mnug13

I went to pick up a 5.3 block yesterday and to my surprise when I got there it was an almost complete short block. However after looking at it the reason it was almost complete was because it snapped a connecting rod so one of the pistons was MIA. On the bright side the crank looks reusable and the block still looks to be in good shape aside from a little scoring in one of the cylinder walls. With it needing bored would it be possible to run LS1 internals? I want to use pretty much stock pistons to keep compression lowish in hopes of putting a turbo on it eventually. I guess this will pretty much be a slow build thread with lots of questions since like I said this will be a crash course for me with a Gen III block.

KCS

iTrader: (20)

Yes, people bore 5.3's out for LS1 pistons all the time, it's just not very cost effective when you consider the costs for machining.

mnug13

I was just mkaing sure it could be done. I know it's not too cost effective but I've already got the block and can't find too many decent 5.7 or 6.0L blocks around here so I figured why not. Would it be better to use 5.3 factory heads with new springs and some machining done to them or buy a set of LS1 heads? I've heard that the 5.3 ones flow better but I'm not sure.

Snkebait95

iTrader: (16)

They flow about the same, the intake valve is 1.89 instead of 2", and the combustion chamber is smaller

kossuth

iTrader: (12)

Before you ever put a single dollar into machining or purchasing parts have the block sonic checked for thickness. Some blocks have core shift and can't be bored to a 5.7 This isn't one of those things you question. You have got to do this. Better to spend some cash and know you have enough material vs going to thin and blowing it up.

RezinTexas

for the cost of boring/honing the 5.3 block you can probably find a 6.0 bare block.

KCS

iTrader: (20)

I would go with the 241/853 LS1 heads since you said you're wanting to keep the compression down.

bww3588

iTrader: (49)

Or 317's. If it's opened up to 5.7, 10:1 would be a bit high depending on the amount of boost.

bww3588

iTrader: (49)

Excellent point. Going .119 over on a 5.3 will not be cheap. You can find a 6.0 block and have it gone over, machined and stuffed and probably come out very close in price to have the same done to a 5.3 opened up to 5.7

mnug13

I'd definitely have it sonic checked first. The only problem with going to a 6.0 is I can't find many for a decent price around here. Or at least haven't yet. Do they make an oversized piston for a 5.3 or is an ls1 piston my most likely option? A turbo is kind of a way down the road dream. It'll just be a mild street engine for now. I can get a set of 5.3 heads a fairly good price with a little machining would they be a good option for now? I'm full of questions today. Only two more for now though. I was checking out my block even further today and realized the bottoms of two of my cylinders got chewed up from the rod snapping and I was wondering how much of a problem that would pose if any? Finally shouldn't there be another transmission bolt hole across from the one on the right like on old school blocks? I did the best I could at getting some pictures for these last two questions.

kossuth

iTrader: (12)

They do make a 5.3 oversize piston which will take you to 3.790, 3.800, and I believe 3.810 off the shelf. Those from what I've seen are hypereutetic pistons and not forged. If you are looking for forged slugs your best bet is going to the 5.7 bore. Wiesco makes forged slugs for the 5.3 but they are the only ones that I know of.

1FastBrick

iTrader: (16)

As far as the damage, the block should be pressure checked and magnfluxed. The damage should be ok, but if either one of those test reveal a leak then it's probably junk.

There is no transmission bolt hole on the right rear of the LS engines because the cylinder wall is to close.

Hyper eutectic replacement pistons are available in std, .020, .030, .040

Wiseco also makes Forged pistons for the 5.3L bore in 3.780 and 3.800