Butler/ Ross Custom Pistons, 421, 4.000 Str.

Enter desired compression ratio. Butler recommends no more than 9.5:1 CR on cast heads and no more than 10.5:1CR on aluminum heads for pump gas.

High performance pistons from any manufacturer are only as good as their designer. BP has spent years of dyno and track testing to develop our current designs. BP stocks several popular pistons by ROSS but we can design a custom piston for any application to fit your needs. Expedited Production/Shipping is available from Ross. Guaranteed to ship in 5 business days.

Due to the volume of Pontiac pistons we order through them, ROSS has now developed dedicated Pontiac forgings for us. Therefore our ROSS pistons feature the lightest weight possible in relation to bore size, and all ROSS pistons are made with 2618 - T61 forging

After many years of working closely together, Butler Performance and ROSS Racing Pistons have developed a new line of Performance Forged Pistons for traditional Pontiac engines base on a new Butler exclusive forging. For years piston forging designs used by performance piston manufacturers have been based off Small or Big Chevy, Ford, etc. When making Pontiac pistons, these companies would typically use a raw forging originally designed for a small block Chevy, being the closest thing to Pontiac bore size, valve spacing and order, etc. This has worked for many years but sometimes resulted in pistons being heavier than needed because the Pontiac designs didn't "fit" the Chevy style forgings perfectly. Now ROSS Racing Pistons has designed a true "Pontiac" forging exclusively for Butler Performance.These pistons are some of the lightest and strongest available, with no special internal milling required to get the reduced weight. These are the latest "strut-style" design, which lends to the reduced weight as well as increased strength. These pistons can also be run at tighter piston to wall clearance so they are great for performance street applications as well as all-out racing.

All ROSS Racing Pistons (since 1985) have been forged from 2618 billet bar stock and have been heat treated and aged to a T61 condition (2618-T61). 2618-T61 is the material that is used when fatigue resistance and durability are of prime importance by all premium racing piston manufacturers. This material has less than 1% silicon particulate content. High silicon content pistons (forged from 4032 or MS75) will not stand up to the most extreme stress placed on many racing pistons. If a crack starts to form in a high silicon piston it will continue until the piston experiences a catastrophic failure. Simply stated, adding sand to the aluminum only makes it more brittle. In the rare instance of a 2618-T61 piston cracking, the crack will continue to an area where the stress is not as great and will then stop. Another advantage of 2618-T61 over the high silicon pistons is the ability to keep its shape under extreme pressure and high RPM's. "Skirt Shrinking" is not a problem with ROSS Racing Pistons.

Custom pistons are not returnable.