I have an LS2 block, bought from Summit, with a 24X crank, '10 LY6 rods and pistons, 3-bolt Tick cam with LS2 1X cam sprocket with the tan sensor, 317s (already had them with trunions, springs and stock-size Ferreas), ATI balancer, TCI flexplate, 9.5" PTC, TH400, Holley HP with a E70 mix.

Oil pressure dropped a little and after a pass, I was seeing 20psi on the return road. After 2+hrs in the pits, fired it up again and had 50psi, so I decided to drive it home (11 miles). Anything over 2000rpms, I could hear the engine rattling and the oil pressure stayed in the 30-35psi range all the way home. Knowing it would have to come apart but not for a while, I drained and flushed out the E70, put in some pump gas and curiosity made me fire it up. 60psi dead cold, only 5 less than normal. After it warmed up, I revved it up and the rattle was gone, even up to 3000. Now I was really curious, so I pulled it and broke it down.

#2 and #4 rod bearings were spun, with absolutely no damage to #1 and #3. It was almost as if an imaginary line was drawn in the middle of those journals with orders to F**K up 2 and 4 but leave 1 and 3 untouched Some of the other rod bearings showed signs of slight hammering on the top halves. I was commanding 11.4:1 AFR and the combustion chambers were completely black as if they were spray painted. More on this later. On to the mains. 2, 3 and 4 had more wear than 1 and 2, but the forward edge of #2 had more wear. The oil grooves on the thrust bearing were completely worn down, BUT, only on the main cap half!! The top half had just a little wear. The thrust area of the crank has heavy bearing overlay, but not all the way around. The position of the overlay lines up with the bottom half of the thrust bearing when the crank puts #2 and #4 at TDC.

My unprofessional opinion from the evidence is that #2 and #4 were misfiring against the crank rotation, causing it to flex and hit the bottom half of the thrust bearing and the front of the #2 bearing. What I don't understand is why was only #2 and 4 misfiring? What do they have in common?

Back to the overrich condition. Couple weeks ago when I did the E70 mix, I unknowingly used some 110 leaded gas for the mix. Did a short WG spring pull (5psi) on the backroads and 3 14psi runs at the track. Car ran decent for 14psi and the plugs showed slight peperring on the porcelain but no signs of heat and only 17* timing. Peperring was minor, maybe 5 or so spots on each plug. Didn't think much of it until I discovered it was a no-no to use leaded gas. Next time out with the proper mix is when I lost oil pressure. Before pulling the heads, the datalog showed no indication of anything unusual. After I saw the heads, I went back and saw that the Holley was correcting between 30-39% all through the pass. I am concluding the WB was incorrectly reading lean and the Holley was compensating, so it was dumping in lots of fuel to maintain the 11.4:1. Could this be a contributing factor? Again, why just #2 and 4? Crank reluctor? Cam sensor? Near hydrolock? ???

At this point I am probably rambling but wanted to make sure I did not miss any detail that might be useful. Appreciate any feedback.

 

Rod big ends could have been out of round and by mere coincidence that crank journal could have measured the largest (least bearing clearance or most interference)
Also that second main being right in front of the thrust main, could have the highest bearing load. And/or most deflection under crank power/twist.... It then would feed bearing **** to the rods

 

in for pics of carnage

would really help with diagnosis to see the body please

 

Did you have the block, crank, and rods checked by a competent machine shop?
What were your clearances?
Who assembled the motor?

 

After receiving the block from Summit, it was checked by someone very competent. Bores were impressively consistent, all coming in within .0001. Crank was magnafluxed, checked for straightness and cut 10/10. Wanted to open up the clearances, so I consulted with Kings and their recommendation plastigaged at .0028-.0029 on both rods (new bolts) and mains. I did the final assembly. Oiling is a Melling 10296, VR1 20W50, remote-located HP1 filter and Moroso pan.

Crank was definitely flexing. Turned easily even when disassembling it the other day. I will see if I can snap some pics tomorrow.

Not going to rule anything out as the cause. Still trying to find a way to test the WBO2 sensor as I strongly suspect it. If anyone in the Orlando area has a Dominator or HP, would appreciate a little help using it to do a free-air test.

Thanks.

 

Here are some pics. Don't know how useful they will be.

Rod journals 2 and 4



Rod bearings 2 (left) and 4



Main caps (#1 at the bottom)



Top half 1-3



Top Half 3-5. Note the wear on the thrust area.



Thrust area of the crank that would be facing the bottom half of the thrust bearing when #s 2 and 4 fired. Note the bearing overlay.



Thrust area of the crank that would be facing the top half of the thrust bearing when #s 2 and 4 fired. Note the position of #4 rod journal. Note the bearing overlay or lack of, compared to the pic above.

 

So you used a used older crank and used newer rods and Pistons? Did you have the assembly balanced? I heard that there was balance issues with the newer style rods on older cranks.

 

I seriously doubt it has anything to do with air/fuel ratio. How do the pistons look? they should look fine. If there was any kind of pressure wave (sudden pressure spikes that damage rod bearings) the cast piston would likely show signs of deterioration, but I suppose anything is possible. I am not discounting any theory, but sometimes the most obvious answer is the simplest, ...

I think you have an assembly issue. First, from a daily driver perspective, .0028 is huge. I would have kept it around .0020 mains and .0017 rod (they are rarely the same) if I were doing a street/forged piston type deal, and even smaller with a cast piston. I have no experience with such large clearances so maybe what you did really is fine, but that is typically not a number you associated with street build/daily driver bearing clearance that you could expect to cold start an engine twice per day for 200k, not with .0028". Sorry if I misunderstood and this is not a daily driver (but then why the cast piston?) Second, you cut the crank, but did you bolt the new 10 over bearing into the block and dial bore gauge it?

To reduce/control parasitic loss the OEM uses a tighter range of clearance, and lighter weight oils, restricting max rpm performance (racing stuff) but improving engine longevity. For max performance, a forged piston is used. If you have a cast piston, there is no max effort, i.e. you will want an OEM clearance, and less-than-max effort RPM potential (and small lift camshafts etc...) since the project is budget cut at the level of the piston.

Shorter post:
I think somewhere in the cutting of the crank/machine work done/individual clearances/tightening/lubricative surfaces there is more likely to have been a mistake, than in the computer control/tuning.

 

I tore down an engine with a similar issue 2 days ago. Lost oil pressure and always had low PSI according to the owner. Only lasted about 1500 miles.

So far I have concluded the engine was dirty during assembly and the clearances were not set properly. While mine did not have any spun bearings, it had the 3 and 6 rod bearings go through the copper.

I am wondering if the 2 rod bearings that are the worst were not seated properly during assembly.

 

Thanks for all the feedback. Good information moving forward.

Rotating assembly was not balanced. Car is not a DD. It's just a toy that see the occasional cruise with a goal of being driven to/from track and run hi-8s. No street racing or competition. No reason why this combo shouldn't achieve that.

As for the AFR issue, the Holley opened the spigot because it detected a massive lean condition. 35+% is a hella lot of E70 to dump into the engine and the combustion chambers and piston dome pics show that. Whether it is the cause or not, it is a real issue and I still need to find the cause.

 

This confuses me. WHy would you allow closed loop operation during WOT? You can NOT depend on any kind of aftermarket "auto tuner" tool to give your engine the fuel it needs at WOT. I am most vexed by this, even more than your use of a cast piston in what appears to be a tri-metal bearing, ultra large clearance drag racing application.

Never let the ecu decide how much fuel the engine needs. To tune something like this, you take it to a dyno, and compare your in-car wideband with the dyno's wideband, before turning up the boost at all. In fact you run it with the wastegate wired open first, at WOT, to determine baseline fuel curve features (you make a base map at 0psi) and use that basemap to determine fueling for all other load points (since engine VE follows the same general path as boost pressure rises, until the compressor gives out at least). Then gradually raise boost, with everything too rich (10.8:1 region should be easy to math from 0psi at any boost pressure) then gradually lean it out to where you think it should be (depends on altitude, engine, compression, piston material, application, and so forth)


And here are some general drawbacks from "dumping too much fuel" (these are what can happen to the engine)
1. hydrolock (takes ALOT of fuel, very obvious damage, and I've seen it happen) but this is not your case, I am just showing all the possibilites.
2. Washing the oil from the cylinder walls. This can take YEARS of daily washing to cause any permanent damage, but it will eventually lower compression ratio in some engines with OEM internals in my experience (could take 5-7 years to show up)
3. large backfires/flames (like running an ignition cut, "not good for street cars") this can cause bent valve/valvetrain issues if it happens at high RPM with a weak valvespring. Again, does not pertain to your situation.
4. BLow out the spark, no detrimental effects really just an obvious miss/stumble from being too rich.

5. And last, that I can think of, running too rich can pollute the engine oil, making it less effective at lubricating parts. If you managed to flood the oil with fuel and try circulating more fuel than oil through the bearings, well that does not work well. This is the only possible feature I can think of that may have had anything to do with your failure. You should have been able to detect a higher oil level (you didnt put 10 quarts in etc... )and a distinct fuel smell in the oil if this was a culprit/cause, and furthermore you would have had to run it like this for a while (depends how gradual/sudden you polluted the oil of course).

 

I'M BETTING A impropperly installed oilpump.

 

Interesting. What led to this conclusion?

 

Sure does look like a crank issue, possible deflecting. How is the thrust spec? Im in Orlando, what machine shop did you use....you can pm me. I use some guys in Sanford and haven't had a problem yet.

Bearing specs are loose but not god awful.

Did you happen to install the rod "backwards"

Bad oil pump would hurt everything not selected pieces.

Lastly - just throwing this out there. How are the cam bearings in associated bores?

 

Are you using the reinforced oil pan? Factory oil pan is structural to help alleviate some crank wobble. Might explain the flex and thrust bearing wear.

You did use ARP main studs right?

How did the cam bearing look? That should tell you if the oil pump was feeding properly, then an oiling issue would be due to blockage in the galleys. Or a stray shaving found its way to the bearings.

Is it possible your converter ballooned and pushed the crank forward? Autos are magic to me so just guessing.

For the black chambers, its probably due to excessive fuel and not enough timing. I do that on purpose in the STI to keep flames in the exhaust for anti-lag.... not good for any parts and definitely hurts the turbo. Think about it as burning fuel the entire power and exhaust stroke and still burning on the way out.

 

I'll try to resond to the last 2 posts.

It is an SBE, including all the bolts.

Crank was done by Auto Machine, downtown Orlando. It was magnafluxed, checked for straightness and cut 10/10.

Oil pan is a Moroso. Lots of people running similar non-OEM pans.

Oil pump is Melling 10296. Double-roller spacers were installed correctly. .002 gears to case clearance. Other than the trash, no other signs of damage.

Cam bearings are all good.

Rod/piston assemblies were never seperated and rod halves are scribed to avoid possible mixup.

No evidence that converter was pushing the crank and if it was, why wipe out only bottom half of the thrust bearing? TH400 has a .100 restictor in the cooler passage port and the cooler line has a fitting so I can occassionally check the pressure.

Been running basically the same tune for a while with roughly 17* @ 17psi. The excessive fuel is from the Holley correction and that has never happened before.

Not ruling out any suggestions. Just looking at my setup to each of the suggestions/comments.

 

Is the darkest piston in that picture above, one of the rods that ate the bearing through the copper?

 

No. The pic shows 2,4,6, L to R. 2 and 4 have been "handled" more, so the outside edges appear a little cleaner.

 

I believe there was some contamination during assembly But can't define if that was the true cause, I guess I would have to agree in general that it was stupid rich.

 

Well I'm out of ideas lol

sub'd for future resolution