1SIKZ31

iTrader: (5)

Iphone 5 pics so give me some slack...

Anyway guys, 346ci LS1 fed by a 76mm Oil-Less Rear Mount Turbo on my LS1 Miata...


After this race (See Link Above) the engine lost 70% of all of its oil pressure... and I parked it and tore open the Oil Filter and found **** loads of Metal in the filter... Tore apart the motor and had it rebuilt...
The crank cracked. My machinist thumped it on the ground and it just made a loud "THUD" and then he showed me 2 other cranks (Good cranks) and when they are touched against the ground they go "Clingggggg" and he said my crank just "Thuds" because it is cracked.

Anyway... Machinist said that this looks like severe detonation pounded out the bearings... other people are saying that its from in-adequate oil supply such as high oil temps and/or shitty oil (Mobil 5w30 fully syn)
and by the way the old motor was:

Stock Crank
Stock Rods
Clevite Bearings (No idea which style or grade, sorry)
JE Forged Pistons (Stock CR) <-- NO DAMAGE TO PISTONS!
and the rest of the motor is irrelevant to this thread...

Anyway, what do you guys think happened from the pics?
The car was on 12-13psi boost on 93 Octane Only at like 12-13 degrees of total timing under boost (So it definitely wasn't a timing related knock!)

Does it look Oil Starved?
Detonation?
Any other ideas?????

KCS

iTrader: (20)

What do the pistons look like?

boostit5.3

iTrader: (3)

if the cam bearings look trashed it was probably an oiling issue. how did all the other bearings look? maybe you got some bad gas that caused the detonation??

blueshifty

The cam if advanced IS relevant to the thread. The other part of that also would be if your cam has you spinning high RPMs and I saw no mention that you balanced your rotating assembly so vibration could've played a part too. The oil you were running is great quality and I doubt it was the issue.

lt1pwr1

iTrader: (1)

I'm no expert but it definitely looks oil starved to me. You trashed out what looks like all the bearings (judging by the ones you posted and the crank journals.

I would guess that maybe your crankshaft cracked after the oil starvation? Not really sure but maybe the sudden seizure of the bearings put too much stress on the crank and it cracked.

I'm curious what a sponsor has to say - someone like HKE, TSP, etc.

Atomic

iTrader: (37)

If the pistons looks perfect I doubt it was detonation. Looks more like an improper shortblock assembly with not having proper clearances or and/or an oil pressure issue.

ZDER

iTrader: (3)

+1 ....did it have arp rod bolts or something aswell?

1SIKZ31

iTrader: (5)

The Engine Did have ARP Rod Bolts on Stock Rods, Yes.

The Pistons are NOT Damaged at all but maybe its because they are Forged so much stronger against detonation to damage. (Pistons Perfect!)

The engine was run HARD for 2 FULL years, racing, racing and more racing, I beat the **** out of it but ALWAYS changed the oil every 2000 miles and always used Mobil 1 Oil Filter. It's been through nitrous, turbo, all motor, you name it! As well as 4 different cam set-ups! What i'm getting at is that I doubt it was a install issue...

No idea if the cam bearings were hurt. (I didn't ask the machinist)

the rotating assembly WAS balanced and it came with the motor (sheet stating they balanced it).

Oh and the engine was running a Melling Oil pump, not stock. (Idk if that matters any...)

Any clues?

SS10Tech

+2 Fully Agree

Gray86hatch

iTrader: (83)

What oil pan. Prob sucked the pan dry. Stock pickups need help to get the oil into the pump and the pan size is a issue also.

Tim

Gray86hatch

iTrader: (83)

Improper assembly is unlikley due to the fact it was running for 2 years.

Tim

kossuth

iTrader: (12)

No expert, but looks starved. May have been a pump failure, or maybe like others suggested maybe you pumped the sump dry. Just curious what melling pump did you have and what bearing clearances were you running if you know. Also wondering what pan you had.

1SIKZ31

iTrader: (5)

Oh!!

I forgot to mention that!
Its an F-body oil pan... thats been cut up and modified so that it fits my Tubular V8 Crossmember in my Miata... In other words, it now holds about 1/2 quart less oil capacity than stock... Its like... 5 quarts fills the entire motor and the dip stick reading full...

If this is the issue... What should I do?
there are ONLY 2 options:

1. Run more oil in the pan and hopefully it doesn't create air pockets from it being to high and the crankshaft churning up the oil...

or 2. Run an external oil cooler that attaches to the original oil filter housing on the pan so it gives it more oil capacity and allows the oil to heat up less as there will be more oil (hopefully a quart more)

This section was cut out and then welded flat so that it clears crossmember...

Atomic

iTrader: (37)

Yea, not an assembly issue since its been running for 2 years.

How about a dry sump conversion?

A.R. Shale Targa

iTrader: (2)

Those look like Clevite P bearings which @ 800 plus horsepower were just
WAY beyond their intended design. You need hardened bearings in order to
cope with the lbs. per square inch of bearing load that your combo delivers.
I'd consider a forged Lunati crank which will have a lot less deflection and
some Federal Mogul bearings where the mains have 3/4 groove for an
additional 90 degrees of crank rotaion main oiling and furthermore the mains
feed the rods so happy mains = happy rods. Can NOT overlook a quality
harmonic balancer to dampen the rediculous harmonics of a high horse combo

kossuth

iTrader: (12)

Well, kinda a tough call there. I had two motors let go in the past due to oiling issues from what I eventually figured out was a modified pan issue on my s10 pickup.

Think of it this way, the GM engineers that designed the factory pans for these motors put hundreds of hours into oilpan design. I suspect things were done a certain way for various reasons. Now, I am not saying your pan is the culprit here being I am not qualified to make that statement, but I will say that it is not outside the realm of possibility if it was indeed starved and you had the pan full and the pump didn't fail. I will say in all fairness that 100s of folks have modified their pans with good results, but there are also some that have had issues. If you think the sump was pulled dry then you have a few options. Not run so aggressive a pump, or get more capacity. Both of those options may challenge you fitment wise or engine build wise. Windage isn't a good thing so I would be super cautious about overfilling. Maybe a ls2 pan fits better? Maybe it has nothing to do with the pan at all also. Whatever it is it sucks because nothing like this is ever cheap to fix.

1SIKZ31

iTrader: (5)

Yea this sucks... Whats bothering me I'm getting different answers from everybody!
I do understand that NO ONE will 100% know what actually happened...

But here are the possible culprits:
1. Harmonic Balancer is crappy (Its aftermarket 25% under-drive and it DOES wobble a bit more than what I would like...
2. Oil starved from the oil pan due to heavy lateral acceleration or possibly cornering which F-body pans are known for being crappy with!
3. Bearings were wrong grade.
4. machine shop error <-- I doubt this because motor has been running 2 years strong!
5. ????

Holy crap lol!

prokilllsx

Sounds like a combination of Numbers 1, 2, and 3 on your list but mainly 2 and 3.

SS10Tech

Tim,

I do agree it does not seem like a thrust bearing or major clearance problem at the time of assembly. However looking at the wiped mains i believe foreign particles could be to blame which is hard to tell from where, or when. By the time this happens the problem that originated has been happening for quite some time. I am a bit surprised to see crank deflection as a possible cause. I was under the impression these cranks have ran in 1000RWHP builds before without any issues of concern. I do question to tight or to loose of a clearance limiting hydraulic oil film efficiency to separate the main bearings from the crankshaft, mixed with sucking the modified oil pan dry causing overheating, mixed with particle contamination which further eliminates the oil flim hydraulic effect. All of this is possible to be the answer, however i would look at the oil pan and bearing choices as the most obvious that separate this particular failure from other platforms.

Quick question , were oil temps ever a problem?

blueshifty

When you go back with it, I'd go with high quality bearings, and ATI super damper and a forged crank. You were pretty close to the limit on the stock bottom-end anyway. I am not really sure if the oil pan issue played into it, but as others have mentioned a dry sump would likely be your safest bet.