well guys as im finishing up some final touches and adjusments on the suspension end of things i want to start thinking/planning performance my truck is my daily driver so my goal right now is to unlock as much HP as i can without affecting my mileage to much.
my truck has a 4.8 and i heard once somewhere that a 5.3 with 4.8 pistons will have a higher compression ratio. if this is true what are the pros and cons if any? would this simply be a 5.3 with more power and same gas mileage? i wonder if it would be worth it to swap cranks and make mine a 5.3 with bolt ons, tune, leaving my 4.8 pistons and maybe even a small cam upgrade (nothing to serious)? im not the most knowledgeable person with cams so i dont know what id go with if i did, LS1 cam maybe?
im sure lots of questions will pop up as this thread goes on so im hoping you guys can help me out, thanks!

 

I think it takes energy to make power, so I don't see you gas mileage going up after mods

From what you stated, I wouldn't tear into the motor. 1/2 liter isn't going to make enough of a difference to warrant it in my opinion. I'd say get some LS6 (243) heads, something like a 212/218 cam, and some pacesetter headers and off road y-pipe. Oh, and a magnaflow muffler too.

 

swapping crank?... the costs of what you are thinking will probably cost more than just swapping to a 6L.

 

Dont bother swapping a crank without building the whole motor. Wont happen cost wise.

R

 

i lost a few mpg when i went to the cammed and stalled ls1 from the 4.8!!!! I was getting 21 highway and now im getting like 18 highway but city is far worse with the big stall (3800)!!!!!

also i had read something about the wristpin height is different on the pistons!!in other words find a 6.0 or LS1

 

well then am i better off with my 4.8 with bolt ons and a tune or an LS1 swap? which is worth the money? my only problem with swaping motors is i know mine has been taken really good care of, i dont want to swap and buy some1 elses problem.. i dont know anybody with a used LS1 that i could trust. i think for the amount i would spend on a new motor if i just put that money in the 4.8 i might be better off wouldnt i?

 

well it depends on the price and why it came out!!! i bought mine from a wrecking yard, it sat in their insurance claims bin for 7 years through a court fight and finally relased. just so happens that i was the first that called and the price was good for me. The motor had 900 original miles when it came out of the mangled car. Theres not alot of hope for the 4.8 but it depends on how fast you want to be. Honestly unless they ran the motor without oil or with low oil for a while you cant really hurt them.

 

swap to an LS1 and you should be in mid - low 13's with bolt-ons. it would take cammed and stalled and full bolt-on 4.8 with weight reduction to do that.

 

LS1 swap has the added advantage of being an aluminum block (~80lbs lighter) also. That will be my next move...

 

I would do a motor swap first, then do bolt-ons or cam to that motor as time or money allows.