Dont know if this comes as often in here as other forums but I'll give it a try anyways. Plz keep the bs out of this thread, so none of the my vortec 350 beat a 01 5.3 etc etc.

The reason for this thread is that I blew up my l31 again. Yes thats again. So after the 2nd time I'm looking for an upgrade. After a little bit of basic pricing I think a 5.7 rebuild would cost similar to a low mile 5.3. I would bring 6.0s into this but they are more pricey. However I'm well aware swapping to a 5.3 is gonna take a little extra cash. Ill try to categorize this to make it simpler.

Performance: How could they both be compared with both having, say a mild cam and boltons?

Longevity: How many miles will 5.3s last on average? I know theres plenty of 200k+ 5.7s running around but I dont hear about many 5.3s with the kinda mileage.

Economy: any of you guys running around with 5.3 street trucks what kinda gas mileage are you seeing? I was getting around 12mpg in town and 18hwy

Maintenance: Once again 5.3 guys, any major/minor problems? Imo the 350 has been dependable even if the intake sucks.

Cost to mod: While 350's are cheap to mod, How do the 5.3s stack up?

Depending on this goes I'll look into it more as far as wiring/pcm/etc

 

if you want horsepower, then the newer engines are very, very good at that. But if you want low end torque, it is really hard to beat an old school 350 or 383.

 

pound for pound you can make more power with a LS based motor then a old school L31 plus for the money your going to invest in that L31 you can go and get a 5.3 or a 6.0 outta the boneyard slap a nice cam in it and make some really nice power and torque plus theres a couple of peeps on here and GMFS that have done the LS motor swaps in the OBS and from what they say its not that bad to do the swap

 

I answered some.

I always thought of the SBC as the easiest engine to work on, until I started tearing down my 5.3 in the garage. Instead of having every bolt size imaginable on the engine, the Ls motors have 10mm, 13mm, and 15mm bolts. Instead off having to take off three components to get to one thing, the LS has each piece accessible itself. I damn near tore apart the entire engine with three sockets and an impact in 20 minutes.

 

as far as lasting i work on 5.3l and 6.0l that have 200000 plus miles and my truck had 12 miles on it when i got it and i have hammered on it up until now it has 98000 and runs great now trans and rear end is a different story.... lol

 

IMO 5.3 is night and day better in many ways!!I had a 97 with the L31 with cam spray and so forth.