Llaverito

iTrader: (4)

Im running 20psi on e85 and it's a 07 5.3

Boosted Firehawk

iTrader: (11)

I would like to do the same in my car! What heads were on that engine before? 799?

Llaverito

iTrader: (4)

yes 799 but i got it as a short block so i slapped some 706s i had laying around

2000RATA

They are different. The 5.3 (706) head has a smaller combustion chamber and smaller different shaped intake runner than a 862 head. The 862 is the same as a 241 and 806 ('98) heads. Except for the notch on the deck surface. A ported 706 head would be the ticket on a boosted budget 5.3. The reason is the intake runner is still smaller ported than a 799/243 head unported and will out flow either of them by 40+ cfm. So what you have is the compression you want, a head with great velocity and flow for off boost and transient response. Simply put ported 5.3 heads would murder a set of unported 799/243's out of boost or in.

MillsMotorvation

Good info!

Black98s10

I was reading on s10forum this morning about some 706's being crappy castechs, that are prone to cracking. Anyone have more info on this what years are crap?

Ferocity02

iTrader: (60)

Mine were the 706 heads that were prone to cracking, so I replaced them with milled 799's. Same SCR but flow better. The 706's looked okay though when I removed them.