The GEN III platform has truly allowed enthusiasts to mix and match components to their heart’s desire as GM has unwaveringly thrown it’s support behind the all-aluminum powerhouse. And with said support comes the multitude of LS1 Heads available from the factory as a bolt on or swap option for anyone wanting to swap a LS1 into a different chassis.
After all if cost were no issue, wouldn’t we all be driving some unaffordable supercar? And so in this quest for performance, we’d like to take this time and outline some of the more readily available heads for your LS1 swap.
Part Number : 12559853 ( 1997-2000 ) 12564241 ( 2001-2003 )
Where this LS1 Head can be found : 1997+ LS1 Chevy Camaro, Pontiac Firebird, Chevy Corvette, and more
Intake Port Volume : 200cc – Exhaust Port Volume : 70cc
These are the standard LS1 heads found on your everyday stock motor, and while you most likely already own these the real gain is when you have them milled .030.
This will yield a compression gain up to 10.9:1 on the stock LS1 which is a very cheap and easy method to gain some extra horsepower. Take note if you are swapping from a 1997 block, in which a is a change in the valve cover bolt configuration.
Part Number : 12564243
Where it can be found : 2001+ LS6 Corvette and more
Intake Port Volume : 210cc – Exhaust Port Volume : 75cc
One of the widely common swaps is the LS6 heads which net a compression ratio close to 10.5:1 which will not only gain in performance but lower load on the motor by way of reduced ignition timing advance.
With changes to improve flow and performance over the LS1 counterparts, the LS6 heads with a very different D shaped exhaust port can also be milled .030 to get to a 11.2:1 compression ratio.
Not as an affordable option compared to many aftermarket competitors, but these heads can still be found from people wanting to upgrade from their existing stock configuration.
Part Number : 12559852 – 12561706
Where it can be found : 1999+ LR4 Equipped 4.8 liter truck such as the Sierra, Avalanche (pictured), Silverado, or LM4 equipped 5.3 liter truck and more.
Intake Port Volume : 200cc – Exhaust Port Volume : 70cc
Perfect for those wanting to piece together a motor of their own, these heads are nearly identical to the LS1 heads and deliver a compression ratio of 11:1 but come with smaller intake valves at the benefit of a much lower price tag. You can also mill the deck .030 to raise the stakes to a much more healthier 11.5:1 compression ratio.
Q : What if I am building a turbo LS1 and want lower compression with my new LS1 Heads?
A : We would certainly hope you opted for the iron shortblock from a truck if you wanted forced induction, but if you are looking for lower compression, we’ve got a few choices from the factory.
Part number : 12572035
Where it can be found : 2002+ LQ9 6.0 Liter Truck
Compression Ratio : 10:1
Intake Port Volume : 210cc – Exhaust Port Volume : 74cc
These LQ9 heads are found usually on the Cadillac Escalade from 2001 on up and are most comparable to the LS6 head but with improved flow and design. With a 72cc combustion chamber and a relatively affordable price range, this head is ideal for forced induction application such as turbo or supercharger.
Part Number : 12562317
Where it can be found : 2001+ LQ4 6.0 Liter Sierra, Silverado, and more
Compression Ratio : 9.4:1
At an affordable price, these LQ4 heads will give your tuner a little wiggle room if you are wanting the ultimate in GEN III performance with a form of forced induction.
Slapping these heads on a stock block LS1 will net you a perfect compression ratio of 9:1 which is a great choice for forced induction applications such as turbo or supercharger. These heads will lower your compression to a streetable and friendly level, where upwards of single digit psi is perfect. This brings us to the conclusion of our comparison at GM stock LS1 Heads, please let us know if you have any questions or comments below.
If you haven’t already take a look at our LS1 Swap free mods that every enthusiast should make sure and perform before swapping their LS1 into the donor car of their choice.
Happy swapping!
- Pro Street Staff
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