KCS

iTrader: (20)

For the scope of this conversation, the "correct taper" will keep the piston supported at BDC. This is done by keeping the largest diameter ("major OD")high enough in the skirt so that it doesn't fall below the bore at BDC. When the major OD falls below the bore at BDC, the piston to wall clearance increases excessively and the problems mentioned early begin to occur.

I said old and outdated designs. When that article was written, JE was (and probably is) still using 1.5/1.5/3.0mm ring packs in their shelf LS pistons, where other manufacturers were going down as thin as 1.0/1.0/2mm. The major OD in their skirts were lower than other manufacturers as well, not taking into account the thinner ring pack either.

Yes and no. It's kind of complicated with several of these companies being owned by the same parent company now, but in my opinion, JE was not very good in terms of design and Wiseco was probably the best. The guy that wrote the article I posted earlier, used to work at Wiseco and was also a big part of the effort to correct the design flaws of the pistons that were noisy, smoked, and consumed oil. He's at Summit now and I think its safe to say their pistons are top tier as well.

Summitracing

Yes, Brian Nutter is on the Summit Brands product development team here at Summit Racing. He worked at Wiseco for 15 years starting in 1999 and created their LS lineup (amongst others) and has been at Summit for several years now. The Pro LS line is unique and has a slew of design features not offered by any other manufacturer. Crossing the T's and dotting the i's and designed for professional engine builders and machinists. The Ring Land thickness is maxxed out around modern ring packs. The skirt taper is at full O.D. until .525 in. below the oil ring groove. Taper is .004 in. to the bottom of the oil ring groove. Top land is .054 below the bore size and tapers out to the bottom of the third land. This means the skirt is at full diameter when the piston is at BDC and the cylinder length is 5.430 as found in a factory iron block for instance. Aluminum blocks cylinders are slightly longer. Cam has been minimized as well to spread the contact across the entirety of the piston skirt. Lots of other things to talk about, but mostly covered in his article. Please let us know if you have further questions,