1 of my supply house salesmen is giving me a 5.3 that he broke a rod on. according to his mechanic the blocks fine but he managed to break the timing cover when pulling the block. anyways i pick it up on monday and like i said i'll have exactly $0(well maybe $5 in gas) when i unload it in my garage. motor is from an 03 with 280,xxx miles. a local dude is offering me a 5.7 rotating assembly fairly cheap($250) but from what i can tell after looking around online the cranks are the same, the rods are either the same or the 5.7's are .025 longer(i've seen people say 5.7 rods are either 6.1" or 6.125" long and everything i've read say the 5.3 are 6.1")

so the only difference i can see is the piston. am i correct in this? i read somewhere awhile back that 5.3 can't be bored out that big but i've read of a few guys here that have done it so is it certain blocks that can't or did i read something wrong? i've also read the 5.7 cranks are balanced differently then the 5.3. does this cause any issues? i was going to do a 6.0 but i've had some **** luck the last couple months and now i just need a running motor and depending on bore to piston clearance all i'll really be into this motor is a couple hundred bucks....$500 max if i have to buy new pistons and bore the block. i won't know exactly what's going on till monday afternoon but i'm trying to plan ahead

 

What are your goals for this? Just to get a running engine as cheap as possible? The big boys use the 5.3 and put sleeves in it to make 400+ci, but thats not the cheapest route... "iron ls1s" are fairly common using an ls1 rotation assembly in a bored 5.3 block.

 

right now my plans are just getting a running motor in the truck as cheap as i can. later on when moneys better i'll either swap in a 6.0 or add goodies to this. if the pistol to bore clearance isn't within spec i'll have to buy pistons and bore the block anyways so would the 5.7 assembly be more beneficial then just getting some .010 or .020 stock oversized. looks like i'll be paying about the same. in a perfect world all i'd have to do is gaskets, bearings, and rings plus the 1 rod but i never seem to find that perfect world

out of curiousity what is the biggest you can bore a 5.3 out to without sleeving

 

hell i still need to either find an 80 for cheap or rebuild this 60 for the 6th time

 

so i picked up the motor today and it turns out it's a lq4. wonder what caused the rod to break where it did...about an inch from the big end. what kind of hp are stock lq4 rods designed for? thinking about doing a forged bottom end for a future turbo i just need to figure out my budget for this build. thinking 450 to 500 hp n/a and don't know where i want to be when i go turbo.

 

btw this will be my dd so if those numbers aren't reasonable and still keep decent highway mileage then i'll tone it down abit. i'd also like more torque down low for when i have to tow something. i really don't want it to be like my '03 3/4 ton 4x4 that got 11.72 mpg. 16 on the highway would be acceptable but 20 would be awesome

 

I dont know if you will get 20 out of a 6.0. I have a LQ4 in my 1/2 ton and my aero force is showing avg mileage of 18.3. Doubt thats right though. Im thinking more like 16.