Best LS Heads for 6.0/5.3/4.8 | Cathedral Port Heads vs Rectangular
Best Factory LS Heads Explained
The LS engine family is one of broad capabilities. From basic V8 torque to haul loads in a pickup truck to supercharged high rpm performance found in muscle cars, the LS is a popular and easy to build engine platform that made the “LS swap” a household name. If you’re curious about how to do an LS swap you don’t have to go any further than our Toolbox for great LS content. While some of the performance differences in the various LS engines are due to the overall displacement, the factory cylinder heads are known to be a great performance upgrade due to their cylinder head port design, near universal interchangeability from LS engine block to engine block, great airflow, and aluminum construction. This makes the stock cylinder heads some of the best budget LS heads for low dollar builds.
This makes going up or down in combustion chamber size or intake/exhaust valve size as simple as sourcing a good set of used heads and swapping your current heads out. While there are several great aftermarket LS cylinder heads, for those on a budget swapping to a different OE head is a great option. With a simple LS head swap you can raise or lower compression, increase airflow, and more. When paired with an aftermarket LS performance camshaft serious gains can be had for what is essentially nut and bolt work and some new gaskets.
Cathedral Port Heads vs Rectangular | LS Head Port Design
The LS cylinder head can be found with two different intake port designs. Our LS engines list will help you determine their original usage. These intake ports are known as cathedral port and rectangular port and were used across various LS engine applications. The cathedral port, as its name implies, is shaped like a church’s cathedral window, coming to a point at the top. The rectangular port is a more traditional intake port that is available in two configurations (standard and raised port).
While they can be interchanged for each other, the intake manifold must match. You cannot run a rectangular port intake on cathedral port heads for example. Also take note that some heads have valve locations/sizes that interfere with the engine block bore size. While some have gone to the effort of new exhaust valve seats and smaller exhaust valves for clearance, for most applications it isn’t worth the effort, and it is simply best to use a known head that will clear your block’s bore diameter/spacing.
LS Cathedral Port Heads
- Design: Tall and narrow like a cathedral window
- Application: Found on early LS engines like LS1, LS6, and some truck engines
- Characteristics: Smaller ports create higher velocity airflow, improving low- to mid-range torque
Common Casting Numbers:
- 241: Used on 4.8L and 5.3L truck engines and early LS1s, with 67cc chambers and 2.00/1.55-inch valves
- 852 and 706: Smaller 61cc chambers and 1.89/1.55-inch valves, good for high compression builds
- 799: 65cc chamber and 210cc intake runner, valuable for trucks
- 243: Sometimes called LS2 heads, rare, with 71cc chambers found in some trucks (035 or 317 castings)
Rectangular Port Heads
- Design: Wide and rectangular
- Application: Used on higher-performance LS engines like LS3 and L92
- Characteristics: Larger ports provide more airflow at high rpm, ideal for performance and racing
Common Casting Numbers:
- 823 and 821: Found on LS3 and L92 engines
Raised Rectangle Port Heads
- Design: Raised, rectangular intake ports
- Application: Used on high-performance engines like the LS7
- Characteristics: Improved airflow by straightening the intake path, crucial for high-performance
Common Casting Numbers:
- 8452 and 770: Found on LS7 engines
As we mentioned above, it is important to understand that while most any LS head can be physically bolted to any LS engine block, the engine block’s bore diameter and spacing must be confirmed to ensure that you avoid clearance issues. LS head bolts are 11mm except for LS9, which are 12mm. All LS heads use 8mm upper bolts. This makes LS heads easily interchangeable (except those LS9s with the larger bolt holes) provided the matching intake manifold, stock or aftermarket, is also utilized. Our mock up heads for LS engines are a great option when performing an LS swap and you need to confirm clearance and build out induction plumbing and more.
- LS1 and LS6 Engines: Use LS1, LS6, and LS2 cathedral port heads or their truck equivalents
- LS2 Engines: Can use LS1, LS6, LS2 cathedral port heads, and LS3/L92 rectangular port heads due to their larger 4.000-inch bore
- LS3 Engines (6.2L variants): Can use any head except LS7 rectangular-port heads
- LS7 Engines: Can use any LS-series head, but smaller heads are not recommended for performance
Best Heads for 4.8 LS
The 4.8 LS engine is the smallest of the LS engine family offerings, but that doesn’t mean it can’t be a great budget build option for your LS swap. You can make some respectable 4.8 L horsepower with carefully curated parts. Originally found in GM trucks and SUVs as the Vortec 4800 in both Gen III and Gen IV examples under RPO codes LR4, LY2, and L20, these engines are plentiful and cheap in most salvage yards. The 4.8 LS could be had with one of three cylinder heads: 706 heads, 862 heads, or 799 heads. We’ll run through each iteration below, providing chamber and valve sizing, and their pros and cons to help you decide what are the best LS heads for your build.
706 Heads
- Application: Found on many 4.8L and 5.3L engines
- Valve Sizes: 1.89-inch intake and 1.55-inch exhaust
- Chamber Volume: 61cc
- Pros: Smaller chambers for higher compression, common and affordable
- Cons: Smaller ports may limit high-rpm performance without modifications
862 Heads
- Application: Used on early 4.8L engines
- Valve Sizes: 1.89-inch intake and 1.55-inch exhaust
- Chamber Volume: 62cc
- Pros: Slightly larger chambers than 706 heads for a balance of compression and airflow
- Cons: Limited high-rpm performance without porting work
799 Heads
- Application: Often found on higher-end 4.8L and 5.3L engines
- Valve Sizes: 2.00-inch intake and 1.55-inch exhaust.
- Chamber Volume: 65cc
- Pros: Better airflow compared to 706 and 862 heads; larger intake valve improves performance
- Cons: Less common, slightly larger chambers may reduce compression compared to 706 heads
For a 4.8 build the 706 heads are often the clear winner here as the best flowing LS heads for the 4.8 LS, providing a nice bump in compression while flowing enough for the engine’s given displacement. Some bowl blending and mild porting with a head porting kit will really wake up a set of 706s as well. If you’re going to add boost, then consider the 799 heads to drop the compression a bit. Remember, it’s all in the combination, so pick the proper parts for your build and you’ll be happy with the performance outcome.
Best LS Heads for 5.3
The 5.3 LS engine is one of the most popular engines of the LS engine family, seeing enormous potential for cheap horsepower in LS twin turbo applications. Originally found in GM trucks and SUVs as the Vortec 5300 in both Gen III and Gen IV examples under RPO codes LM7, L59, LM4, LY5, LMG, LMF, LH6, LC9, LH8, LH9, and L33 (the Vortec H.O. 5300), these engines are plentiful and still a decent value in most salvage yards. Note that there is a 5.3 used in FWD car applications, the LS4, that should be avoided due to the differences in being used for FWD. The 5.3 LS could be had with one of four cylinder heads: 706 heads, 862 heads, 799 heads, or 243 heads. We’ll run through each iteration below, providing chamber and valve sizing, and their pros and cons to help you decide what are the best LS heads for your build.
706 Heads
- Application: Found on many 4.8L and 5.3L engines
- Valve Sizes: 1.89-inch intake and 1.55-inch exhaust
- Chamber Volume: 61cc
- Pros: Smaller chambers for higher compression, common and affordable
- Cons: Smaller ports may limit high-rpm performance without modifications
862 Heads
- Application: Used on early 4.8L engines and many 5.3L
- Valve Sizes: 1.89-inch intake and 1.55-inch exhaust
- Chamber Volume: 62cc
- Pros: Slightly larger chambers than 706 heads for a balance of compression and airflow
- Cons: Limited high-rpm performance without porting work
799 Heads
- Application: Often found on higher-end 4.8L and 5.3L engines
- Valve Sizes: 2.00-inch intake and 1.55-inch exhaust.
- Chamber Volume: 65cc
- Pros: Better airflow compared to 706 and 862 heads; larger intake valve improves performance
- Cons: Less common, slightly larger chambers may reduce compression compared to 706 heads
243 Heads
- Application: Often referred to as LS6 heads, used on LS2 engines, sometimes found on high-performance 5.3L engines
- Valve Sizes: 2.00-inch intake and 1.55-inch exhaust
- Chamber Volume: 64cc
- Pros: Excellent airflow, larger valves, and chambers provide a balance of performance and compression
- Cons: Less common and more expensive than other stock heads
Much like the 4.8 LS, the 706 (or even the 862) heads are usually the preferred casting for most 5.3 LS budget builds using stock heads. The 243s, much like the 799s, are good for lowering compression in boosted applications (or if you’re willing to shave the heads a bit to bump the compression back up). But as a direct bolt on with zero machining other than some bowl blending and hand porting, the 706 head is really the stand out winner for the highest flowing LS heads for the 5.3 L engine horsepower needs of the budget builders in the audience.
Best LS Heads for 6.0
Moving up the displacement ladder of the LS engine family, we have the 6.0 LS engine. Originally found in GM trucks and SUVs as the Vortec 6000 in both Gen III and Gen IV examples under RPO codes LQ4, LY6, L96, LS2, L76, LQ9 and L76 (VortecMax), and LFA and LZ1 (Vortec 6000 Hybrid) these engines are a bit harder to find used and come with a comparable price tag in most salvage yards. The 6.0 LS was also found in several Gen IV car applications under RPOs LS2, L76, and L77. The 6.0 LS could be had with one of six cylinder heads: 317 heads, 243 heads, 799 heads, 821 heads, 823 heads, or 364 heads. We’ll run through each iteration below, providing chamber and valve sizing, and their pros and cons to help you decide the best LS heads for your build.
317 Heads
- Application: Found on LQ4 and LQ9 engines
- Valve Sizes: 2.00-inch intake and 1.55-inch exhaust
- Chamber Volume: 71cc
- Pros: Larger chambers reduce compression, making them great for boosted applications, affordable, and widely available
- Cons: Lower compression can be a drawback for naturally aspirated builds
243/799 Heads
- Application: Found on LS2 and some LQ9 engines
- Valve Sizes: 2.00-inch intake and 1.55-inch exhaust
- Chamber Volume: 64cc (243), 65cc (799)
- Pros: Excellent airflow, larger valves, good balance of performance and compression, commonly upgraded from stock heads
- Cons: Less common than 317 heads, more expensive
821/823 Heads
- Application: Found on LY6 and L76 engines
- Valve Sizes: 2.165-inch intake and 1.59-inch exhaust
- Chamber Volume: 68cc
- Pros: Larger ports and valves provide excellent high-rpm performance, great for high-performance builds
- Cons: Larger chambers can reduce compression, less common than 317 heads
364 Heads
- Application: Found in some high-performance 6.0L applications
- Valve Sizes: 2.00-inch intake and 1.55-inch exhaust
- Chamber Volume: 65cc
- Pros: Good balance of airflow and compression, suitable for various performance builds
- Cons: Less common and can be more expensive than other stock options
When it comes to the larger displacement of the 6.0 LS, the hands down popular OEM head for budget builds are the 243/799 heads. These castings are the best stock heads for 6.0 LS and provide larger valves with good NA compression values. For boosted applications, the 821/823 castings are usually the go to when bolting on that low buck turbo kit. You really can’t go wrong with either for your 6.0 LS build, just be aware of the head casting’s merit for NA or boosted use.
Best Heads for 6.2 LS
Lastly, we have the 6.2 LS engine. Originally found in GM trucks and SUVs as the Vortec 6200 in Gen IV examples under RPO codes L92, L9H, and L94 these engines are harder to find used than all the other LS engines previously mentioned and come with a comparable price tag in most salvage yards if you can find one. The 6.2 LS was also found in several Gen IV car applications under RPOs LS3, L99, and the supercharged LSA and LS9 versions. The 6.2 LS could be had with one of three cylinder heads: 823 heads, 5364 heads, and 821 heads. We’ll run through each iteration below, providing chamber and valve sizing, and their pros and cons to help you decide the best LS heads for your build.
823 Heads
- Application: Used in LS3 engines
- Valve Sizes: 2.165-inch intake and 1.59-inch exhaust
- Chamber Volume: 68cc
- Pros: Excellent airflow and performance, larger valves, ideal for naturally aspirated applications
- Cons: May require tuning and modifications for optimal performance in forced induction setups
5364 Heads
- Application: Used in L92 engines
- Valve Sizes: 2.165-inch intake and 1.59-inch exhaust
- Chamber Volume: 68cc
- Pros: Like LS3 heads but with slightly larger chambers, great for high-RPM performance
- Cons: May have clearance issues in some engine bays due to larger size
821 Heads
- Application: Used in LS9 engines
- Valve Sizes: 2.16-inch intake and 1.59-inch exhaust
- Chamber Volume: 68cc
- Pros: Supercharged application-ready, excellent airflow, and performance
- Cons: Expensive and less common for non-supercharged builds
When it comes to these 6.2 LS heads it is almost a toss up as to their performance comparisons. The 5364 heads are die cast, whereas the 823/821 heads are sand cast. The die casting provides a bit smoother port wall surface than the rougher sand casting, but the 823/821s have a slightly larger exhaust port, often providing a roughly 10 hp gain over the 5364 heads when using a performance camshaft in a budget build. This is usually dependent upon exhaust header or manifold used, primary tube size, etc. At the end of the day, these heads are nearly identical when it comes to highest flowing LS heads for the 6.2 (in OEM castings).
LS Cylinder Heads Casting Numbers Location
The casting numbers we’ve been discussing are cast with the cylinder head itself and are a way for GM to determine what casting facility the cylinder head came from in case there are problems down the road, such as premature wear or failure. There are two main locations where these LS heads casting numbers can be found. The first, and easiest to see for confirmation, is on the outside corner of the cylinder head. This corner, just above the exhaust flange, will have the casting number visible for quick verification. The second LS heads casting number location, which can be used as backup confirmation, is under the valve cover cast into the cylinder head (usually in the middle). Not all heads will have this second location, but it is worth a look. Often there will be additional markings/codes on the ends of the cylinder heads that can be used in an Internet search to find additional details on the specific heads you are considering.
Best Factory LS Heads | LS Head Casting Numbers
Now that we’ve gone through the OEM LS cylinder head offerings you can more easily determine which cylinder head may work the best for your budget LS build. Factoring things such as cost, availability, valve size, combustion chamber/compression ratio, and more along with future engine plans will help you navigate these choices and come to a decision on what cylinder head will work for you.
LS Heads Identification Guide
Be it a salvage yard run, or walking the isles at a swap meet, knowing your LS cylinder heads by intake port, casting number, and other factors will ensure you’re buying the right heads for your LS build project. Below we have created a simple infographic that you can print out or save on your mobile device for that next LS budget build shopping excursion.
Best LS Head Gasket
It is common for many to simply toss a pair of parts store head gaskets on a build and call it good. But there is a lot of science that goes into a quality LS head gasket for proper sealing, especially against dissimilar metals like iron block and aluminum heads. Head gaskets can even affect compression ratio and chamber volume when you start messing with gasket thickness options. When it comes to the LS engine family, both standard composite and multi-layer steel (MLS) have been used in OE production. In the aftermarket you’ll find these materials in various options for bore size, gasket thickness, and more. Determining the best head gasket material for your application will ensure that your LS engine’s combustion chamber is properly sealed.
Consideration and Impact of LS Head Gasket Specifications
- Thickness: Thicker head gaskets can affect compression ratios and squish areas, potentially altering engine performance. They are often used in boosted applications to lower compression. Match the gasket thickness to maintain desired compression ratios.
- Material: MLS is most common for LS engines due to their robust sealing properties and ability to withstand high cylinder pressures and temperatures. Composite is generally used in stock or mildly modified engines where MLS gaskets are not necessary.
- Cathedral port heads typically use standard MLS or composite gaskets depending on the application and compression requirements.
- Rectangular port heads often require MLS gaskets to handle increased cylinder pressures due to their larger bore and higher performance applications
- Raised rectangle port heads benefit from MLS gaskets to ensure a dependable seal under high-performance conditions.
- Watch for early LS heads (pre-’99) with combustion face notch, these used composite gaskets originally and will often not seal properly using MLS head gaskets unless a special gasket is used.
