Have a LS1, Stock heads...Are the Z06 heads better? If so why?

 

I've been reading about heads lately. No expert, but I'll offer that there is a TON of information on the web about LS heads. It'll make your head swim.

The LS1 got the 241 heads. The LS6/Z06 got the 243 heads.

The 243 heads flow better, and give a slight bump in compression? (somebody check me on that). Also specific to the 243 heads from the Z06 are the light weight sodium filled valves, which are no longer available I believe, so that makes them a bit more valuable.

the 243 heads also came on other LS engines, including some later trucks, etc. So you're not limited to sourcing heads only from a Z06; but you won't get the sodium filled valves.

I've also read that the 799 heads are identical to the 243 heads, but that the casting may be slightly rougher; but if you are having them ported that's a non-issue.

Hope this helps.

 

799's and 243's ive seen looked similar in casting. and they both sucked rather badly, at least in comparison to even so much as a Honda head. if you have the heads off, at least smooth them out with sandpaper w/o changing the shape. doesnt require being adventurous to do that much for an easy ~10rwhp.

 

Your stock heads ported can make power, you just have to go to the right place. 243's will make more power but then your forking out an additional $400-500 bucks on the heads a lone for a few extra hp. I was going to do that on a recent heads cam job but decided to go with the high compression 241's from advanced induction because the shop doing the install said the numbers are VERY close to the 243 numbers.

 

If you need anymore info on the comparison do a Google search there's about 16 billion posts on this topic on various LS sites.

 

what is a 241 head? Is this an OEM, head?

 

hit google or search.

LS1's and LS6's 1996-2004 came with 241's. 241 = 863 i THINK you'd have to double check me.
Z06 ls6's came with 243's. 799 = 243.


Pasting the below from a truck forum:

Head Casting Info

ALL Gen III heads are interchangable.


Here is a list of a few casting #'s:

933 97 aluminum perimeter bolt 5.7
806 97-98 aluminum perimeter bolt 5.7
853 99-00 aluminum center bolt 5.7
241 01-03 aluminum center bolt 5.7 (some late MY00 cars got 241 castings)
243 LS6 aluminum center bolt 5.7
862 and 706 99 and up 4.8-5.3 truck heads
873 99-00 LQ4 6.0 iron center bolt heads
317 01 and up LQ4 6.0 aluminum center bolt heads
035 02 and up LQ9 6.0 aluminum center bolt heads

Even more info:

Casting Number 241
Head: 1997+ LS1 5.7 Litre Passenger Car
Material: Aluminimum
Part Number:
12559806 (1997-98) Chambers = 69cc
12559853 (1999-00)
12564241 (2001-03)
Combustion Chamber Volume: 66.67cc
Compression Ratio: 10.1:1
Intake Port Volume: 200cc
Exhaust Port Volume: 70cc
Intake Valve Diameter: 2.00 inches
Exhaust Valve Diameter: 1.55 inches


Casting Number 243
Head: 2001 LS6 5.7 Litre Passenger Car
Material: Aluminimum
Part Number:
12564243
Combustion Chamber Volume: 64.45cc
Compression Ratio: 10.5:1
Intake Port Volume: 210cc
Exhaust Port Volume: 75cc
Intake Valve Diameter: 2.00 inches
Exhaust Valve Diameter: 1.55 inches

Casting Number 706
Head: 1999+ LR4 4.8 Litre Truck
1999+ LM4 /LM7 5.3 Litre Truck
Material: Aluminimum
Part Number:
12559852
12561706
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

Casting Number 373
Head: 1999-2000 LQ4 6.0 Litre Truck
Material: Cast Iron
Part Number:
12561873
Combustion Chamber Volume: 71.06cc
Compression Ratio: 9.5:1
Intake Port Volume: 210cc
Exhaust Port Volume: 75cc
Intake Valve Diameter: 2.00 inches
Exhaust Valve Diameter: 1.55 inches

Casting Number 317
Head: 2001+ LQ4 6.0 Litre Truck
Material: Aluminimum
Part Number:
12572035
Combustion Chamber Volume: 71.06cc
Compression Ratio: 10:1
Intake Port Volume: 210cc
Exhaust Port Volume: 75cc
Intake Valve Diameter: 2.00 inches
Exhaust Valve Diameter: 1.55 inches



It takes about .005" milling of the block deck to remove 1cc of volume. It takes .007" milling to remove 1cc from an LS1 head

Simple Milling Math:

You have a stock 66cc chamber and you want to get down to 63cc

66-63 = 3. You have to remove 3cc's

.007 x 3 = .021. So to get your 66cc chambers down to 63cc you'd have to mill ~.021.

You can also do the reverse, say you want to mille a head .030 to figure out how many CC's that removes you take .030 / .007 = ~ 4.28. Milling a stock 5.7 head .030 puts your chamber at ~ 62.



241 cast heads were Die Cast which is a process that smooths up the ports a bit compared to the Sand Cast procedure that was done on the 806 and 853 heads. Once ported any "advantage" the 241 cast had is moot.

 

Yes the stock LS1 Head on Later Fbodies, Vette's and first year of the GTO.

 

Thanks for taking the time to post this...This is just what I need to know....

 

So I have a set of 243 heads....there at the shop..Have some work done, before we put them on..

 

heads...........My 243 heads working great...

 

Thank you! Always hate to see a thread fade off into the ether with no conclusion.
That said, what work did you have done, and what results did you see?