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Registered User
Join Date: Mar 2014
Posts: 29
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JE ring end gaps too large?
new JE 98mm pistons with their rings ready to go in my 1983 SC motor. Car will be used for the street and DE, not racing.
Their guidelines show .0045 x bore = .0174" minimum end gap for the top ring, but I suspected this was for big cast iron block engines so I called them. They said I could use .015" for my air cooled. Porsche specs show .008" minimum gap. I am still using the same basic jugs (bored 95 to 98mm), but shouldn't the gaps depend on the ring and cylinder material and configuration, which really can't be much different? Why would the aftermarket ring gaps be expected to close up so much more than what Porsche thinks? I don't want to seize my engine, but I do want as much compression as I can get safely. Any thoughts or experience on these ring gaps? Thanks. |
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04-02-2014, 11:50 AM
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That is the same recommendation that I got for mine (0.017" on a 98mm jug).
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Steve Sapere aude 1983 3.4L 911SC turbo. Sold |
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04-02-2014, 01:37 PM
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If you are looking for the best compression/leakdown numbers you can get with the pistons you have....why not look into Total-Seal rings?
I believe the standard placement is in the second compression ring position. Bob
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Bob Hutson |
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04-02-2014, 04:11 PM
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Join Date: Nov 2010
Location: San Jose, CA
Posts: 53
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Better to go bigger . . . won't hurt.
I run 0.012 - 0.016 in my 2.7 (90mm) race motor. Never any problem. Dave |
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04-02-2014, 04:19 PM
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Join Date: Oct 2003
Location: Central Fla
Posts: 1,864
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end gap
You need to follow the formula from JE based on your engine build, we have tested and found no power difference, the problem will be if at temp the rings butt when the gaps are too tight.
Mike Bruns
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The two most useless things to a driver are the braking distance behind you and nine-tenths of a second ago. |
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04-02-2014, 04:54 PM
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Join Date: Mar 2014
Posts: 29
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Many thanks for the replies. I know a larger gap is safer but I'm like the kid who always asks why so I can understand.
With a minimum gap twice what the factory says, while using the same basic cylinders, it threw a red flag. I try to pay attention to those flags rather than follow blindly. The guy I talked to at JE did not instill confidence. Always thought I would try the Total Seal sometime, but I want to limit my variables and use the rings JE provided. If Mike and Dave say that a larger gap doesn't make any difference in power, then I feel better. I will go for .015" which is at the high end of Porsche's range and move on. Rick |
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04-03-2014, 05:21 AM
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1983 Porsche 911SC
Harley
