maximizing piston to bore ring seal



Re: maximizing piston to bore ring seal

Postby Hap » October 6th, 2012, 12:12 pm

Hi Grumpy,

This is my first post here; been a longtime member on the HybridZ website and appreciate all the help you provided members there over the years.

Would like your opinion on piston ring options. I've noticed piston ring manufacturers advertising ring sets that use a plasma moly iron 1st and 2nd ring.
Is there much advantage to using this on a mild street engine vs. the tried and true plasma moly 1st and cast iron 2nd ring.
The basic set up is 355 SBC, forged JE pistons with 1/16" 1/16" 3/16" oilers with 6" rods.

Appreciate any suggestions on this.

Cheers
Hap

 
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Joined: October 6th, 2012, 11:56 am

Re: maximizing piston to bore ring seal

Postby grumpyvette » October 6th, 2012, 1:49 pm

GOOD QUESTION<
OK, first lets talk a bit about what a plasma moly iron piston ring, is, its a standard cast iron ring with a recessed area thats filled with aa comparatively low friction and easily lapped to shape outer surface material during its manufacture, thats embedded in the rings outer contact surface , allowing the piston ring to seat to the cylinder wall quickly and hold a bit more oil in its micro structured surface than a solid cast iron ring would, this reduces wear on the cylinder walls and reduces friction, and speeds up the lapping in process.
these are almost a standard ring design for the last 40 plus years and most engines in cars use them.
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and be aware if the engine over heated a top compression ring, that ring might have expanded enough for the piston ring ends to butt, expand and lock the ring in the bore for an instant, resulting in cracking or deforming the piston groove, if it did the compression ring seal will have been mostly destroyed(PERMANENTLY)
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if the valve train clearances and rings are installed correctly ,cylinder pressure helps ring seal and break-in so don,t be afraid to keep the engine constantly changing rpm and load as this seats both the rings to cylinder walls and throws extra oil mist on the cam lobes, lifters and cylinder walls and maintain enough oil pressure to keep the rockers properly
lubricated
[b]The correct cross-hatch pattern is just as important as the grit used. Most machinists will use some sort of plateau hone for final finish, while leaving the cross-hatch in place. Make sure that both the top compression and the second rings are installed correctly. theres usually a DOT indicating the side to face up. If they are installed upside down, they will actually pump oil to the combustion chamber.

__________________
[/b]
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use of the proper tool helps keep the gap and ring ends square and parallel

BORE SURFACE PREP MATTERS
viewtopic.php?f=51&t=588&p=1665&hilit=honing#p1665
PISTON GROOVE PREP MATTERS
viewtopic.php?f=53&t=5454


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these are generally positive characteristic s IF the engines cylinders are honed with the correct grit (usually a 280 grit hone)as opposed to ( a 220 grit with strait cast iron rings) and honed with a torque plate in place, because the rings will seat faster and seal better and require far less time before they form a good bore to ring face seal, moly faced rings work well in most applications where you have an air filter on the engine and change the oil fairly regularly, theres several dozen different designs and the ring clearances are critical to correct function.
most rings are marked with a DOT on the upper surface,(but not all brands have this, on many you must rely on a careful examination to determine what side faces upwards , most come with instructions)
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failure to get the end gap correct or have the rings correct surface face up will quickly cause problems


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http://www.jegs.com/p/Childs-Albert/Chi ... 4/10002/-1

http://www.jepistons.com/PDFs/TechCorne ... rc2618.pdf

http://www.flatlanderracing.com/mahlerings-01.html

http://www.enginebuildermag.com/Article ... rings.aspx

http://www.circletrack.com/enginetech/c ... for_speed/

http://www.aa1car.com/library/ring_info_speedpro.pdf

http://www.rlengines.com/tech/Common_Ring_Types.pdf

http://underthehood.mahleclevite.com/?p=803

LINKS TO MANUFACTURERS RING RELATED INSTRUCTIONS


http://www.rlengines.com/tech/jerings.pdf

http://www.rlengines.com/tech/perfectcirclerings.pdf

http://www.rlengines.com/tech/speedprorings.pdf
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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