One thing people are forgetting, the piston acceleration and speed of an airplane engine doing 2700 RPM is like a small block doing 9K plus rpms, I read the math once on piston acceleration and speed, the huge radials had massive piston speeds, as much as a small block mopar that is maxed out. They also run at a much higher loading, my airplane usually runs at 80-90% power in cruise...a car on the street is maybe 35%...its all in the BTUs when it comes to engine load. Tim