Which 5.3L's are best?
 

I just picked up a 98 Z28 and it's about to eject a rod. Going the Gen III 5.3L route, but I am seeing minor differences on the interchange list. Any specific year better than the others? Also, this engine has a cam in it, but the previous owner doesn't have a clue what the specs are, any way of finding out?

Last question, this engine allegedly has a tune on it, but I don't know if it's specifically tuned for this cam. In the event that it is and I don't swap the cam to the new motor, will the new motor run, or will I have to tune it back to the stock specs?

A L33 would probably be the best.

Great question bro. I just picked up a block from a fellow racer. It's a 09 model aluminum bblock bought for 250 bucks. Pay attention to the casting number on the front face of the block. Some of these 5.3 blocks are resleevable which means it can be turned into a 454 Ci monster. The casting I been told is best is 12571048. I didn't tell my buddies that when I went to look at the 5.3 I bought from him tho cause if I would had told him those motors can be turned into big cube motors I would had never got my hands on her. Sometimes you got to lie to get what you want LOL

Define "best", some folks are fixated on highest performance stock but sounds to me like you want easiest fitment into the car.

For most direct fit you are going to want to stay close in year.

Far as tune, going to have to retune.

I know that everything is going to have to swap over anyway. Manifolds, Intake, accessories, motor mounts, and sensors since it's on the weird 98 computer. I care somewhat about performance, but I care more about reliability or year specific quirks.

Will a LS7 intake work on my 5.3? Is it worth the change for improvement?

That has nothing to do with this thread and is a stupid question. Spend some time learning the basics different LS engine's architecture, and save the newbie questions for the newbie section or risk getting flamed.:gtfo:

Some 706 casting heads were porous and leaked coolant so maybe look for 862s if looking at 07 and earlier engines.
There might be concerns about crank reluctor.

Power wise the 08+ engines with the 243/799 heads would be the ticket but I suspect there are a bunch of additional hassles.

Please don't take my word for it, just use my suspicion of additional things to look at as cause for research rather than buying just the most powerful.

'08 is when pretty much all trucks switched to gen 4 motors/ sensors so you would want to avoid those or the swap will much more complicated, and you also need to know what you're buying if it's from a '05-07 as some trucks and SUV switched to gen 4 motors in those years but most were still gen 3's. Like I said already a L33 would probably be best, it's a gen 3 motor so the cam and crank sensors will be compatible, it has an aluminum block so it wont add weight, and has flat top pistons 799 heads for more power. I believe they can be found in all '05-07 4x4 extended cab trucks and there should be a B in the 8th digit of the VIN number.

Thanks guys, this is what I was looking for. Will do my best to find an L33 motor.

l33
 

the l33 only came in a low percentage of 05 06 and half of 07 modle years extended cab 4wd trucks

If one needs an aluminum Gen III 5.3, the only other choice is the LM4 used between 2003-2005. Except for the block, it's identical to the LM7

My L33 came out of a 2005 Suburban.

Someone swapped it in. No Suburbans normally came with L33's. Maybe an LM4?

Correct!
The yard I got it from listed it as 2005 Sub, with an L33 engine.
I just ran the vin I dl'd from the pcm.
It came out of a 2005 pickup truck.

Fleabay has these available; at a relatively low cost. The seller I bought one
From had a 30 business day turnaround just to pull a motor and ship it to me. I got
my money back. This was like 2 weeks ago.

04-07 l33’s as others have stated is your best bet. They have the better connecting
rods in the lower end; and are pre-Loma ( or - lifter oil manifold assembly)

AKA Gen III.... the L33 is a Gen III engine.

I put an L33 in an 03ish suburban once upon a time. That thing would move! Sold it to a guy in Alabama. Did the Suburban come from Alabama by any chance?

For having a 193/193 cam, plus 243 heads, they seem to do just fine....

L33 is a baby sister to the LS2 , has a unique cam stock, Did not have the hollow LS valves but everything else is the same..

I got one from ATK/Jegs $3200 IIRC.. Bought a core out of a Van for the external accessories. for 375 bucks.. Saved the easter egg hunt putting a stock high accessory package together I didnt have time to build so I bought a long block, its in a Wrangler and so far I havnt spent any time full throttle so more power can wait.. (Its a handful)