The 828cc engine is older technology derived from when I built closed course racing engines that were re-designed for freestyle with different sleeves and porting.
The 828cc is 85mm bore w/73mm stroke (+5mm) using the stock 61X cylinder core.
The SS 865cc engine is our newest technology with using a OEM stock 68mm crankshaft.
This engine was designed from the ground up using 7 port cylinders, our flat powervalve system,
X Scream custom pistons with a billet cylinder and head construction.
The SS 865 engine makes more power, all across the rpm range including more topend over the 828.
The SS piston package has also been expanded to accommodate more oversize bores, 88mm, 88.5mm, 89mm, 89.5mm and last over at 90mm. This alone makes it a no brain'er with 4 more overbores for the life of the sleeves. We also now offer AV gas domes in addition to the pump gas and race gas domes or custom made to suit customers needs at no charge with the purchase of the top end kit or shortblock.
Because we use our own custom pistons made by Wiseco we were able to achieve a very good balance factor for longevity of the OEM crankshaft.
The complete 88mm piston assembly (everything that goes on the end of the rod) is 5 grams lighter than a stock 701 81mm bore stock assembly.
This has produced a very reliable high power stock stroke engine package without the expenses of a high end stroker crankshaft.