Re: Bore/Stroke Ratios

Posted by Craig Hendrickson On 2014/2/24 15:12:24

The columns labeled "B/S ratio" should be "S/B ratio" since these are all under-square engines (stroke larger than bore), but otherwise an interesting data listing.

Most modern V-8s are over-square design with a few notable exceptions (Pontiac 455 for example). This has to do with superior breathing due to the overhead valve arrangement where a larger bore unshrouds the edges of the valves. In a flat head (L-head, F-head etc, the smaller bore is more appropriate and compatible.

Longer stroke means more low RPM torque because of the greater lever arm of the crankshaft. An obviously important factor in moving a heavy vehicle from start, but clearly not as a good a "feature" today with the common high freeway speeds.

Craig