Long Rod vs Short Rod

[Jim Kueneman]

Engine Masters just did a very nice job on comparing long vs short rod on the latest episode (Chevy BB). Final analysis is the long rod was very insensitive to the timing for max power +/- 2 degrees gave the same number. The short rod needed about 4 degrees more advance than the long rod to make max power. The overall torque and HP curves were virtually identical. It seams the only real advantage the piston dwelling at TDC longer allowing longer to burn to maybe help with pinging and insensitivity to timing.

 

[/6 Matt]

All true but in a slant six the advantage of the long rod lies in the fact that it enables you to use a modern lightweight piston.

 

[Jim Kueneman]

All true but in a slant six the advantage of the long rod lies in the fact that it enables you to use a modern lightweight piston.

Good point and they discussed that a bit too as well as other other things that shorting the compression height could do, good and bad. Gets into dynamic vs steady state HP and torque.