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Piston rings
are engine parts that seal the combustion chamber, transfer heat from the
piston to the cylinder wall, and help regulate oil consumption. During normal engine operation, only small
amounts of exhaust gases and unburned fuel escape the piston rings and enter
the crankcase. If there are gaps between the piston rings and the cylinder
walls, however, too much "blow-by" can enter the crankcase and overwhelm its
ventilation system. The results range from power loss to engine damage.
"The piston
ring is sort of the poor stepchild of the high-performance engine," explains
Keith Jones of Total Seal, a
Phoenix-based manufacturer of piston ring sets for street and racing engines.
"They get blamed for just about everything." Without the proper fit between the
piston ring and the cylinder bore, however, compression blow-by and oil leakage
can sideline the kinds of car used in IRL, NASCAR, and World of Outlaws events.
High-Performance Surface Preparation
As an
article in the October 2014 issue of Performance
and Hotrod Business magazine explains, Flex-Hone tools from Brush Research
Manufacturing (BRM) can help increase piston ring performance. In "Rings True",
part of the publication's Precision Engine section, automotive writer Ed
Sullivan describes how BRM's flexible hones "allow for the fine-tuning of
cylinder bores", even in engine blocks made of harder metals that can make
piston ring break-in challenging.
BRM Flex-Hone tools feature
abrasive globules that are permanently laminated to flexible nylon filaments,
and a sturdy metal stem that mounts in handheld power tools or CNC machinery. Self-centering,
self-aligning to the bore, and self-compensating for wear, flexible cylinder
hones are ideal for deglazing the walls of cylinders that are not out-of-round,
and for improving the surface finish of bores that have been honed to size already.
Flexible honing tools aren't
designed for heavy-duty material removal, however, nor should they be used for
initial honing, cylinder resizing, or geometry correction (i.e., out-of-round
bores). Instead, use BRM Flex-Hone tools to impart a plateau finish that
optimizes engine lubrication for reduced friction and wear. The crosshatching
that flexible honing imparts provides a uniform series of grooves for excellent
oil retention, and a superior surface finish that supports piston ring seating
and sealing.
Engine Hones
and Cylinder Wall Surface Finishing
BRM's engine
hones are available in 11 different abrasive types and 8 grit sizes. The Flex-Hone
Resource Guide explains how to select and use ball hones, as Flex-Hone tools are
also known. Industry experts such as Keith Jones of Total Seal also provide
insights. As Jones told Performance
and Hotrod Business magazine, "We recommend this type of hone because it works very
well, is easy to use with a hand-held drill motor, and is really foolproof for
someone who is not an experienced machinist."
Michael
Miller, BRM's Vice President of Global Sales, adds that Total Seal "does its
homework" when it comes to choosing specific Flex-Hone tools. The levigated
alumina super-fine abrasive that the engine parts maker recommends "works best
for their piston rings in harder engine block materials." Members of the
automotive aftermarket and performance racing industries are encouraged to contact BRM with questions about flexible cylinder honing. "We provide this type of support all the time", Miller explains.
Author's
Note: This CR4 blog entry originally appeared in BRM's
Flex-Hone Blog.
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Re: How Cylinder Honing Improves Piston Ring Seating
