1SIKZ31

iTrader: (5)

Hey guys, I have had my LS1 for about 2 years now, since coming out of the machine shop, probably about 15,000 HARD miles... All Motor, Nitrous, and Now Boost.
The important Bits:
Melling Standard Volume Oil Pump
346ci LS1
Clevite Bearings, no idea on clearances since the machine shop put it together...
Anyway...
Oil pressures at cold start were ALWAYS 38-45psi at idle. (AEM Oil Pressure Gauge, Electric Sender)
2000+rpm Cold Motor - 50+psi oil pressure...

Warm Idle was always 25-30psi oil pressure (Fully warmed up)
2000+ RPM was always 40+psi oil pressure (Fully warmed up)...

Its been ROCK SOLID for about 2 years like this.. beating the **** out of the motor, changing the oil and filter every 1500 miles with Mobil 1 5w30 Fully Syt.

Now, last weekend I went out racing and im at around 650whp on this particular night... I did about 3-4 races back to back... usually I never do this... I always give it cool down time.
Coolant temps after the 4th run were 213 degrees (AEM Water Temp Gauge)

So nothing out of the blue and everything was rock solid...

Came to the stop light, looked at my oil pressure gauge and almost **** myself! Idle was about 7-12psi and when I revved it to around 2,000 rpm it was about 15-20psi, WAYYYYY lower than usual.

*The engine is not making any abnormal sounds.
*The oil level is FULL and nothing is leaking at all, not even a single drop, literally.
*The car runs and drives fine... of course I limped it home.

I connected a Mechanical Oil Pressure Gauge to my Sending unit adapter piece above the oil filter, to rule out the sender being out of whack...
100% same readings. Low Oil pressure, I got about 14psi of oil pressure at HOT idle. (190 coolant temp and heat-soaked quite a bit...)

I did notice some shiny-ness in the engine oil when I pulled the sending unit adapter piece out, it definitely looked like bearing material.

Question is, what do I do at this point?
A few people are saying my oil pump probably took a ****.
But I personally think some engine bearing somehow got excessive clearance in it or something, I have no idea...

Obviously the safest bet is to pull the motor, get it checked out at a machine shop... But I posted here to see if I could get any insight, maybe I'm just posting because I'm in denial IDK.

Help!

ABQ99TA

iTrader: (17)

Bearings for sure. Sorry but if you caught it quick it might be an easy check and new bearings. Good luck

gMAG

iTrader: (1)

Oil pump material should have been caught in the filter, so it prob isn't the pump.
Remove the oil filter, cut it open and inspect for further evidence.
As you already know, the engine needs to come out.

1SIKZ31

iTrader: (5)

****.
Ok... this sucks.
Such is life. lol.

Dumb question: How can something like this happen?
Over-loaded engine bearings? (Rod, main bearings...)
or maybe a Cam bearing that's somehow coming apart?

I know that **** happens, and I won't know the answer til I pull the motor, but how do bearings just all of a sudden **** up in the middle of driving?
Minus a "Spun" bearing, how do bearing clearances increase so significantly I lose a ton of oil pressure.

Wow I sound like a noob, I couldn't word it right... I guess I have limited knowledge lol.

Exidous

iTrader: (11)

Even with perfect oil pressure for the life of a motor the bearings can still wear out. Old motors will usually run better on thicker oil due to the bigger gap in the bearings. 5w30 seems light for a "HARD" mile motor. Did your builder suggest 5w30? The weight oil should have been selected based on the use of the motor and the clearances it was built with. Also keep in mind that many race motors get rebuild after every race.
Side note: My RX-7 is crazy with "only" 420whp. I cannot imagine a Miata with a boosted ls1. 300 more HP and 400 less lbs......Must be a wild ride.

quik95lt1

iTrader: (7)

time for a refresh........id ask your machine shop about the clearances and the runout of every journal and housing bore in that motor......2 years is not a long time for a hot street motor.....i went 3 years on my 8k+rpm 700hp race motor and all my bearings looked like brand new when i ripped it down......sounds like something wasn't done correctly in the 1st place.....many times machine shops like to run clearances TOO tight.....espically in a high hp power adder motor where hi heat is commonly seen i run a hair looser with thicker oil......move more oil through the bearings to keep them cool and leave more room for thermal and debris issues........ .0025-.0030 is not an issue on rod bearings and even a hair more on the crank.....my race motor i run .0028-.0030 on rods and .0029-.0032 on mains........no need for crazy oil press either, im running 55psi max at 8000+rpm with 0 issues....the idea you need 80+psi pressure is old school and belongs in the same box as the 3/4 race cams and double hump heads lol

good luck!!

gMAG

iTrader: (1)

Also, try removing the valvecovers and see what's going on there.
This might be one of those, "what came first, the chicken or the egg?" things.
I, too couldn't figure out whether a bearing dissolved, and then pressure was lost...or whether the barbell in the rear oil galley (which was found "backed out") caused a catastrophic pressure fail.
My thoughts went in circles, as if I could somehow resolve the problem by reasoning it out.
Either way, you know you'll be back on the road!

Old Geezer

iTrader: (3)

"How can something like this happen?"

Detonation can very well beat the brgs into "submission".....The N2O may have gotten the process started. Then, the boost finished it.
Have you been monitoring the plugs???
If so, what are you seeing there?

jthurik

Pull the filter and cut it open

If there is metal in filter pull motor

no metal replace oil pump

for the heat I would also use brad penn or ames oil IMO

I was at 230 watertemps and 217 oil after these runs car cooled down on drive back to 208 water and sub 200 oil it was humid that night my Tranny never got above 210.

1SIKZ31

iTrader: (5)

****!!!!!!!!!!

motors coming out in 4 weeks

Che70velle

iTrader: (6)

Yeah, the "and now boost" part of the first sentence was a dead giveaway. You beat the rod bearings out of her. You've gotta set them up for boost from the get go, to run them real hard and expect em' to live. Time for something bigger and badder. As if you need it. Were you on the street or track when you hurt the motor?