RRD M50/S50/M52/S52 Forged Racing Pistons, 138mm Honda Rod

M5X lightweight NA pistons utilizing the Honda B18C connecting rod!

The Honda B18c rod has the exact same big end diameter and width as an S52, but are 138mm long and use a 21mm wrist pin like a euro S50 or s54. By utilizing the 21mm pin and longer rod, we can reduce the reciprocating mass of the piston/pin by reducing the mass of the pin and lowering the compression height. This reduces inertial load. By using the Honda rods we get a much wider selection of quality connecting rods, improved rod stroke ratio, and reduced weight from the smaller pin diameter.

This piston and pin combo is 36 grams lighter than a stock S52 piston yet it actually has thicker ring lands than stock due to the use of a groove lock spacer in the ring groove. Because of this it is designed to handle 500hp in spite of the weight reduction so it would even handle a supercharged combo.

Valve reliefs are also designed to be large enough to accommodate a 280+ degree cam with full VANOS travel. Can be made for any bore and stroke combination and compression ratios from 10:1 to 15:1