What is the difference between a LS7 and a LSA block? Is one stronger then the other?

 

Other than displacement?

 

Yeah, LSA is stronger. Better casting and more cylinder wall thickness.

 

Don't forget the LSA piston squirters!

 

GNX7's post shows in the list, but not here?
Edit- showed up once this was posted.... weird....

 

I had same experience. Tried to view GNX7s post
Last night and this morning, unable to view till now.

 

As well as ductile iron main caps.

 

Cost is about the same between them, so if you're looking for a boosted motor, the LSA is a much better starting point.

However, if you're looking for a lot of boost, the LSX or even something like the Dart SHP 2 would be a better block (and the Dart in iron is cheaper than all of them and uses piston oil squirters, 6-bolt heads, and splayed 4-bolt billet main caps) - it's essentially a hybrid Small Block Chevy on the bottom that uses the LS pan and LS top end.

 

I'm gonna do a LSA block in my build once I get a buyer for my LS3 block.

 

Bore size too is an important difference if it won't be sleeved. Ls7 is 4.125 bore. LSA is smaller bore, which is where a lot of the strength comes from. This may effect head choices if you were planning on a large bore head.

 

Thanks for all the answers. Trying to decided which direction to go for my build.
Looking to build a 454 cu LS using a sleeved block, no spray, naturally aspirated 12+ compression on E85, with Brodix heads, tight lash roller and a MSD intake. Trying to get 625-650+ rwhp in a stick car keeping the rev around 7000rpm. How do these blocks hold up? Material wise, are these block all the same once you sleeve them? When push them to the edge, will they start to leak being that they are aluminum cores?
My local very reputable shop prefer to use the iron block for something like this but my 05 GTO is a pig already, with a iron block, it will be in SUV weight trim. This will be a weekend street cruise car. Not a daily driver and also want to keep everything under my stock hood.

 

Steve @ RED, who posted earlier, is the guy you want to speak with.

Power adder guys seem to prefer the aluminum 5.3L blocks because they don't have the bay windows below the cylinders and that's supposed to keep things more rigid. However, those bay windows can be worth a considerable amount of power in a big displacement combo like what you plan. If a block doesn't have the bay windows, you can have a hole drilled through the block under the main saddles like the early Gen III blocks, but the bay windows are still the better option.

The LSA block has a better material, but it's not needed for an NA combo like yours IMO. If it were me, I'd grab the cheapest block I could find with the bay windows. An LS7 block with a cracked sleeve would probably be the most common, but an LS3 would work too if the price is right.