nickleahy23

iTrader: (1)

My friend has had these aluminum 862 casting heads since middle of highschool, which was about 04 or so...i finally just did some looking around and it seems they are 5.3/4.8 heads? he was told they were ls1 heads...any input? we were just curious on them since they have been in the basement for a long *** time..

Bigschwerm

iTrader: (26)

That is correct...here is what i found.

706 & 852 & 862
Head: 1999+ LR4 4.8-liter Truck
1999+ LM4 / LM7 5.3-liter Truck

Material:Aluminum
Part Number: 12559852, 12561706 ,12559862

Combustion chamber Volume:61.15cc
Compression Ratio:9.5:1
Intake port Volume:200cc
Exhaust Port Volume:70cc
Intake valve Diameter:1.89-inches
Exhaust valve Diameter:1.55-inches

What you need to know: These small combustion chamber truck heads offer no advantage over an LS1 head except the smaller combustion chamber. This along with milling of the deck surface will allow a slightly higher compression ratio to be achieved. Because of the smaller intake valve installed in these heads a valve upgrade is practically mandatory.

LightFighter

iTrader: (1)

you would be better off grabbing a set of CNC'd LS6 heads that are milled to give you a little more compression

Mangled03gmc

iTrader: (95)

Nothing special, as stated in the first rep. 4.8 5.3 heads. LS1 heads were 241, the ls6 heads are 243's and if IIRC 799's
Ls6 have a 64.4 cc chamber vs the 61cc chamber on them.. 243's will out flow them by alot, unless you have the runners worked, bigger intake valves added to the ones you have

nickleahy23

iTrader: (1)

thanks guys..i wasnt wanting to buy them, we just forgot about them and finally wanted to know what they really were lol...