Cobras_Rule

iTrader: (4)

Im learning about the LSX stuff. Whats so hot about 5.3L heads. They a better design or something? Just seems strange to put a smaller motors head on an LS motor. Plz no flames... just tryin to learn.

Sandmann120

iTrader: (1)

5.3 heads have a smaller combustion chamber, allowing you to raise compression. HTH

Cobras_Rule

iTrader: (4)

thats what i figured. is that all? how do they flow compared to an LS1 or LS6 head. would a milled AFR head be better? what aould the compression be with a 5.3 head or a milled AFR?

oange ss

iTrader: (50)

aftermarket compnaies use 5.3 cores for there performance LS1 heads because they are abundant....the heads, even with the smaller chamber, will not in itself give you better performance because the basic port design is the same, you will need to get bigger valves installed and have some port work done....if you have the money for AFR's then by all means get those

ssheets

iTrader: (1)

The chamber ceiling is .030" lower for 61.37cc vs 66.67cc in an LS1. The intake valves are smaller...I think they're 1.85 or close to that? The ports are the same.

So if you're going for a normally aspirated high compression motor they make a great foundation. Once you change the valves you have the equivelant of an LS1 head milled .030", but without the change in valvetrain geometry to worry about.

Just swapping stock for stock is a waste of time and effort unless youat least put in bigger intake valves.

ssheets

iTrader: (1)

Edit: nevermind, I pretty agree .

xfactor_pitbulls

iTrader: (16)

Pretty close, 1.89". The intake side flows slightly better down low and slightly less up high. The exhaust side flows a tad better across the board.

Brandon

ssheets

iTrader: (1)

Thanks, 1.89" now that I see it I remember

So with your comments above a mildly cammed street motor would benfit from the increased compression and flow under the curve. I'd still replace the stock intakes with 2.02" valves to make it worth the effort.