TAC Ring Groove Science

PISTONS: POWERFORGED® TAC RING GROOVES
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TYPICAL PISTON
(NON-TAC) DESIGN
P O W E R F O R G E D p i s t o n s . c o m
SPEED-PRO®
POWERFORGED® PISTONS
Piston without TAC ring groove geometry at
operating temp (thermal arching exaggerated)
TAC GROOVE UPTILT
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FEATURING TAC™
RING GROOVE
TECHNOLOGY
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Piston with TAC ring groove
geometry (at operating temp)
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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.
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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.
SPEED-PRO RINGS – FOR EVERY PERFORMANCE DEMAND
HELLFIRE™ RINGS
SPEED-PRO CLAIMER SERIES RINGS
Designed for professional and fast classes of
circle track and drag racing, these rings offer
features that maximize horsepower.
Designed for oval track “claimer” engines,
bracket racers and street performance
applications, these ring sets include a raceproven design and top-ring material options
that suit a variety of applications and budgets.
©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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Piston with TAC ring groove
geometry (cold engine)
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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.
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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.
PRO SERIES RINGS
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PISTONS: POWERFORGED® TAC RING GROOVES
BULLETIN #1011
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Manufactured from a specially hardened and
tempered ductile iron alloy, these rings retain
tension under the most brutal operating
conditions, including engines relying on
mega doses of nitrous, high boost turbos
and superchargers.