[sgcuda]

For what it's worth, longer connecting rods do not make more HP. PERIOD. It doesn't work that way. Longer connecting rods give less angular deflection which results in less rotational friction and allows higher rpm use because of piston acceleration, and longer duration around top dead center during combustion stroke. Since the wrist pin hole is higher, the piston skirts can be shorter which translates to less reciprocating weight. With a longer rod, a piston that has a higher wrist pin location is required to maintain proper deck height and compression. A longer rod does not increase compression or displacement. If the same piston is used as with a short rod, you will have nothing more than increased expenses, when the pistons slam into the cylinder head. Longer rods are preferrable depending on application (higher rpm usage).

[Kyle F]

Wouldn't using a piston made for a long rod on a short rod actually cause a loss of compression because the piston would set lower in the bore and create piston slap at the bottom of the stroke?

[b_chandler]

I guess all those ministock guys and Esslinger engineering got it all wrong then. Wow, and after all these years too.

[sgcuda]

You're missing the point. Look at the Chevy 400 smalblock. It should have had a large 4 bbl or even a dual quad option. But instead it only came as a 2 bbl. Why? Because the short rod (5.565") created such piston acceleration/deceleration issues that the engine wouldn't rpm enough to make use of the jarger cfm flow. All I'm saying is longer rod ratio's allow for more engine potential, but do not , by themselves, create more power.

[Marvin]

Seems to me the accelleration is determined exclusively by the throw (i.e. the stroke) of the crank and the RPM. Regardless of whether the rod is one inch or ten inches, it only moves with the crank rotation.