How many here has bored a 4.8/5.3 block to 0.120 to achieve the 3.898 bore size of the 5.7?

 

Not sure how many on TGO have done it, but it's been done a lot on ls1tech. Most aftermarket engine suppliers use these blocks as the foundation for their 383 mills. (ATK, Texas Speed, etc)

 

You can bore out a 5.3 an eighth of an inch? I can't imagine there's much of the cylinder wall left.

 

Yup, they put thick liners in the aluminum blocks and there is tons of meat in the iron ones. It ends up being .118 overbore. Texas Speed offers a re sleeved 5.3 up to 4.125 in bore. It's a versatile block.

 

Things that make you go Hmm. I have a couple of LM7 5.3s. I also have (or will have soon) a set of LS7 heads from an LSX 454. Might be an interesting assembly.

 

The texas speed re sleeved 5.3 block is also stronger than an LS7 block. It's also only $2k. This only works on aluminum 5.3's. Your stuck with a 3.898 max bore on an LM7.

 

No adders, some AX and open track day stuff and regular driving so with what has been said I think I'm good.

I have a actual 5.7 block I intend to use but if it has the cracks on the thrust sides I'll use the 4.8/5.3 block I have.

 

Figures. The LS7 heads, from what understand, have to be used with a large bore. Less than 4" won't cut it.

 

Yes. Minimum 4.125.

 

Won't fit on a normal LS engine, bud. You'll need to go big bore (4.125" or more) to use those heads. $$$$$

From my LS7 head research a couple years ago, I think those LSX heads are already ported use the Lingenfelter CNC program. It's not a factory LS7 head. Good stuff right there.

 

These are the heads in question. Still on the crate engine as purchased from GM but there's some Texas Speed stuff soon to take their place. The heads should be coming my way should I decide to make the move for them.





Thanks for the loan of the QUICKCHICKEN. And good luck with your project.

 

Oh wow, I thought those heads were CNC ported. I guess not?

 

Might be the "R" version that gets the full Monte. I'll have to check that out.

 

I cruised the Chevrolet website and sure enough the LSX454 head is literally "as cast" and not CNC ported. There are CNC ported heads available (which I believe use the Lingenfelter CNC program), but the crate engine didn't come that way.

 

The LSX454R was discontinued although the specs are here:
https://www.gmpartsdirect.com/oem-pa...ngine-19260835

The R version used a CNC'd port and chamber although I can't say if it was a Lingenfelter program.

 

Wow, that LSX-DR is so much different! It has a tiny 50cc combustion chamber with a massive 313 cc intake port volume. Definitely nothing in common with the factory LS7 head.

 

This is really starting to explain though why the LSX454 is such a turd. It literally has stock heads and stock LS7 intake!

A 427 LS7 will gain +200 Hp with a H/C/I package. I'd think the LSX454 is begging for a H/C/I package to light the wick too.

 

Lookie what I found... 680 Hp from what I'm guessing is a ported AFR LS3 head that fits medium bore engines.

https://ls1tech.com/forums/dynamometer-results-comparisons/1891043-427-small-bore-engine-w-mms-260-ls3-heads.html

Did you notice how similar that engine is to the one I have for sale? I think I just found the recipe to make that engine scream.