A_VAS

iTrader: (16)

basically this is first time I'm tearing into one...and the thrust bearing being only the upper shell...has me wondering.

engine I'm building will get loaded hard...twin turbo deal. 900+rwhp

any of you guys playing in this realm with the gen V blocks doing anything differently with the main bearings?
The offset of the center cap, won't allow running the standard upper/lower shell thrust bearing, but I could rectify that in the machine shop, just not sure it is justified and/or worth the hassle.

Thanks

djhenderlong

I don't think your going to have an issue with just running the upper shell. A lot of OEM switched to just using half a thrust bearing.
Is the LT4 the same way?

A_VAS

iTrader: (16)

I believe the LT4 is, but I haven't seen one torn down.
The GM bearing p/n is the same I think.

even if the LT4 is using it, this is being pushed way beyond that power level....I guess is why I'm questioning it a bit.

Bob@BruteSpeed

iTrader: (16)

http://shop.brutespeed.com/GM-Corvet...1-Complete.htm

Here's one where the thrust bearing got torn up. I bought it and decided to go LS in my Vega. I know at least one place is machining them for a full thrust bearing. Bob

A_VAS

iTrader: (16)

thanks for the pics Bob

Dang, didn't see that or I would of bought it to use for this build...good deal for $2500 complete.

So that pic, looks to me like the 1/2 thrust wasn't the root cause, the crank didn't tear up the actual thrust load surface of the bearing (the flange).

To machine the block to use a upper/lower shell, the cap needs to be relocated so the parting surfaces line up with the block main web. I'm not sure what I will get into doing that...since the side bolts then might not line up. Wonder if the shops doing them use a center main cap from a gen IV or something. Any insight or contact info on that I'd appreciate if you can share.

Bob@BruteSpeed

iTrader: (16)

You're welcome. You're right, it doesn't appear the thrust loading surface was damaged. The thrust bearing though, is the only bearing that got damaged. Check out what Texas Speed states "All TSP gen 5 LT1 engines will come standard with an ARP main stud kit. GM has had problems with the main caps moving in the gen 5 LT1 block, so we require all of our gen 5 LT1 engines to get the ARP main stud kit to help alleviate any possible issues with this."

I believe the shops that are using a 360 degree thrust bearing are machining the LT's main cap for the bearing. If I come across who is doing it I'll let you know. Bob

A_VAS

iTrader: (16)

Thanks, yes I'm using the ARP studs here.

The #3 main cap on the Gen V block is already got the circular cut so a flange bearing does fit on it.
however the fore/aft alignment of that cap is way of, when you put the 2 shells in they have a misalignment of like .050-080"
so I'm thinking the cap either needs to be shifted/doweled to new location, or you start with an uncut cap, install it, then machine flush to the thrust surface of the block. Hard to describe
Thanks

82cetuner

iTrader: (9)

when i was in gm school and lt1 first came out we tore one open that had failed and found the thurst bearing was destroyed, we pretty much knew that going into it cause crank runout was about a quarter inch of play. the failure however was due to the bearing had a slight taper in it which caused it to be eaten up by the crank and eventually it ate down enouph that the thrust off too.