Ok guys, I'm always hearing different opinions about what the difference is between all the LS heads.

The way I understand it is that the 317, 241, and the 243 all have the same valve size and port design but different combustion chamber size?

799 is the same as a 243?

And you guys can list the other head casting numbers and their differences...

And what is the difference between the old 5.3 heads and the new ones? I think it's 862 and 706...

And the difference between the old 5.7 LS1 heads and the new ones? I think it's 863 and 241...

 

I believe this is most of them...

https://www.performancetrucks.net/fo...&highlight=862

 

241 & 853
Heads: 1997+LS1 5.7- liter passenger car
Material: Aluminum
Part Number: 12559853 (1997-98)
1255853 (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


What you need to know:
The standard issue LS1 heads is best all-around head for the street / strip engines . A thorough porting and millimg job plus a valve upgrade on these will really wake up your engine.The heads have undergone only minor revisions since their introduction in 1997 , most notably a switch from perimeter to center valvcover bolt configuration for the 1999 model year. Each style has its own dedicated valvecovers and coilpacks mounting apparatus.


243
Heads: 2001+ LS6 5.7 liter passenger car
Material:Aluminum
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

What you need to know:
The LS6 cylinder heads is essentially a tuned-up version of the LS1 head. At 65cc, the combustion chamber is slightly smaller and more efficient than the LS1. The more efficient design shortens burn times and ultimately means less ignition timing advance is required to produce the same power. And because less timing allows more efficient combustion, the Ls6 heads allow the engine to produce more torque. The exhaust port is a unique D-shape that improves flow. LS6 heads are the best choice only when all-out power is needed. Be prepared for a big price tag at the dealer or steep core charge from your head porter.


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.


873
Head: 1999-2000 LQ4 6.0-liter Truck
Material: Cast Iron
Part Number: 12567873

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

What you need to know: The LQ4 heads are found on the low-performance version of the 6.0-liter truck engine. They offer a large combustion chamber that lowers compression ratio making them perfect for a forced induction application. Swapping on the LQ4 head drops the compression ratio of a typical LS1 engine to 9.:5.1 Cast-iron casting are heavy!


317
Head: 2001+ LQ4 6.0-liter Truck
Material:Aluminum
Part Number: 12562317

Combustion chamber Volume:71.06cc
Compression Ratio:9.4:1
Intake port Volume:210cc
Exhaust Port Volume:75cc
Intake valve Diameter:2.00-inches
Exhaust valve Diameter:1.55-inches

What you need to know: The LQ4 head received aluminum heads starting in models year 2001. All other features are the same as previous years iron heads. This is the workhorse head for street / strip turbo and blower cars.


035
Head: 2002+ LQ9 6.0-liter Truck
Material:Aluminum
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

 

I know this is an old post, hoping someone with a lot of knowledge reads it and responds. But I was wondering if I could use the 317 head on my 4.8? Also how much compression would I end up with (est)? my 4.8 has 9.5, from what I have read. I want to add either a super charger or a turbo to that motor. What cam would be ideal, getting max performance and still be streetable and practical?

 

keep the stock 4.8 heads IMO. i doubt you're planning anything over 15psi and that 4.8 would be a complete dog out of boost with lower compression.

 

What would be a "upgrade" from the 706 heads? i have the coolant leak from mine and dont want to risk having this again. I have a 5.3 and it's my daily driver

 

243 or 799

 

What is the 799 ?

 

Same as the 243 just on the newer (07-13) 5.3s

 

Had the same problem of leaking head on my 2001, had to carry a bottle of distilled water all the time. I'm cooking up a cathedral port head project on paper~ what cathedral port head(s) didn't leak...................