Grimes

iTrader: (3)

I think this shows what was was mentioned in earlier posts. These are production blocks that are not meant to be bored out. I bet they pass the QC at the plant for a stock application. Obviously this sucks if you want to go larger. Glad you posted pics though klymaxr. Thanks.

SSZ

Yep, that block looks a little F'ed up. I would not expect something like that from GMPP. But it happens now and then. You gotta wonder how that doesnt get rejected. HMMM. Someone not doing their job i guess

WKMCD

iTrader: (2)

THe unknown is one reason I just went ahead with an LS2 block for the 402..There are a ton of them out there without problems.

This is really disappointing.

Rock_Daddy

iTrader: (8)

Your acting like they are all like that. Granted that was a horible track record for a start but I dont think they will all be that way. I havent heard of any others exect fo rthis streak having such issues.

corvettetimmy

I recently had an ls2 block resleeved, and 2 of the sleeves were shifted a significant ammount. I was fortunate that then new sleeves were of large enough diameter to compensate. I dont believe that it would have ever caused any problems if i wasnt re-sleeving it, but it almost caused problems during the re-sleeving process.

96 Comp T/A

iTrader: (8)

Well, all things being equal you would want to have equal sleeve thickness all the way around for uniform heat dissipation, (and by extension uniform bore distortion) in a perfect world. In the real world you are going to have thermal gradients throughout the casting due to siamesed bores, coolant flow characterisctics, and intake and exhaust flow patterns. It has been my experience that I prefer the thickest sleeve you can get, because it provides a stable cylinder wall for improved ring seal and it is an insulater, keeping more of the energy created during combustion in the chamber and cylinder. Almost as important is the material used in the sleeve. I don't have any practical experience with the Darton brand sleeves (yet) but some of the bores that I have sleeved previously (using LA Sleeve products) exhibited wear and sealing characteristics that were much more favorable than OE cast iron. I would assume that you would also see favorable results from Darton.

I am also vaguely aware of several ultra high end sleeving technologies, meant for F1 and top of the heap Cup teams that utilize ultra thin sleeves made of an undisclosed material. No one (that I know of anyway) will say much about it, but something may turn up at PRI in a couple of weeks.

Steve - Race Eng

iTrader: (1)

I agree, thicker walls are better. Ductile iron has almost four times the tensile strength of the aluminum casting 110,000 psi minimum tensile Darton ductile iron vs 30,000 psi tensile of 319 T6 aluminum used in the LS castings and three times the strength of the cast in gray iron liner. It is better to rely on the sleeve thickness than to install a thin wall sleeve and rely on the surrounding aluminum for strength.

Darton makes most of the dry liners used by the Top Fuel and Funny car teams. Darton also makes ductile dry liners for several cup teams and top running Pro Stock teams by the way. I know who they are but can't mention the teams. We will shortly be working on an MID sleeve for one of the teams. The high end liners you were talking about are made by Perfect Bore. They are nikasil coated thin wall steel. Light weight and very expensive.

When I speced the dry liners for the LS2 blocks, I was well aware of the offset sleeve issues in this post when doing the R&D on the first blocks. I had Darton make the replacement dry liners large enough in outside diameter to ensure the blocks would fully clean up (old liners would be completely removed) during the machining process, so that the new liners could be installed directly over the crank axis and on 4.400" bore centers where they belong. The sleeve wall thickness is therefore sufficient to allow boring the new sleeves much larger than the originally installed sleeves with equal wall thickness all the way around.

I don't know how the iron liners are held in place in the sand molds during casting. Apparently some are shifting position when the aluminum is poured into the mold. This casting technique is by no means easy to do so don't fault GM for some problems. But I don't see this problem to this extent in other manufacturers blocks using cast in place liners, Honda, Nissan, Subaru, that I routinely resleeve. Note that Ford and Chrysler use press in liners in their blocks perhaps because of the technical issues of keeping the liners in place during casting.

I like GM products by the way. I own a C5 Z06 and am waiting on the new trucks to be released.

Steve

1BADWS6@STENOD

iTrader: (6)

klymaxr-

What cylinders are the ones with the thinner sleves? I just went and looked at my L92 block sitting in the shop and cylinders 7 and 8 are thinner than the rest...but just on the side closest to cylinders 5 and 6. Have you found anything out about this problem? Would like to know if this is something to worry about before it goes out to the machine shop!

klymaxr

Thanks for the reassurance guy's, you may also find that when you look from the bottom up they are also in crooked! so in fact the sleeve may very well be even THINNER at the bottom then at the top, as i stated this was the last block, there were even bigger differences, The outside dimmention of the visable sleeve top is just under 4.280, with an inside dimention of 4.065 as delivered then a pro cleanup hone with a torque plate of .015 giving a final bore size of 4.080 this leaves a visable sleeve (if perfectly bored in the centre) thickness of .100/2.5mm, now to think the dimmension of a LS-2 block are @4.280 with an inner bore of 4.000 with a max tollerable over bore of .030 giving a GM min tolerable wall thickness of .125/3.125mm. So why,if the ls-2 is maxed out at 4.030, does the same sleeve come 4.065 in the L92, why did they not just do a larger outer diamiter sleeve and then allow for the casting flaws...although i'm still not in favor or condoning the non centered sleeves, just that it would only make sence and there would be insurance that the walls would still be thick enough if off casting exists.
max
PS> thanks for all the poss input and I agree..i hope someone forwards this to another gm brass before the persons responsible sweep it under the CARpet.

Shinobi'sZ

You know I had a very reputable race engine shop build my short block for me and when they called and told me they had to deck the block because one of the cylinder liners/sleeves (stock LS6 block) was down in the block .003". They ended up decking my block .004"...which changed my deck height a little bit....but I pushed 1000 bhp with ease. Unfortunately I used the stock bearings. and have since notice a decrease in oil pressure.

I really have to agree that the stock LSx block were never engineered to be full out racing blocks with critical eye for detail..they are all assembly line parts...even if they get hand assemble they are not using "custom" made parts...the parts come out of a bulk factory too...doesn't mean you can't make a lot of power with one of them....maybe it will start to make some sense for some when they see the price tag on a C5R block, Warhawk, or other Billet Spec block. There is a reason they cost a lot of money.

klymaxr

Apparently..just got word from dealership parts mgr that the shipping warhouse has pulled all blocks off the floor and the line...which line? ..i dont know. Looks like i may be waiting for a while for a good block to be seen. I'm trying to find out whether, if i build this last block and a cylinder splits, will gm cover a new block? They have also already had to order a new complete l-92 engine for a customer in service due to a catastrophic failure on a 2007 truck.

Bring the Noise

Which truck as the L92 is currently offered in only 2 vehicles.

LSs1Power

iTrader: (5)

I know that Erick who used to work at EPP as an engine builder didnt like the LS2 blocks for the same reason. That is one of the main reasons i went with a LQ9 block for my FI build up. It would be interesting to see people with LS2 blocks post pictures of their blocks.

Rock_Daddy

iTrader: (8)

I just talked to someone that works as an Eng in what I think is the only engine assembly plant for these motors in the US and they wern't aware of any issues or parts being [ulled and definitly nothing pulled from the line. They have been running, business as usual every day since this thread started.

Just info Im passing along.

SideStep