I have to agree with BLYKINS,
Some years ago some tech at MIT probably came up with longer rods are better and gave a little bit of technical reasons behind it, ever since your average back yard mechanic and average machine shop will say longer is better. They threw out the old saying more dwell time at TDC, and ever since every one building motors seems to know it like a bible. The truth is its complete bull%$&t. It all depends on what your trying to do. You always hear the famous lines, longer rods have more dwell time at tdc bla bla bla.. I hate hereing this, because people probaly dont even understand what it means, or the physics behind it. For every reason to use a longer rod there are reasons to not use it Longer rods are not better, as shorter rods are not better. I can gaurentee two motors 100% the same one has 6.2" rods and one has 6.0" rods you wont see a difference in HP due to rod length. The differences come into play with matching your products, which is something people seem to have forgotten. Rod length has more effect on things like intake port size and exhaust port size. Nitrous tends to work better with shorter rod ratio's.
A 6.250 vs. 6.00 rod in a 4" stroke is only .06 difference in rod raito. Not to mention no one ever explains that a 6" rod works better with nitrous and supercharging. Or that 6" rods allow you to run a .200" lower top ring on the piston for heat purposes, or the pins being in the
oil ring. There have been stock engines with as low as 1.45 rod ratio's. I am not saying here that shorter is better, but it certainly is not longer is better. There are so many things that rod length has an effect on that need to be accounted for.. There is 100% nothing wrong with a 6" rod with a 4" stroke. I have done it for years, with no ill effects. Like I said im not saying longer is not the way to go. Im saying it onlyworks to a point and more then often people run too long and sacrifice other area's.