JE pistons: Questions on durability.

[Gunter]

Couple years back I sent EBS a set of 98mm Mahle cylinders and had them custom-order JE pistons 9.8 CR for CIS.
Ended up building a SS 3.2 with 964-cams and a re-curved distributor by Steve Weiner.
It went better than expected; uses no oil, no leaks and runs like a bat out of hell.
I use 94 Octane; just street-driving.
Very nice performans so far with ~15K Miles.
Charles matches his "Nickies" with JE pistons.
Some people are negative on JE's.
What's wrong with JE's??
Exactly what bad experience did anyone have?
Details much appreciated.
Thx.

[mb911]

I have 98mm JE's in my car no smoke at start up and runs well. Only have about 6,000 miles on them and the QSC cylinders but happy so far

[jess p]

They look great BUT I've heard from many that they are junk after 20,000 miles
and one of those comments is from a very reputable porsche shop!

[Shoepop]

I also heard the 20K figure from a reputable 911 engine builder.

[cgarr]

Over 20K on my 912 with J&E's and they have been hard miles.

[cmcfaul]

So, what goes wrong with the J&E's over 20K mi?

I have them in my 2.4 with over 20k on them. Seem like they are working. A little smoke at startup which I attribuite to valve guides.

Chris
73 911e

[Gunter]

I am hoping for some concrete, first-hand experience with details on exactly what happened with a break-down not just: "Someone told me", or: "I've heard they're junk".

What cylinders? Type? Size?
CR?
Carbs or CIS?
Mileage?

With ~15k so far, I am very happy; no smoke and great performance.
Am I on borrowed time?

[Quicksilver]

I had JE pistons in an Olds 215cid aluminum V8 and they had no real wear after about 38K miles. The skirt finish on them was a work of art. I have never seen the Porsche JE pistons though.

[mca]

Gunter -

Great question.

I am putting JEs in an engine I am currently rebuilding.

Like you, I hope we get some concrete evidence supporting claims that they lack durability.

Wilke3169 put some in his SC a few years back. I think he recently passed the 20k mile mark. He takes it to the track regulary.

Cheers,
Craig

[barney911rs]

I have a friend back in Orlando that uses nothing but JE pistons in his and his customers race motors.

[Mahler9th]

I know of specific issues with 98 mm JE's and other sizes as well, but the issues are/were in racing applications. I know the guys at EBS and if I had a question, one way or another I'd start by talinking with them and Charles at LN ENgineering. I know of local builders that will not use JE's and some that will only use certain sizes. But these are racing situations, not street driving situations.

[Mysterytrain]

Gunter and I have talked about this in the past. I have also had some conversations with Steve Weiner on JE's and Mahle. I hope that I'm not misquoting him here and if so I will edit this posting.
I had a 3.2 SS built for me by a very well known shop here in NJ. We used JE's and a set of custom made billet jugs that were nikasil plated by Mahle [or whoever plates for them]. The engine was great but suffered from smokey start -ups hot or cold. It was frankly embarassing. My mechanic was as unhappy with the results as I was and worked with me to rectify the issue. We tore the engine down and proceeded to re-check everything. I once had some numbers to share but unfortunately I can't seem to find my notes.
I made lots of phone calls while the engine was in pieces and asked lots of questions in search of second opinions. When I spoke with Steve he told me that he recommends that his customers use JE's for track cars and Mahle for street cars. Mahle being the choice for a motor that was expected to last as long as the factory build.
When all was said and done I bought a new set of Mahle, max mortiz from Andial. I have zero smoking issues and I'm thrilled with the engine. I'm not sure if the issue was the JE's or the cylinders or perhaps the combination of the two. My mechanic insisted that he never had issues with these cylinders and mahle pistons. I trust this guy completely. I'm not aware of any differences in shape or taper between the pistons but there appears to be a difference in materials and expansion rates. I know I'm not providing scientific facts as requested but my experience might explain why Charles gets anal with his Nikkies and Henry does the same with the QSC's.
78 9.8:1 Stock CIS, 964 cams, SSI's, Dansk 2 in/1 out

[fintstone]

Supertec put JEs with Mahles in a hopped-up 3.0 about 5 years ago. No problems so far.

[SXSMAN]

We've ( our shop ) has used JE pistons in rebuilds in the past with no problems . That said we now use C P pistons . From what I understand one of the founders of JE didn't like the direction they were going and started his own company .

The pistons are a work of art .

http://www.cppistons.com/about_us/

They've gone into a number of Lambo engines with great results . But the miles aren't there to tell how long they'll last . And none have been put into Porsche engines .

Just something else to throw into the mix .

SxS

[obrut]

i've seen 2 failures of 10.5:1 JE's, both in (different) 2.7 motors.

identical failures, broken top ring land near the valve pocket. both low mile engines, well tuned and serviced.

[JeremyD]

On the 98mm 9.8 to one there have been some wrist pin area failures with the JE's - My wrench showed me one when I was getting mine rebuilt.

I know JE was looking into this failure and they sent the pieces back.

With the mahles bored out using JE's you really have to watch your tolerances - the cylinder can be in spec and because of the different expansion rates of the mahles jugs and JE pistons you can get a little piston slap or blow buy until you are up to operating temp.

That said - the JE's I had measured out almost identical to each other - they were lighter than the same sized mahles - and they were closer in weight to each other than the mahles.

[kenikh]

I talked to Charles about JEs in Nickies and this seems to be a bulltproof combo. The alloys are perfectly matched, so the issues that can exist with Biral cylinders in the past don't happen (piston slap, etc). He said that Nickies and JEs have shown lifetimes similar to Mahle pistons in Mahle Nikasil cylinders.

I think JE has also solved the Biral issue by offering two different alloys depending on the cylinder application. As long as you are buying from a reputable shop, you should have no issues. I was comfortable enough with this explanantion that I have Supertec designed JEs going into Nickie cylinders for a motor build that is currently ongoing.

As far as the 98mm pistons go, I recall that JE redesigned their pistons this year to ensure the breakage issues of the past don't happen.

[kenikh]

On another note, I don't think I will ever build a 10.5:1 engine for the reasons obrut mentioned. I was at Steve Weiner's last weekend and he feels taht even with twin plugs, 10.5:1 is just too much on today's piss poor gas. Plus, if you meticulously cc the old "10.3:1" Mahle P/C combos like the 906 and ST P/Cs, they actually come in under 10:1, while the 10.5:1 JEs come in at a true 10.5:1.

This variance in expectation and the fact that these motors are so timing sensitive can definitely lead to detontation related failure of the type obrut mentioned. At the end of the day, I took Steve and Henry's advice: 9.5:1 JEs and twin plugs means a perfect ignition curve and guaranteed long life.

[Craig 930 RS]

Mahle over JE - every day anytime.
Mahle just do not have the multiple issues........

[kenikh]

Originally Posted by Craig 930 RS

Mahle over JE - every day anytime.
Mahle just do not have the multiple issues........

Oh yeah, Steve agreed on this point, too. The bottom line is that you just can't get Mahle pistons in custom applications, so your decision is typically made for you:

Stock = Mahle
Modified = JE