L8P 6.6L engine: specs, donor vehicles & swap notes
| Spec | Value |
|---|---|
| RPO | L8P |
| Family | Aftermarket / OEM |
| Years | 2025–present |
| Displacement | 6.6 L / 401 ci |
| Horsepower | 523 hp |
| Torque | 543 lb-ft |
| Bore × stroke | 4.065 × 3.858 in |
| Compression | 10.80:1 |
| Block | iron |
| AFM/DOD | No |
Iron/Alum. heads, DI
Specs from secondary sources; GM ratings varied by year and vehicle.
Donor vehicles with the L8P
Where to find one at the junkyard. Confirm with the RPO sticker in the glovebox or the 8th VIN digit.
| Vehicle | Years |
|---|---|
| Crate engine | 2024–present |
Next steps
- Find a cam for the L8P
- Compare every LS donor engine
- Size injectors and fuel pump
- Swap guides by vehicle
Sources