Have to find a replacement block to build up for my Vette. It looks like its down to these two...

Keep in mind everything is a concern here, money, weight, reusable parts, durability...the goal here is to have a running LS7 style engine (which I have many of the parts for already) and I can at least get the LS7 block used at the same price as the LSx.

So, C5, N/A only, which and why?

 

If you are running N/A only then the LS7 would suffice but if you plan on putting any power adders then go with the LSX, price wise you can get the LSX cheaper but have to get it machined. Aluminum LS7 vs the Iron LSX, durability goes to LSX, weight LS7 reusable parts LSX unless you get the LS2 conversion kit then you can go with the LS7. But the LSX is rated for like 2500hp and can be bored to a 454ci I am not sure how big the LS7 can go.

 

there is nothing wrong with an ls7 block at all. i feel the only time an lsx block is better is if you are doing 900+ rwhp, or if you want to do a bigger bore than the ls7 can do.

lightweight (alum) is good for more acceleration. and i dont mean straight line turns, braking etc.

 

I would definitely go with the LS7 for N/A. there's a huge weight difference between the 2 and lighter is faster.

 

I'd just go with a resleeved block. With the LS7 block you are giving up some of the bore versus the LSx. The LSx is way heavier and more expensive, but will support more cubes. A resleeved block shouldn't cost too much more than the LSx once you factor in machine work.

 

The LS7 block will go to 441ci on the stock bore w/ just a little massaging of the pan rails for the rods. It WILL handle more power than most here think, and can be sprayed w/ 300+ at 12:1 comp. w/ good internals. I have a daily 9sec car and use the ls7 block. Lighter is better unless u want more than 1,000fwhp.

 

L92 is an option too, it can be bored and stroked safely to 427 ci. Its aluminum too so its lightweight.

 

go a brand new ls7 block you can buy it at a reasonable price,weight,you have most parts to suit anyway.
personally a resleeved block is not even a option/or asked for.
especially when you guys have easy access to these blocks redaly.
just my 2 cents worth.
cheers dave

 

........and this whole time i thought lsx was just a general term for any ls series engine, not good lol

 

It is. People use the 2 interchangeably so you have to determine if they're talking ls1/2/3/6/7etc or GMPP LSX.

I'm using an ls7 block in my new 1100+rwhp build and don't have any worries. I may throw an F2 and go for 1300rwhp. The GM ls7 engineers said it should have no problems up to 1500hp.

 

I have an LS7 441, FWIW.

 

hahaha they need to make a sticky with all the abbreviations on here

 

Isn't it generally that LSx refers to any number of GM engines (LS1, LS2, LS3, LS6, LS7, LS9) and LSX refers to the aftermarket block?

 

I am using a LS7 block for my TTIX twin turbo Z06 making 946 rwhp. running 9.72 @ 152+. Took it apart and the block is perfect.

Rob.
416 751-8047

 

LSX isn't aftermarket. It a GM Performance Parts block.