slowrollin93

iTrader: (7)

Alright so I am getting a ls1 shortblock, its going to replace my old tired 5.3 eventually when it decides its had all it can handle or I just get bored one day. Is there any adverse performance effects to taking the heads off my 5.3 to run on the ls1, its out of an 04 GTO. I know the intake valve is smaller but i have heard they flow about the same and I know the chambers are a little smaller on the 5.3s too so up goes the comp ratio. I just want to keep it all budget, getting one hell of a deal on the shortblock and dont really want to dish out more money for heads since i will have a pretty much worthless 5.3 that will probably make a trip to the scrap yard after i take it out.

Jon

Cvaught

iTrader: (13)

I would like to know this also. bump

SOMbitch

iTrader: (8)

Not worth it unless you go with bigger valves and port.... They don't flow stock with an untouched 853 or 241 casting.

ss.slp.ls1

iTrader: (36)

You can buy low mile 853's or 241's for $100 all day, that's what I would do.

5_02ls1

iTrader: (20)

i see hear this alot...but here are the facts....both heads flow damn near the same...and you get a nice bump in compression...ive ran the 5.3s but they were hand ported and yes with the smaller valve...idk how much power i gained but the car was alot tourqier all through the powerband than it was with the 806 castings...

5.3LJimmy

iTrader: (10)

The 5.3 heads flow almost identical to the LS1 head. The smaller valve doesn't hurt them much at all. There is a flow sheet that I just reposted that compares the LS1, LS6, 6.0, & 5.3 stock heads. At .600 lift on the intake the LS1 flows 227 and the 5.3 is at 226. The numbers are within a couple CFM thru the entire lift range.