Used 823 Cylinder Head #009
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Used GM LS 823 Cylinder Head, Rectangular Port
This is a used OEM-style GM LS 823 cylinder head. The 823 casting is a rectangular port LS cylinder head commonly found on later Gen IV 6.0L and 6.2L LS-based engines, including applications such as LS3, L92, L99, L76, L77, LY6, L96, L94 and L9H.
823 heads are one of the most popular factory rectangular port LS heads. They offer significantly better airflow than earlier cathedral port truck heads such as 706, 862, 241 and 317, making them a strong option for performance LS builds.
These heads work especially well on 6.0L and 6.2L LS combinations where the larger rectangular intake port, larger valves and strong factory airflow can be used properly. They are commonly used in naturally aspirated, cammed, turbo and supercharged LS builds where a high-flowing OEM GM casting is preferred over aftermarket cylinder heads.
Important Condition Information
This is a used cylinder head and condition may vary between individual units. Some heads may be more complete, while others may be missing valves, springs, retainers, seals, bolts, plugs or other small parts.
Some used heads may have cosmetic wear, dirt, oxidation, gasket residue, broken bolts, damaged threads or other defects. Please see the product pictures carefully for actual condition and included parts.
Important Fitment Information
This 823 cylinder head is intended for GM LS rectangular port applications. It is commonly associated with LS3, L92 and similar Gen IV LS engines.
Rectangular port LS heads use matching rectangular port intake manifolds and the correct LS3/L92-style rocker arm setup. They are not a direct match for cathedral port intake manifolds.
These heads are generally best suited for engines with a 4.00 inch bore or larger. Always compare the casting number, port shape, combustion chamber style, valve size, intake manifold style and rocker arm setup with your original engine before ordering.
Suitable For
- GM LS 823 rectangular port cylinder head applications
- LS3, L92, L99, L76, L77, LY6, L96, L94, L9H and similar LS engines
- 6.0L and 6.2L LS-based performance builds
- Naturally aspirated, turbo and supercharged LS combinations
- Cammed street engines and high airflow LS builds
- Stock replacement, repair work and performance LS upgrades
Product Details
- Condition: Used
- Casting number: 823
- Type: LS rectangular port cylinder head
- Application: GM Gen IV LS-based engines with rectangular port cylinder heads
- Common engine applications: LS3, L92, L99, L76, L77, LY6, L96, L94, L9H
- Combustion chamber: Approx. 70cc
- Intake port volume: Approx. 257-280cc depending on source and casting
- Exhaust port volume: Approx. 87-93cc depending on source and casting
- Intake valve size: 2.165 inch
- Exhaust valve size: 1.590 inch
- Port style: Rectangular intake port
- Quantity: Sold each
Typical Stock Flow Numbers
| Valve Lift | Intake Flow | Exhaust Flow |
|---|---|---|
| .100" | 75 cfm | 50 cfm |
| .200" | 163 cfm | 104 cfm |
| .300" | 233 cfm | 145 cfm |
| .400" | 277 cfm | 179 cfm |
| .500" | 317 cfm | 190 cfm |
| .600" | 326 cfm | 202 cfm |
| .700" | 324 cfm | 206 cfm |
This is a used internal engine component and may show normal signs of previous use. The cylinder head is sold as pictured, so please review all images to confirm condition, completeness and any visible defects before ordering.
If you are unsure whether this 823 cylinder head is correct for your engine, compare it with your original part before ordering or contact us for guidance.