 PSI and then we got a bit of oil out of the T in the valve cover that dripped on the manifold. We killed it, pulled all the plugs and checked them. Everything was great. We started back up and it started right up and ran fine. Nothing went wrong as far as A/F, Knock, ect. We made a pull at 12 PSI and now had oil coming out of the breather then. So I towed it back home and checked the compression. Hot the compression was #1-120, #2-110, #3-118, #4-120. The leak down was #1-12%, #2-22%, #3-32%, #4-13%. The car was broken in on Mobil Non synthetic. The ring gaps were .020 top ring, .024 middle ring, .015 oil rail rings. All rings were gapped and installed to CP Spec. I tried installing the OEM catchcan and still had oil out of the breather. So I tried it with no line on the block and no line on the T and got oil out of the line in boost. Oil level is good, no oil in coolant. The only weird thing is that when cold and running pressure straight from the air tank into the cyl most of the air comes out of the other spark plug holes rather than the oil cap, dip stick, ect. The machinist thinks the rings may not be seated but Ive tried going up and down the highway revving it to 4kRPM and letting off about 20 times and everything is still the same. Im not sure how we would of cracked a ringland or broke a ring at the boost level and amount of timing it had in it.

Any ideas guys?

[steve shadows]

Your Compresion is low

what is your Compression Ratio right now? are you 100% sure you know what it is and is correct?
sounds like you just have really low compression and that sit

[j87w]

The cr is 8.5:1 static. It had 150 psi per cylinder when the engine went into the car. What I'm really lost by is why there is oil out of the breather at 12psi when there was not before. I'm thinking a ringland or ring failed but would like other opinions.

[j87w]

Any other opinions?

[PinkPanther]

Did you ever properly break in the engine? As in stay out of boost and high rpms for like 500 miles after the build?

[j87w]

No. Not for 500 miles. I would say it had about 4 hour on it before high rpm low boost

[TheWolf]

Thank you. You have actually provided real information. Assuming your machinist was competent, your break in was fine.

Ok your #3 has a good bit of leak down. Listen to where it is leaking past. You should hear either rings/or valve seats. Your #2 has the lowest compression but the a better leakdown. Check it as well. More than likely your getting blowby past those rings if your getting a steady flow of air and oil out the breather. This could be from either a broken ring on install or to rough a hone surface which is pretty hard to do. Do you know what stone your machinist honed it with and if he performed a plateau hone on it afterwards? You didn't happen to install total seal rings did you?

[j87w]

The air is all coming from the breather on the block. And No I'm not sure about the hone.I'm almost positive it couldn't of happened when it went together. I made sure everything went together easily and to cp spec. Also I'm running the stock cp rings just gapped to there spec.

[TheWolf]

It's doubtfull that it would have broken in that quick run on the dyno. When installing these pistons, it's important to place the piston in the hole. I prefer a band ring compressor over our clamp style for these rings. Square the compressor against the deck surface then tighten and compress the rings. I guess I should ask. Were the 150psi number and the 110 psi numbers taken with the same compression gauge? Second since I don't have CP rings in front of me but are they like keystone shaped? IE did you put them upside down on a piston?

[j87w]

No that was not a mistake in compression readings. They were taken with the same gauge. Yes the rings have a certain way to be installed and were installed that way.