MAHLE Motorsport has recently released a new line of PowerPak piston kits to comply with the 2022 USRA Factory Stock rules for 23-degree small-block Chevrolet engine combinations. The engineers at MAHLE are constantly striving to stay on top of different sanctioning bodies’ rulesets and ensure they make a product that keeps racers legal.
Per the new-for-2022 rulebook:
2022 USRA FACTORY STOCK RULES; ARTICLE 13: ENGINE; §13.1.2
Only standard weight cast or forged (minimum 450 grams) four (4) equal valve relief flat top or dished
pistons are permitted. Must use standard weight wrist pins (minimum 130 grams). Must use minimum
1.5mm, 1.5mm, 3mm piston rings. Maximum six one hundredths (0.06) inch oversized permitted.
Forged from 4032-alloy aluminum, MAHLE’s new USRA Factory Stock pistons have the requisite four symmetrical valve reliefs and are a slipper-skirt design that is both lightweight and stable, preferable for racing applications. Each piston has precision CNC machined pin bores with straight side reliefs in the pin bores for more accessible wrist pin lubrication. The ring grooves in all Power Pak pistons are an area of heavy focus, as the flatter, more precise a ring groove, the better the ring can seal.
Each USRA-approved piston kit includes a 1.5, 1.5, 3.0mm file fit performance ring set and heavy-duty steel wrist pins. These PowerPak piston kits are available for 357, 359, 361, and 362 cubic-inch engine combinations, and are coated with MAHLE’s distinct Phosphate dry lubricant as well as the company’s Grafal skirt coating, to reduce friction in the bore. By reducing friction, heat in the piston is reduced, lessening the chances of wrist-pin galling and micro-welding.
While the Factory Stock rulebook is meant to limit piston selection, MAHLE makes it possible to get a significant amount of innovation and technology in your piston for an edge over the competition, while still conforming to the rulebook.