Some common problems with Flathead V8 crane motors include poor gas flow, low compression ratio and poor combustion chamber shape. These problems lead to low power output.
The side-valve layout forces intake and exhaust gases to flow through a tortuous route, with poor breathing or little volumetric efficiency. The engine tends to overheat since exhaust gases follow a complicated path. Side-valve engines operate safely at high speed, but the volumetric efficiency deteriorates swiftly; thus, high power output is not possible at speed.
A T-head engine is an improvement of the Flathead. It has crossflow layout, so exhaust gases and intake flows in the opposite directions, increasing the motor efficiency.