2xLS1

iTrader: (25)

I posted this on LS1tech and didn't get much feedback so I'll try it here.

Boring a 5.3L cast iron block to 4.00". Who has done it and did it last?

I'm not asking if it can be done or should be done. I know a machine shop that did one and didn't sonic test the cylinder walls. I'm more curious if anyone else has done one and did it last. And if it didn't last, what gave out. This was not a performance build, but a stock build for a daily driver truck. They used dished LQ4 pistons and LS1 241 heads and a stock LQ4 cam.

1FastBrick

iTrader: (17)

A regular Iron 4.8/5.3 Block will not go 4.00. most likely it will break through the cylinder wall.

If you find an early 4.8/5.3 block that also has a 6.0 mark on it it will go 4.00

2xLS1

iTrader: (25)

Thanks. You replied to my thread about this on LS1tech. Like I said this is assembled and running in the truck. It was not a 6.0 marked block. They did not bust through the walls boring it. They said they measured a thickness through an opening in the front of the block to the cylinder wall and it was close to what a 6.0L block measured. That's all the cylinder wall testing they did before assembling it. I've never heard of it being done before this one. I was asked to tweak the tune for the added CID. I'm curious if anyone else has done this and their results.

1FastBrick

iTrader: (17)

With out Sonic testing I wouldn't attempt it. I have seen and heard of some blocks busting through at standard LS1 bore size.

It's all dependent on the core shift in the block and the wall thickness.

The only way to know for sure would be to sonic check it.

If you look at 1 of these blocks down the water jacket, after about 1/4 - 3/8 of the way down from the deck, the bore tappers inward and is reduced in diameter.

Did they keep any records? I would like to know what Block casting number did they use?


Maybe one block is better then the rest. The early blocks are pretty rare but I know they are capable of going to a 4.00 bore.

2xLS1

iTrader: (25)

I think it may have been the original 5.3L block that was in the 03 truck. Next time I'm there I will ask them.

1FastBrick

iTrader: (17)

I realise my post may have come across as combative and that its not what I was intentionally trying to do.

I did some more research but there is little to no known info on people going that far. In post #9 of this thread, a guy claims to have done a few. Post#9--->max bore on 5.3? - LS1TECH

Post#3--->4.8 5.3 max bore - LS1TECH

Pots #50--->5.3 to 5.7 - Page 3 - LS1TECH

Maybe try contacting some of these guys?

I would be real curious on your findings as there is not much info out there.


The guys that go to 3.898 or 3.905 seem to have no problems and some even use forced induction. I did see a guy bore one and it broke through when they went 3.898 so maybe it was a bad casting or the cooling system was not properly maintained.

blown02408

iTrader: (4)

I tried going to a 4" bore on my 02 5.3l block after the number 7 piston blew and gouged the cylinder wall, the walls ended up way to thin.

slowrcsb

we have bored a few 5.3s to 5.7s with no problems making 900 plus hp not sure on exact bore size tho

Suburbazine

That's a 3.898 bore. Mine was also bored to 3.898 and there was apparently room to spare on a 02 5.3.

Mang213

iTrader: (1)

+1 that's the max bore you can go to on a 4.8/5.3 block. Make an iron LS1 and roll. Later blocks are even more forgiving of an overbore