* The 4.6L SOHC (Single Overhead Cam) engine: This was the base engine for the 1999 Expedition. It produced 230 horsepower and 285 lb-ft of torque. This engine is often referred to as the "Triton" engine.
* The 4.6L DOHC (Dual Overhead Cam) engine: This was an optional engine in the 1999 Expedition, mainly found in the Eddie Bauer trim. It was a more powerful and refined version of the SOHC engine, producing 250 horsepower and 305 lb-ft of torque.
Here's a table comparing the two:
| Feature | 4.6L SOHC | 4.6L DOHC |
|---|---|---|
| Cam Configuration | Single Overhead Cam | Dual Overhead Cam |
| Power Output | 230 hp | 250 hp |
| Torque Output | 285 lb-ft | 305 lb-ft |
| Fuel Economy (City/Highway) | 14/19 mpg | 14/19 mpg |
| Availability | Base Engine | Optional (Eddie Bauer Trim) |
Key Differences:
* Cam Configuration: The SOHC engine has a single camshaft per cylinder bank, while the DOHC has two camshafts per cylinder bank. This allows for more precise valve timing and higher power output in the DOHC engine.
* Power and Torque: The DOHC engine produces more horsepower and torque than the SOHC engine.
* Performance: The DOHC engine is generally considered to be more powerful and refined than the SOHC engine.
Note: Both engines used a similar displacement (4.6 liters), and the same bore and stroke dimensions. However, the DOHC engine used lighter pistons, different connecting rods, a higher compression ratio, and a revised intake manifold to achieve its higher power output.
It's important to know which engine you have in your 1999 Expedition as it will affect parts compatibility and performance. The VIN number of your vehicle can be used to determine which engine it has.
