Rebuilding A 5.3

Chestah · December 3, 2007

My truck is very close to racking up 100k and I am considering a performance rebuild of my current engine. There seems to be tons of information on pre-99 350's, 454's, etc, but not much on Gen III Small blocks. What exactly would I need to rebuild? I would definitely want a bigger cam and a higher stall to go along with it.

Someone tell me what you think?

Schmids5.3l · December 3, 2007

This is what I'd do....and am going to do when this bad boy racks up that many miles.

Stock 5.3 bore is 96 mm, I'd bore it out to 99 mm, aka a stock 5.7l LS1 bore which is 3.898" (or 3.902", I've heard both a lot). That way you can toss in any stock sized LS1 pistons, which I strongly imagine can be found easily and cheap, forged too. The 5.3 and the 5.7 LS1 LS6 have the same stoke, so with that bore you'll basically have a LS1 with a truck intake and heads. I'd also get some forged 6.125" stock sized connecting rods. If you don't mind spending an extra $5 at the pump when filling up, you can run 93 octane and have the heads milled to achieve 10.5 - 11:1 compression. It's cheap too, no more than $100 bucks. Aluminum heads warp over time and might need them milled anyways. If you mill your current stock 862 or 706 heads .050 you'll gain 1 full point of compression, which takes you from stock 9.5:1 compression to 10.5:1 compression. Good for 20~ hp.

The 5.3 block WILL handle that bore size with ease, there are guys boosting 5.3's bored to 5.7 and their strong and reliable set ups. But, for this entire build, TUNING IS KEY!!!! That set up would be a strong motor and excellent for daily driving depending on the cam you choose.

Don't bother with a new crank or a forged crank, these crank shafts can handle 1000+ hp.

For that set up I'd recommend Thunder Racings 220 duration .551 lift @ 112 or 114 LSA cam with a 3000 stall. That cam and stall alone on your truck would kill a second on your 1/4 ET's when tuned. I'd say with the rebuilt motor and cam you could hit mid 13's easily. The motor would be a brick s**t house too, with forged pistons and rods you could spray the hell out of it with a good tune. But I can't stress how important it is to have a spot on tune, especially when spraying. If the TR220 isn't big enough research other cams on those sites, or look up Patrick G on LS1 tech or google, for $25 he'll spec you a dream cam for your set up.

I'd register on performancetrucks.net and search the hell out of it, there's tons of gear heads on there, most make me look like I know nothing about these engines I'm on there, my sig isn't on there tho because someone complained they could get in trouble at work because of it....IMO they should be working at work, and not looking at my sig and bitching to the site administrators because of it... But anyways GEN III motors have ridiculous amounts of info on them. performancetrucks.net and LS1tech are some websites full of LS wisdom. But take everything you read on the internet with a large disclaimer, anyone can post anything on the internet. For reality, I'd call speed shops, dyno tuners, machine shops ect. with your plans.

Zembonez · December 3, 2007

WELL...

I do believe you woke up Sam with that post! Darn good information there.

While the subject is still alive, what is the difference in the 4.8 and 5.3? Is it just a bore difference? I'd like to build a 4.8.

Schmids5.3l · December 3, 2007

WELL...

I do believe you woke up Sam with that post! Darn good information there.

While the subject is still alive, what is the difference in the 4.8 and 5.3? Is it just a bore difference? I'd like to build a 4.8.

Different stroke, same bore. If you bore out the 4.8 to 3.989 you would get a 5.2 or something!

Draenor · December 3, 2007

WELL...

I do believe you woke up Sam with that post! Darn good information there.

While the subject is still alive, what is the difference in the 4.8 and 5.3? Is it just a bore difference? I'd like to build a 4.8.

Stroke.

The 4.8 has 83mm the 5.3, 92mm

Zembonez · December 3, 2007

AH... so the crank/rods would be the difference between the 5.3 and the 4.8.

Didn't mean to hijack the thread... just got me wondering with all the 5.3 info.

willysts · December 4, 2007

I just bought my '03 Siverado 5.3 with 169,000 miles on it, and it actually runs great by the way, but if I pull that engine out for ANY reason, it's getting a crate motor...a 5.7 LS6, or a 6.0 LQ9 or perhaps even a 402...all depends on my pocket book at the time.

Can't do it now,though!

AirForceAngler · December 6, 2007

I have my old 5.3 sitting on the engine stand with 116K on it and full of sludge still from using coolant for so long. This thread caught my attention for something to due with rebuilding it for the future. Another good site to check out is LS1truck.com.