03 tahoe 4.8...want more power

[clementeunknown]

upgrading the valve size inthe 4.8/5.3 head actually hurts flow. a 2.0 was the typical upgrade. a 2.02 is overkill. PRC did back to back tests with 5.3 heads with stock valve vs the 2.0 and the 2.0 valve lost flow.

the typical 2.02 valve theme was used back in the sbc days. these heads flow much better then those heads of those times with smaller valves. some of the better LS heads arent even using 1.6 valves rather alone a 4.8 needing them.s also if youre going to toss 1k at those heads you might as well buy a set from a known manufactor for that price.

the turbo kit from Trick is a nice piece and would do much better for the cost vs performance then other things suggested

Your comparing oranges to apples. If 862s flow better than old school iron heads from the 60s & 70s then with a valve upgrade should help out a lot.

PRC 220cc 5.3L Stage 2.5 CNC Ported Heads

A good P&P job and you buying the valves from e-Bay should run under $1K. The suggestion I made is for the budget minded. Besides if your gonna spend a ton of money to make a fast 4.8 a 6.0 is probably come along and eat the 4.8 for dinner and with less money.

[George C]

Your comparing oranges to apples. If 862s flow better than old school iron heads from the 60s & 70s then with a valve upgrade should help out a lot.

PRC 220cc 5.3L Stage 2.5 CNC Ported Heads

A good P&P job and you buying the valves from e-Bay should run under $1K. The suggestion I made is for the budget minded. Besides if your gonna spend a ton of money to make a fast 4.8 a 6.0 is probably come along and eat the 4.8 for dinner and with less money.

increasing size of valve isnt everything with flow. also for the price you jsut mentined you could find a set of ported heads from a manufactor for that price

the sbc heads needed a valve increase since they werent a good design as todays. increasing the valve has shown to hurt. TSP has mentioned this a few times on ls1tech