Stroker - When you start playing with stroke you have to consider maximum piston speeds. These are averaged to coem up with a mean (average) piston speed, and the stroke and rod length are the variables. The 4" stroke is about 21% longer, but uses the same length rod. That means the piston is accelerated and decelerated a lot faster to cover the longer distance in the same number of crank degrees. Hypers are great pistons. I recommend them and use them a lot myself. But once the expected rpm climbs past about 6K rpm, the stresses on the pin areas of those pistosn begins to hit the maximum safe speeds of the material. Rev them too high, and they will pull apart. There is no set rpm point... It all depends on a few things, but I build mine to stay well within the safety zone, thus any 4" stroked engine gets forged pistons. I have run the Eagle casts before, and one of the two makes a sold 450+hp. But they are not racey parts.
