there are some graphs on there.
Some "boil it down" comments from the site:
Engine wear and failure issues:
* Rod angularity affects piston side loading. Reducing the maximum rod angle (a) will reduce side loading.
* Reducing piston acceleration from and toward TCD (point of maximum acceleration) reduces tensile loading of the rod.
Engine ignition and breathing issues:
* A piston that dwells at TDC longer allows the air/fuel charge a longer time to burn. This allows less ignition timing for peak power. Less ignition timing is useful because it reduces detonation allowing (slightly) higher compression ratios.
* A piston that dwells at TDC shorter increases the speed of the exhaust gasses during the overlap period. This increases the scavenging effect at low rpm and the engine makes more torque at low RPM.
* Reducing and delaying peak piston velocity allows the intake valves more time to open more to fill the cylinder. This allows a smaller intake running volume (and plenum) and better high RPM breathing.
Effects of a longer Rod
* Less rod angularity reduces wear.
* Lower piston velocity and acceleration reduces tensile loading of the rods.
* Less ignition timing is required which resist detonation.
* Compression can be increased slightly before detonation is a problem.
* Less intake runner volume is required and high rpm breathing is improved.
* Reduces scavenging at low rpm (weaker low RPM power).
* Longer TDC dwell time. (high RPM efficency).
Effects of a shorter Rod
* Increased rod angularity increases wear.
* Increased piston velocity and acceleration increases tensile loading of the rods.
* Increases scavenging at low rpm (increased low RPM power).
* Reduced TDC dwell time. (Reduced high RPM efficiency).
Now, the comparisons they have graphed on the page are comparing a 3.5" stroke and a 5" and 7" rod.
There is also information on going the "stroker motor" route.... its a "double whammy"
I'm still of the feeling: the 4.2L stroke and rod combo has been proven to be a reliable combo in AMC and Jeeps for a LONG TIME. many with 100's of thousands of miles with very little cyl wear (almost all I have seen have died first via Cam or bearings).
The ONLY DIFFERENCE when going to the 4.6/4.7L cheap strokers is piston diameter. The bigger diameter has more skirt surface area (less wear), and most cheap pistons can be found coated (less wear).
I'm going to stand by my view that the "cheap stroker" will perfectly fulfill the needs of any mild to hardcore Jeep enthusiast, and money is better spent dumping it into head porting, intake work, and exhaust manifolds. The short rod stroker will have a better bias towards low RPM torque (at the expense of high RPM torque... which, with a 4500-5500 rpm redline, is almost never seen). I would only chase after the long rodded stroker for a max effort, non-winter driver that will regularly see high RPM, high torque, and/or blower applications.
(I have a forged setup in another motor. forged pistons and cold winters are definitely annoying!)