[gunslinger]

One advantage that a 2-valve "Pushrod" or "OHV" engine has is the ability to induce more mixture swirl of the incoming combustion charge, resulting in a more homogeneous mix. This allows for more low end torque, when air is not moving quite as fast.

The OHC does allow for more airflow with the same size bore, but this is generally accomplished at a higher RPM because the larger runner size does not keep the velocity of the incoming air at a high enough speed, where as the single, smaller runner on the OHV does.

Also, less moving parts and a lower center of gravity. The above mentioned shortcomings of the OHV can be overcome with extensive port testing as is found in the GenIII and Gen IV General Motors V8's.

There have been whole scientific articles devoted to this topic, and trust me GM would not be using the Pushrod design if it was an "old" (actually OHV is newer than OHC) outdated design. When the LS6 (GenIII V8) was put in a 3100 LBS Corvette ZO6, 30 MPG was attainable while still having 405 HP and world class acceleration and top speed...

Can you tell I love GM's motors?