5.3swap

please some one chime in and help find out what the best valve diameter is for my heads. they are at the machine shop right now waiting on me to tell them what size i want.

thank you

JRENIGAR

iTrader: (37)

And what heads would that be? Casting #'s and setup would help.

oange ss

iTrader: (50)

no reason to get wrapped up in valve sizes. You can step up to a 2.00" intakevalve if you want. Bigger valves would be shrouded by the small bore anyway.

quicksilverado

iTrader: (8)

I thought valve shroud was not a big issue for FI.

oange ss

iTrader: (50)

it's not, niether is bigger valve sizes especially at extra cost

5.3swap

sorry guys, i was on my way out the door when i posted the question and didnt give the information on it. its a 5.3 block, i'm keeping the bottom end stock as far as crank, rods, and piston. its at the machine shop right now getting hot tanked, honed and cam bearings. the heads are 862's and they are all stock. i will be using an ls1 style intake and 60mm twin turbo set up. i will be using an overdrive trans and probably a 3:23 rear gear. is that enough info.

the guy at the machine shop said i would be better off buying a pair of rhs heads for about $700 vs spending about the same amount to get mine up to that level... any input?

thanks

oange ss

iTrader: (50)

you'd be better off putting the extra money toward better pistons..

5.3swap

hey orange thanks for the input. not trying to debate ya honestly (i'm kinda a newbie to motors) but why. everything i read about these 5.3 lower ends is that they are amazing. big bang theory article for example. i can do better pistons but i wasn't going to if i didn't need it. this will be strictly a street car never gonna see a pair of slicks. the tuner in my area said we'll probably tune for somewhere between 12 and 14 lbs of boost and call it a day.

thanks again, very appreciated anytime i get input on this stuff.

miatainthe10s

Big bang theory was run on 116 oct. Stock heads have gone 1k rwhp. If I would do anything to the heads it would be inconel exhaust valves stock size.

5.3swap

just mentioned that article in regards to the bottom end holding up. I'm not following what they did. orange mentioned i should consider better pistons vs head work. so i asked why, I'm not motor guru so i was/am genuinely curious why.

oange ss

iTrader: (50)

They ran that motor on 118 octane race gas on an engine dyno with TEA ported stock heads, only change being the intake valve size (and porting obviously). If you want 850whp you're gonna need pistons at a minimum to have some degree of reliability. That's just my 2 cents, it's your money.

5.3swap

i hear ya orange thanks for the input. much appreciated. i can get a set of forged pistons for $499 so maybe i'll look into that.

back to the heads... so with boost do you guys thank i should leave well enough alone with the stock heads and direct the $ elsewhere? other then some better springs.

SPRAYED 01

iTrader: (22)

Leave the heads alone. Get mls head gaskets and arp head studs. If you want to spend more money get a good cam and really good springs.

5.3swap

thanks sprayed those are already in the budget i'd love some recomendations on cams though

gnx7

iTrader: (28)

what year is the 5.3?

'05+ rods are LS2 style and a hell of a lot stronger than LS1 style.

5.3swap

2002 5.3