Engine builders are looking for ways to provide customers a cleaner-burning, longer-lasting engine. Speed-Pro® POWERFORGED® pistons with Thermal Arching Compensation™ (TAC) reduce oil consumption, blow-by and emissions, and extend engine life.

Utilizing predictive engineering and Finite Element Analysis, Federal-Mogul Motorparts engineers accurately predict engine operating conditions and create solutions such as TAC to overcome performance issues.

THERMAL ARCHING COMPENSATION IS DEFINED BY TWO PRIMARY CHARACTERISTICS: 1. Ring groove “uptilt” – Keeping a ring groove perfectly

perpendicular to the cylinder wall is the key to peak efficiency. Thermal expansion at operating temperatures will cause changes in ring groove geometry (also known as thermal arching), resulting in ring tilt. When this occurs, rings are no longer square with the cylinder wall and will not seal as designed. To overcome this, the Speed-Pro® POWERFORGED® piston’s ring grooves are engineered with a slight uptilt – invisible to the naked eye but sufficient to accommodate the thermal arching that occurs at operating temperatures. It keeps the ring square with the wall for more power and reduced oil consumption – better than any other design.

2. Ring groove flatness – Speed-Pro’s CNC groove machining process produces a ring groove of superior flatness with no more than a 15 micron variation (“wave”) between any two points. This assures that the ring will sit in the groove firmly and correctly, maximizing ring seal.

FEATURING TAC™ RING GROOVE TECHNOLOGY

SPEED-PRO® POWERFORGED® PISTONS

SPEED-PRO RINGS – FOR EVERY PERFORMANCE DEMAND

Piston with TAC ring groove geometry (at operating temp)

Piston with TAC ring groove geometry (cold engine)

TAC GROOVE UPTILT

Piston without TAC ring groove geometry at operating temp (thermal arching exaggerated)

TYPICAL PISTON (NON-TAC) DESIGN

BULLETIN #1011

PISTONS: POWERFORGED® TAC RING GROOVESP

IST

ON

S: P

OW

ER

FO

RG

ED

® TA

C RIN

G G

RO

OV

ES

E N G I N E S O L U T I O N SE

NG

IN

E

SO

LU

TI

ON

S

P O W E R F O R G E D p i s t o n s . c o m

©2015 Federal-Mogul Motorparts Corporation. All trademarks shown are owned by Federal-Mogul Corporation, or one or more of its subsidiaries, in one or more countries. All rights reserved. Form #SP131146. Printed in USA.

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