1. Valve Train:
- OHV: The OHV design has the valves located in the engine block, and they are actuated by pushrods and rocker arms.
- SOHC: The SOHC design has a single camshaft located in the cylinder head, which directly actuates the valves.
2. Timing Belt/Chain:
- OHV: OHV engines typically use a timing chain to synchronize the movement of the crankshaft and camshaft.
- SOHC: SOHC engines use a timing belt or chain, but since the camshaft is located in the cylinder head, the timing mechanism is more compact.
3. Complexity and Maintenance:
- OHV: OHV engines have a simpler design with fewer moving parts, making them easier to maintain and repair.
- SOHC: SOHC engines have a more complex design, and maintenance tasks such as replacing the timing belt or chain can be more involved.
4. Fuel Efficiency and Performance:
- OHV: OHV engines are generally considered to be less fuel-efficient compared to SOHC engines.
- SOHC: SOHC engines can provide better fuel efficiency and offer improved performance due to more precise valve timing.
5. Noise:
- OHV: OHV engines tend to be noisier than SOHC engines due to the additional mechanical components involved in actuating the valves.
- SOHC: SOHC engines are generally quieter due to the reduced number of moving parts.
6. Availability and Production Dates:
- OHV: Ford produced OHV 4.0L V6 engines in the Explorer from 1991 to 2001.
- SOHC: Ford introduced SOHC 4.0L V6 engines in the Explorer in 2002 and continued using them until 2010.
In terms of which one is better, it depends on various factors and personal preferences. OHV engines are simpler, easier to maintain, and may be more affordable to repair. However, SOHC engines offer improved fuel efficiency, better performance, and quieter operation. Ultimately, the choice between an OHV and SOHC engine depends on the specific requirements and preferences of the driver.
