r3dh4tch

Why would the block be weaker compared to a 6.0L? In my mind, when I think about the bore centerline on the 6.0L compared to that of the 4.8L/5.3L, I think it has potential to be stronger if left at a relatively stock bore (3.780"). Last time I checked people couldn't bore the 6.0L much without having to worry about having thin cylinder wall thicknesses. I know the 6.0L is tried and true. My brother has one in his truck, and I have wanted to do the same since we did his swap. But since I thought up this build, it looks like it would work just as good as doing a built 6.0L lq4/lq9 (in stock displacement). I'm not looking to build some big cubic inch engine... But for the money, I think it would be worth the effort of trying something different, especially when I know it will work. I don't have any doubts that this engine will be any weaker then a 6.0L... and who knows, it might be something new people start building if it make nice numbers. Worst case scenario, I lose 500-1000 on the block work/pistons, and end up taking the crank/connectings rods and putting them into a lq4 block and buying a new set of pistons and would have a 408. I know these engines are strong, there is a guy running a stock 5.3L at 18psi making over 700 rwhp with a twin turbo setup. The kind of numbers he's making is what I'm looking for, but with a little more reliability from the engine.

PappyDan

iTrader: (4)

what no link to the pistons.

InchUp

iTrader: (2)

Standard
.020
.030
.040
.060
http://shop.enginekits.com/osb/itemdetails.cfm?ID=1299

Those I'd only use as a replacement piston, not so much for boost or nitrous. If you're planning on spinning the 99mm 5.3 motor (bored over from 96mm) to the stock red line then I'd opt for hypereutectic pistons. Any higher RPM limit, forged all the way. Easiest way to know what you're boring the motor to is simple:: 5.3L has a 96mm bore, LS1/6 has a 99mm bore. Bore to the 99mm bore so that way you can leave room for rebuilding the motor some time down the road if you so choose, and to limit cylinder wall flex.

EDIT: by the way I will be watching this thread closely because I too am boring a 5.3 to a 5.7 soon (was supposed to be yesterday but the machine shop never called me back) so this thread peaked my interest. I'll be N/A the whole time, but your build will be nice to follow.

r3dh4tch

I put a link on page 3 to the Mahle catalog for their forged pistons. It's the second to last post. There are no prices in their catalog, so you would have to call them or someone who sells their products.

r3dh4tch

Are you going to have the block sonic checked after you have it bored? If so, could you please provide me with the results afterwards so we ALL know what kind of cylinder wall thickness is left over after doing such a big bore on these blocks? Thanks.

TurboGibbs

iTrader: (6)

From my crude measuring techniques, I've found that a 4.8/5.3 block has plenty of room for a 3.905" bore. And yes the 5.7 is 3.898". The 3.903-3.905 are over bore optioned pistons for the aluminum block and thin steel sleeve.
I can't attest to 20lbs boost but as KBracing96 said, 20 lbs is a lot for gen3/4 engines. Part of the weakness is the 10 head bolts vs 17 of the SBC but as he said the heads flow much better in most cases and boost is measured by a restriction in the intake path and less restriction means more air is getting into the cyl and higher cyl pressures. Basically, a typical SBC with 20lbs boost will have much less cyl pressure than a typical gen3/4 with 20lbs boost. If 20lbs is your goal then I suggest an aftermarket head with a thicker deck surface to prevent distortion and not to worry about a 3.905" 5.3 block.

Here is a 3.905 5.3 block with 4.0 stroke (383 roughly) which I built. He is still working out the bugs and tweaking the fine details with more boost to come.

https://www.performancetrucks.net/fo...d.php?t=414449

SS_bnoon_SS

iTrader: (3)

I've seen full 6.0 long blocks for sale locally for $300-$400 in salvage yards (with melted plastic parts). Even a small electrical fire kills the resale on these things, even though the metal parts are totally uneffected in most cases (though a full on fire will destroy most everything not iron). A friend got one with 100K on it, light fire, and it was still in factory spec on the bore (could still see the factory cross hashes)!!! A fresh hone and rings and he was on his way!!!

old motorhead

iTrader: (10)

I reread the thread. Thought you were one of the guys talking about a big overbore on the 4.8L block. My bad. The block at just a .04 overbore ought to be plenty strong. My son has a 5.3L block bored to accept LS1 standard bore forged pistons. He's running about 7psi on a trick turbo system with LS6 cam. Strong set up and has been running flawlessly for several thousand miles. Rear end hasn't fared too well though.

How many cubes are you giving up going with an overbore on a 4.8L block vs a slight overbore on a 6.0L block? I'm assuming use of the same stroker crank. The same or more power can be had with less boost with the bigger engine. Less boost = more reliable in my book. If you do come across a rebuildable 6.0L, it comes with better heads also.

Reckless

iTrader: (7)

The first boost engine I built back in 1999 was a 5.3 block .120 over and it held up to 15lbs with no issue. I sold it when I moved to Ohio, and I think someone else ended up with it later on. So it went through 3 folks with no issues at all. It was a stock crank setup with Lunati rods and Ross dished pistons.

What suck out here in Hawaii is the total lack of available engine cores locally

r3dh4tch

I'm glad someone finally chimed in that has some great info. I like the numbers from the link you provided me. That's about what I would like my truck to run when it's said and done. BTW, what cylinder heads are on that engine? I was planning on running some 317s to help lower compression and I knew that they flow better then the stock 4.8/5.3 heads on the older engines. This information satisfies me now... More cubes is always good, and if I can run less boost and achieve the numbers I want, then I will be very happy. I think I'm going to consider this 3.905" bore with a 4" stroke.