Bearing Damage Ls2 403"
 

I'll start off by saying the motor is currently at the machine shop waiting to be torn down to see what the true damage is.

About 3 months ago after doing some all motor WOT tuning I noticed my oil pressure was dropped very low-15-20psi at idle and 35psi at cruise and 40-42 at WOT. This concerned me as I knew something was up. I drained the oil and cut open the filter to discover this:


https://cimg6.ibsrv.net/gimg/ls1tech...6009f3e163.jpg

https://cimg7.ibsrv.net/gimg/ls1tech...c6e0ffe42c.jpg

https://cimg8.ibsrv.net/gimg/ls1tech...8cba68fa14.jpg

The motor runs strong with no knocking or unusual noises or loss in power. Obviously a bearing or more is getting chewed up but not sure if I'm looking at main bearing damage or cam bearings... I should hopefully hear from the machine shop by Friday to see what the damage will be and will keep this thread updated.

For those who didn't follow my build, below are the specs:

Bottom End
2005 Ls2 Block (honed .005" over)
Precision Engine Parts forged 4" crank-24x
Precision Engine Parts forged H-beam rods
King Race main&rod bearings
ARP 2000 Rod bolts
ARP main studs
Wiseco -8cc 4.005" pistons
Upgraded tool steel pins
Steel top ring/nappier second (.028/.030 ring gaps for heavy nitrous)
GM Ls2 head gaskets
Powerbond balancer
Turn one power steering pump w/pulley
11.2:1 compression

Valve-train
BTR stroker nitrous cam (251/266 .632"/.596" 112+4)
BTR Platinum .660" springs
BTR titanium retainers
BTR seals/locators/locks
BTR Trunion rockers
Morel 5315 lifters
LS2 trays
Manton 11/32 push rods
GM timing gear/cam sprocket with ARP bolts
New HD GM Timing chain with dampener
Melling oil pump
Improved Racing pickup girdle (awesome product)
NGK -9 plugs

Top End
Advanced Inductions 226cc (243) heads (resurfaced for the swap)

What trans? Is it N/A or do you have a power adder?

Big chunks like that usually come from the thrust, at least from what I've seen, and 90% of those cases are caused trans/converter issues.

edit: nevermind, I see your ring gaps now.

Sorry to hear your having troubles. How big of a shot have you made it up to?

Thanks for the reply. It is a 4L80e trans and I was spraying 300-350 worth of nitrous. However, when the pressure dropped and also when I assume the damage occurred, I was doing back to back WOT pulls NA to tune the car up to 7K. No weird sounds or any issues after the pressure drop.

Thanks bro, really bummed about the damage... I made it up to a .110 pill. The best pass was on a .088 pill and the car went 9.84 @ 139. This was due to not having a working progressive controller at the time. Once I got the progressive working I kept having endless alternator issues and never made a solid nitrous pass.

IIRC main studs require some additional machining to prevent the mains from eating up their own bearings. Something about how the caps don't fasten back down the same. Maybe that's just a BBC thing, can anyone confirm additional things to do for studding LS mains?

Got the call I was dreading from the shop... The block is warped beyond repair at least money wise... Said the thrust bearing had the most damage and melted into the block causing it to warp the main area. They attribute the damage to oil heat just smoking the bearings and I'm really wondering if the standard Melling M295 pump just wasn't up to par...

Crank, pistons, cam and rods are all in great shape and can be reused... Now I'm in need of a new block so if anyone has a source for a Ls2 bare block feel free to share...

I'm running the same oil pump and it's not been a problem. It was recommended from a few different people. If it's the thrust bearing I would be looking into convertor issues.

Thrust Bearing Damage
 

Hi ALL, PLEASE STATE the side of damage to the Thrust Bearing ?

Lance

Damn, that's what I was afraid of. At least the internal parts are ok, which usually doesn't happen. Usually the thrust surface on the crank needs some attention.

"They attribute the damage to oil heat just smoking the bearings and I'm really wondering if the standard Melling M295 pump just wasn't up to par..."

Oil heat?? More like hi converter out psi forcing the crank forward, making brg clearance so tight, the oil film strength was exceeded.
Several threads on this topic. There are ways to control the pressure, that are not expensive.

Dead on here.
Four inch stroke engines make a bunch of torque no matter the brand
A 350 shot of giggle gas is gonna spike the torque more than 400 foot pounds
Torque converters (specially without balloon plates) expand like a heart beating
Aftermarket cranks usually have tight thrust cheeks and require custom bearing
Sanding (bench top sand paper/by hand) to get into that (.007"-.020) range
Plenty of cranks I've seen are in the (.0015-.004) to start. Much too tight

Thanks for the insight guys. Can you just clarify if you mean my converter was ballooning or trans line pressure was the cause... Line pressures are factory in the tune but obviously modified when built internally.

My converter does have a balloon plate but does not have a billet cover... If you could point me in the right direction so I don't go through this again, it would be greatly appreciated! I will be taking the converter to the shop tomorrow go get cut open and have a billet cover installed.

The actual converter BALLOONS from the internal pressure created by the opposite facing fins passing over each other trying to compress the fluid.
I'm betting your torque spike on the hit exceeds 900 foot pounds.
I ruined a pretty decent converter back in the day with a 360 CID gen I as we hosed it with a 350 shot/3600 lbs/3.89 gear/28" tall tire
Car was a bottom ten ride (NMCA Limited Street circa 96') but launched like a shark....LOL G-body shuffle :burn:

I think the proper term is converter charge pressure. Nothing to do with tune setting but more so the amount of power your making. As mentioned when smacking her with a .110 jet when the converter is already stalled to say 3200 and when the kit hits and spikes the rpm to say 4500+ that adds a ton more pressure in the convert in a very short time. The converters do flex a little like a heart pumping and just the fluid pressure itself trying to push the convert off the input shaft puts force on the crank. I've even seen restrictive cooling systems cause higher than normal pressures. Improper finish on the crank thrust surface can do the same damage when higher than normal pressures are on it. There are pressure bypasses that you can put in your cooler lines to try and eliminate that for pretty cheap. Your up there pretty good in power and being nitrous where your smacking her all at once everything in motor and tranny has to be on point.

Thanks a bunch for the insight guys, really appreciate it. The converter was rock solid as in the shot did not blow through it and stalled out to 4K on the trans brake, but again no billet cover which was my fault for reusing it on my stroker motor.... So do you think a fresh converter with anti-balloon plate and billet cover should just about solve this issue?

No. I love would bet you need a way to control convertor charge pressure. It can either be done internally with a restrictor or with a regulator externally.

Not to mention where the converter is "shimmed" to....as far as the depth it engages into the front pump. People usually put one or two flat washers in between the flex plate and converter so as to not pull the converter notches too far out of the transmission pump but as we've seen here; that converter WILL swell a bit even if you get the billet cover as most still use a factory design but enhanced to handle more power.

Don't just go sticking shims in. Never know what you'll need. You HAVE to maesure. I actually had too little of clearance so I had my convertor pads milled like .100" to get the right clearance.

I wonder how many actually even think about that clearance?

I would hope everyone. Clearly goes over it in the paperwork I got with my convertor.