what are the real differences..like power. torque. and how well they respond to mods. what are the cubes for both blocks

dumb question- 5.3 extcab = 4.8 rcsb?

 

The low end tq is much better on the 5.3. A stock 4.8 doesn't really start pulling good until 4000 then hits the rev limiter at 5500.

 

so with a little tuning work they could be the same?

 

I don't have nearly as much experience with tuning of stock or near stock engines as many others on here but i'd say with a tune a rcsb 4.8 would outrun an ecsb 5.3. In stock form (most years)the 4.8 is down 10hp 30lbs tq.

 

oh ok well thanks for the info

 

No prob. My 05 had 180 miles on it before it was no longer stock and by 1200 miles it had a Radix on it. It would have had it on it sooner but I had to wait 2 weeks for it to come in. I can't leave well enough alone.

 

....mine bounces off the limiter at 6k. No tune.

But you're right about the torque. I actually mock-raced my friends '01 Suburban with a locker and lost off the line. I caught up and passed as the revs went higher.

 

my 2005 was limited to 5500.

 

Your '05 also has an internal fuel filter. They change things from year to year.

 

my 2003 4.8L likes to eat 2006 5.3's for lunch

seriously... equivalently modded side by side on the 1/4, took him by 0.3 seconds 3 times straight... high revving 4.8L FTW!