L8P 6.6L engine: specs, donor vehicles & swap notes
The L8P is a 6.6 L iron-block Aftermarket / OEM engine built 2025–present, rated 523 hp. It came in 1 vehicle application, including Crate engine. Things to know: it is direct-injected (Gen V parts and controller).
| 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 |
| Reluctor | 58x |
Iron/Alum. heads, DI
The L8P specs above are not yet confirmed against GM documents; GM ratings varied by year and vehicle.
Swapping the L8P: what to plan for
- Computer: the L8P is a Gen V direct-injection engine, so it needs a Gen V computer or a Gen V-specific aftermarket kit; Gen III/IV harnesses and computers don't run it. More: LS swap ECU comparison.
Donor vehicles with the L8P
Where to find an L8P at the junkyard: 1 vehicle application below. Confirm it from the RPO sticker in the glovebox or the 8th VIN digit.
| Vehicle | Years |
|---|---|
| Crate engine | 2024–present |