boot85

iTrader: (2)

I have noticed that the cast iron headed 6.0s have a lower compression ratio than the aluminum but both heads have the same cc combustion chamber. That makes think that the iron headed ones have more of a dish than the aluminum ones. Is this correct, I have been wondering this for a while now.

Casting Number 12562317 or 12572035

2001-2004 LQ4/LQ9 equipped truck
Material: Aluminimum
Combustion Chamber Volume: 71.06cc
Compression Ratio: 10:1
Intake Port Volume: 210cc
Exhaust Port Volume: 75cc
Intake Valve: 2.00 inches
Exhaust Valve: 1.55 inches
Part Number: 12572035

Casting Number 12561873

1999-2000 LQ4 equipped truck
Material: Cast Iron
Combustion Chamber Volume: 71.06cc
Compression Ratio: 9.5:1
Intake Port Volume: 210cc
Exhaust Port Volume: 75cc
Intake Valve: 2.00 inches
Exhaust Valve: 1.55 inches

wildcamaro

iTrader: (15)

The 6.0 lq9 is 10:1 compression bc of flat top pistons (cadillac escalade) and ALL 6.0 lq4 are 9.5:1 compression bc of dish pistons whether aluminum or cast iron heads.

boot85

iTrader: (2)

Ok, so the only difference is the head material, probably cam profile and the different crank spacing for the older trannys, right?

wildcamaro

iTrader: (15)

Yep as far as I know...Im pretty sure they have same cam though

boot85

iTrader: (2)

I wonder why it looks like the aluminum headed LQ4 has higher compression.

boot85

iTrader: (2)

I passed on a cast iron headed engine in favor of the aluminum headed version.

wildcamaro

iTrader: (15)

Good move

88Fbody6L

iTrader: (5)

Lq9 is the way to go if you can find a good deal. Better rods, higher compression...You can also find a set of 243 cast heads and bump the comp up to 10.9.