L78 6.6L engine: specs, donor vehicles & swap notes
| Spec | Value |
|---|---|
| RPO | L78 |
| Family | Generation VI |
| Years | 2027- present |
| Displacement | 6.6 L / 401 ci |
| Horsepower | 481 hp |
| Torque | 501 lb-ft |
| Bore × stroke | 4.065 × 3.858 in |
| Compression | Not yet published |
| AFM/DOD | No |
Specs from secondary sources; GM ratings varied by year and vehicle.
Donor vehicles with the L78
Where to find one at the junkyard. Confirm with the RPO sticker in the glovebox or the 8th VIN digit.
| Vehicle | Years |
|---|---|
| Chevrolet Silverado/GMC Sierra 1500 | 2027–present |
Next steps
- Find a cam for the L78
- Compare every LS donor engine
- Size injectors and fuel pump
- Swap guides by vehicle
Sources