JE Piston Ring Thickness
 

Just got the JE 10% off email... had a look at their offerings.
Trying to understand what the difference of thicker or thinner rings is?

The piston with the thinner rings, is more expensive...

Which one should I order?
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I had a set of 98 mm JE pistons with the thinner oil control rings and experienced high oil consumption. I had the pistons cut for the thicker rings and never looked back. Yes, the thinner rings most likely have less drag but at a cost of excess oil use.

that's very interesting...

A well known 911 race engine builder advised that for a normally aspirated race application to use 1 mm top, 1.2 second, and 2.8 or 3 mm oil rings. Looks like the exact specs on the right above.

The price difference is odd if the ring thicknesses are the only difference.

I have a set of #274048 I’m about to install, the skirts are not coated as seen in pic, maybe that’s the difference in price??

The catalog your looking at is wrong, according to J&E the skew number on the higher price pistons are 11.5 compression and have a different dome cc. You want the lower priced ones for a 9:5:1 compression. Here’s the data sheet that came with my pistons.

Not sure how it is wrong, as this is from the JE Piston website. Your SKU number 27048 and your data sheet show you for the thicker rings, exactly as per the JE website states.

So I changed my 'filter' on the JE website and instead of choosing 95mm bore, I selected 3.74inch bore, and a different option appeared. According to the come volume, this would give a compression ratio of 10:1 (which would be ideal for me) assuming a 1mm deck height.
What I dont understand is why they have a different option using inches for the bore instead of mm. It is a different piston altogether. Annoyingly, they do not publish the ring thicknesses to compare.

Apologies for the size of images... I use IMGUR to host them but they seem to be changing how they do things and resizing is really hit and miss...
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Mike, what I was saying is that in your original post you asked what the difference was, I told you the piston on the right with the thinner rings according to my catalog is a 11:5 compression that’s the difference. If you’re building a 3.0 95mm with 9:5:1 you want to order the pistons 274048. I’ll email you the je catalog.

Are you saying that where they list the dome volume od 38.5cc, that this is an error?

In my later post, I found the 3rd option which does sy it has the higher compression, however they dont list anything for rings...

Shoot me a valid email I’ll send you the catalog. Stop worrying about the rings, there’s only 4 stock 95mm domed pistons for a 3.0 and all are different compressions.

I recently had a similar question on two part numbers for 2.7 engine that looked the same. I emaled JE pistons and the response is below.

261663 is a standard design piston at a weight of about 404 grams

353235 is a newer version of that piston with some extra features and underhead milling making it a more desirable lighter design. 368 grams.

Cost for 261663 is 1622.18

Cost for 353235 is 2367.17

john

Creating a good seal in these air cooled engines is and has always been a challenge.
Ever since we started working with JE back in the early 90s (when they needed .007" clearance) ring have been an issue.
We try to avoid the shelve pistons from JE and CP and special order our pistons with Goetze ring packs. It cost more, and take longer but the results are generally positive.
The Goetze oil ring is easier to gap (many 3 piece rings recommend "don't gap" and Nikasil coating seems to prefer the one piece oil ring to control oil consumption. Material properties, coating performance and ring design are decades tested and track proven.
Not going to the track, we seen Goetze rings still performing well way into the 200K range.

I’m using a little higher RA with the JE stock rings than I would with Goetze. Hopefully that will help a little.

never got your catalogue, but JE sent it to me and even they said not to rely on the data on the web!

I’m sorry Mike, just checked my Mail says it was sent last Sunday 12:16 pm est. At least you got it. Let me know if I can answer any questions.
I used an 800 grit brush research hone instead of a red scotchbrite to deglaze,gives you a little higher RA around 7 to 10 with 4 quick strokes in soapy water.

Interesting read. My 1984 911 was built with JE high compression special make pistons. They're high dome, 12.5:1 compression with 22mm rod ends. I had a fuel related issue and ended up melting a hole in one of the pistons, requiring new replacements. When ordering a new set from JE, they suggested the latest improvement would be to order them with the thinner rings. I went with their recommendation and placed the order. The engine did make more power, unfortunately it was short lived. I started to get massive blow-by with about 5 hours on the engine. I did a leak down test and the numbers were bad on all cylinders. Taking the engine apart showed that all the pistons had a large amount of carbon buildup, especially on the oil control rings. Not really having much faith in the JE piston rings, I contacted Total Seal to see what they offered. They told me that they didn't know why JE piston was recommending the narrow piston rings for the air cooled 911 engines. They designed a set of rings that they thought were going to make the pistons work in my application, although it wasn't ideal. It's been 20 hours since I installed them and I'm having a blow-by issue again. Measuring my original JE's pistons with thicker ring widths, the top and middle ring measure .056" (1.4mm) thick, the oil control ring measures .113" (2.87mm). The updated JE piston set spec's out 1mm top, 1.2mm middle, 2.8 oil control ring.
So in my experience, I don't recommend the thinner piston rings. To resolve the issue I'm thinking I should widen the ring grooves and install a new set of piston rings. I like what Henry Schmidt says about the Goetz rings. I've done a quite a few rebuilds over the years and have used their rings. I've never had an issue. I wasn't sure I could use their rings on a track car, but from the sounds of it, I could. Does anyone know if Goetz has an option for my 98mm piston in the above wider widths?

I just installed a set of JE pistons reluctantly. Too many unanswered questions for me.
Ring gap differences, RA, differences, conflicting advice from different people.
I ended up using a slightly higher RA of around 10 to 12 hopefully to help rings seat a little better. I also split the difference on ring gap, I don’t understand why JE doesn’t take expansion of nikasil/ aluminum cylinders into consideration when advising ring gap on these motors. If I had to do it again I’d just spend the extra $$$ and go with mahle and goetze.