sprayjunkie

Im starting to feel like maybe someone should start a new thread to debate this topic. Does anyone have any more info regarding the strength of these blocks in relation to each other?
Thanks

Bill Reid

iTrader: (14)

Have you researched all the machinests available that offer such a service? If you have an LS2 block already or can find a good used core... then the cost of resleeving is VERY competitive as compared to the cost of an LS7 block outright... even with its new price. If you have to purchase a new LS2 block... then yes I could see your point.
There are some attributes of the LS7 block that appear to have been engineered for more strength. The caps themselves along with the dowling (and no interference fit on the side of the block, only at the web) show GM has been concentrating on improvement in that area. Trying to replicate the improvements made on the LS7 in the mains area on an LS2 would most definitely add to the cost. How much? Ask a machinest(s) that offers the services. Regarding cast in sleeves versus pressed in sleeves and the strengths and weaknesses for both you will not find real engineering empircal data here on this forum to prove the LS7 pressed in sleeve is stronger or weaker than the LS2 or L92 cast in sleeve. Don't expect a GM drivetrain engineer responsible for engine block devleopment to chime in with the REAL reasons why they make the decisions they do. Machinests will have there own opinions regarding what they see coming out of GM (materials used, machining processes, etc) and I do value what they have to say. What I am suggesting is to get your info from more than one source. In the end you will use a reputable machinest anyway to assemble your motor, right? Discuss what you hear and information you come up with yourself with the person who will ultimately assemble your motor. Chances are you will have made a great decision... one you can live with.

Bill

sprayjunkie

Thank you very much for an informative response, Bill. We are going from an LS1 setup so we do not have a block to start with. We will be most likely ordering a complete shortblock from one of the many vendors offering such motors on this forum. As most of the assemblies out there seem to use similar, if not the same rotating assemblies, the last decision to make is which block to stuff it all in. I brought this question here to LS1tech because I figured I could get alot more info than making 10 different phone calls/emails. As most of the suppliers here offer both the L92 and LS7 based motors, its tough to get them to recommend anything besides the costlier option, if you know what I mean.
So far it is looking like the LS7 block is winning the battle....
Billet mains+N20= piece of mind!

JakeFusion

iTrader: (7)

My initial post was more about the liners and the fact that there's simply less material around the LS7 cylinders. I am of course using the assumption that for all intents and purposes, that they are the same block with the same density and strength of alloy, which common sense would tell me that the LS7 would then be weaker or at least only as strong as the LS2 (billet mains and new designs apparently incorporated). Since I do not have access to every block in existense, I can only go by internet hearsay, though, I do base my judgements off of those of people whom I consider to be the best in their field as a basis from which to form my opinion. Unless somewhere it's stated by GM that the LS7 aluminum is a different grade aluminum that's stronger, I may stick by this. However, I'm not above changing my opinion on this, Bill. I am not claiming to be an expert.

I'd still run an Iron Block 408 with billet main caps if strength were a concern but displacement or weight wasn't, or wait for the new GMPP Iron Block. Why? Well, I do know from personal experience that bores become out of round with aluminum engines when subjected to huge shots of nitrous. Iron engines hold their shape far better. This doesn't make an aluminum block shitty, it just means that it requires more maintenance and more money in a rebuild.

Bill Reid

iTrader: (14)

Well said... and although I may not agree with you in some aspects I do repsect your opinion. At the end of the day there are alot of assumptions and opinions. Everyone has them. It is the consumers responsibility to sift through all them before unloading that hard earn cash. Doing so can only add confidence in the decision made

Absolutely I agree that adding iron to the equation, assuming no worries on weight gain, is most certainly desirable... my opinion too ... the LSX will be $2+ large. A junkyard iron 6L case would be the absolute cheapest approach to a bullet proof bottom end, again with weight not being a concern. Add dowled billet caps and 1/2" head studs and that will just about handle anything that is thrown at it.

sprayjunkie, maybe add to your questions to your machinest the cost of fixing up a junkyard block and then weigh the cost against your other options.

Bill

sprayjunkie

Unfortunately an iron block is out of the question as this motor is destined for a C5 daily driver Vette, and the owner is very concerned with maintaining that cars excellent balance and handling capabilities, while being able to stomp 'busas from a healthy roll...

Keep the invaluable tech coming guys!

firefighter

Not that I'm anybody but my deduction from everything I've read is that if you are starting from a new block go LS7 (assuming you wan't bore size) if you are working with something you have an LS2 resleeved is a good option. It seems to be the general concensus that the Darton sleeves are stronger but to take a new block and right out of the box resleeve it is a little crazy just go with a C5R or the new LSx block or if you got money a Warhawk. I would imagine that for a N/A 700fwhp motor the LS7 would be just fine if you want to throw alot of boost or Spray at it then go with one of the more exspensive options.

If I build a scratch motor I'm gonna go LS7 if I work from a pull out I'll go LS2 and stroke it. It really depends on the budget I set for myself.

99sprayjunkie

Anyone else?
I know someone has got some more first hand experience with these blocks....
Lets hear it!

Ryne @ CMS

iTrader: (10)

i have a 418 stroker l92 block in my gto, the block looks just like a ls2 block, but with larger bores.

99sprayjunkie

Well, after finding a set of aftermarket billet mains for a good price, it looks as though we will be doing an L92 based setup. The cast liners seem to be the favorites and the mains were keeping the LS7 out front till we found these.
Should kick some serious *** with the CNC'ed L92's up top and a wild cam.....can't wait to see some results from some of the other combos going together out there.