JE pistons (964 3.8) longevity, what's your experience?

[JKav]

Was pointed to this forum as this is where the brain trust hangs out - appreciate any insight you can share.

I'm looking at a 964 with a 3.8 conversion built ~1.5 yrs ago w/ approx 15k miles of street & some DE use. It has JE pistons & slip fit Mahle cyls.

Consumption and leakdown are good currently according to the owner (a PPI is pending but for now let's say it checks out). I've no experience with JEs on these engines. I have heard that early JEs had some slap issues but this engine does not exhibit this.

My concerns pertain to the ringpacks & general longevity; blowby, oil control, bore wear etc. I'd hate to buy this thing thinking it's good to go and then have to tear into the engine in 20k miles. Do JEs hold up over the long haul in these engines? Or what's a reasonable expectation of life for a JE piston'd 3.8 in your experience? Hard street/DE use, not racing.

Also, is there more than one 'shelf' JE config avail for such 3.8 conversions?

[chris_seven]

Ring Groove wear ?

2618 Alloys not as wear resistant in this area compared to Mahle stock piston.

[aws]

My concern would be with the slip fit 102mm cylinders...not the JE's. They have a reputation of being unstable and cracking around the spigot. I think this is not a problem if they are LN cylinders. Charles uses a rough number of 1.5mm for spigot skirt thickness for his cylinders---that number would be considerably more for Mahle cylinders. In my opinion you would need to refresh the bottom end way before you would have any problems with ring groove wear on the JE's if you are DE'ing the car. I would also be concerned about rods/rod bolts---the stock bolts are a accident waiting to happen.
aws

[EBS_Don]

If the piston set is an "off the shelf" set or set that came through us(Engine Builders Supply/EBS Racing) then it is using genuine Goetze rings which is the original supplier to Porsche. Honestly, we have had tremendous success with JE's over the last 10 years. The only issues I ever see is with guys trying to use worn out cylinders. They have proven to be quiet and the oil control has been excellent when used in cylinders conforming to the proper specifications. As for the 102mm bore/107 spigot cylinders, when used in a non-turbo application we just don't see any problems. If the compression and leakdown numbers are OK then you should be in good shape.

[AlfonsoR]

I was wondering the same, about longevity of JE's. I've been contemplating how many gold molar crowns I have to hock to buy a set of 3.2 to 3.7 JE/Nickies conversion.

I have seen some engine builders say JE's are a good choice for a hot rod engine that might get torn down more frequently, but no one's defined that frequency. As opposed to, if you want a long lasting, daily driver type engine, then Mahle pistons and cylinders are the only way to go?

So an extension of JKav's questionon.... Don @EBS, or other expert engine builders, can you chime in and define Hot rod engine tear down frequency vs what daily driver life expectancy is if both are taken care of with good oil and warm up discipline? Thanks.

[brads911sc]

I think Mahle for street engines is hype by the old timers who also want to sell you a set for 4k -5k or from before the JE's were upgraded to make them more reliable.
I know a 1/2 a dozen people with JE's with well north of 80k miles in several different makes/models and there is no issues... will they last 200k miles? maybe not, but I can buy 3 sets of JE's for the price of one set of Mahle's.. do the math. JE's are just a better buy for anyone driving less than 10k miles a year. They will easily last 12-15 years at which point youd do a top end and have it apart anyway. If your JE's last 12 years its kind of a mute point isnt it? Many of us could drive 20 years and not put 100k miles on a set of JE's. Why would you ever buy Mahle is the real question...

[aws]

I would agree with Don @ EBS that I have seen more turbo than non-turbo failures with the 102mm slip fit cylinders. In a lower HP street configuration you are probably not going to have a problem.
As far as the question about durability I have done a"hard" DFC coating on the skirts--run the skirt/wall down to .0011 to .0013. Used scotch brite to plateau hone the cylinders and had excellent results. I have never anodized the ring lans---JE offers that service if you want it--to me it would be overkill.
In the end if I were going to spend the money that Mahle wants for pistons and cylinders I would be going to JE pistons and LN cylinders--- they are light-years ahead of anything Mahle could offer.
This is coming from a guy who started 40 years ago racing a 2.0 with "Forgetrue" pistons. ---You could hear the piston slap over the megaphones. (until it warmed up)

aws

[brp914]

Originally Posted by aws

In the end if I were going to spend the money that Mahle wants for pistons and cylinders I would be going to JE pistons and LN cylinders--- they are light-years ahead of anything Mahle could offer.
aws

I think you need to qualify that statement. I recently bought some Mahles from a professional builder who builds mostly GT1, GT3, but also occasional air cooled 911 engines. He showed me the Mahle pistons from a GT engine and they were truly exotic. He uses Mahle/Perfect Bore only. Mahle continues to be oem equipment even in domestic cars to this day. So to say that JE/Nickie are "light years ahead" is a stretch. A set of Mahle isn't much more $ than JE/Nickie and has a history of 100 % reliability and quality. I'm glad to hear that JE is catching up and have fixed issues with cyl wall clearance, broken ring lands, and whatever. I'll consider them next time.

[lindy 911]

Interesting note: many NASCAR teams now run Mahle where up until a few years ago most ran JE..

I have JE in my 911 and have used them in brutal blown BBC applications with truly remarkable results. In my opinion they are bulletproof.

[aws]

To say that Mahle has a record "of 100% reliability" just indicates a lack of experience with the product---I have seen my share of Mahle piston and cylinder problems. My main problem with Mahle has been their customer service (non-existent) They are not interested in the air-cooled Porsche market--where JE's business is based with the enthuthiast--Ford-Chevy--or Porsche. Use what you want---but good luck repairing one of their cylinders (they are not weldable) or God forbid--try to get a single piston and cylinder set. I would much rather spend my money with somebody who appreciates it and will give me some service if I need it. The last thing I would say is that under no circumstances should you compare the Mahle cast cylinder to a LN billet cylinder.

aws

[Walt Fricke]

I don't have an iron in this fire, but a couple of years ago a friend had, on two successive builds of a ~3 liter race motor, a piston rip apart at the wrist pin. He's a pretty good wrench. He got rather discouraged by this, as he didn't have many hours on either motor. He felt that J&E was sort of using him as a test bed (not that they were). He switched to Woessner.

I've been happy with the Mahle 90mm RS pistons in my 2.7, and with the J&Es in my 2.8. But this is race motor experience. When I needed a singleton piston, I got one from Andial. But that was 10 or more years ago, so I never tried to deal with Mahle directly.

[JKav]

Oddly enough, the engine in question originally had Mahles when the 3.8 conversion was first done. Very shortly afterward (<1k mi), a rod bearing went south; teardown showed some skirt scuffing too. Seems this second rebuild was when the JEs went in place of the Mahles. It's not clear why. Are the Mahle P/Cs only sold as a set or something?

EBS_Don, I believe this engine has 'shelf' JEs installed Oct2009.

[aws]

Walt: Several years ago I was at High Plains Raceway and had a conversation with a local Porsche mechanic running a RSR clone in SCCA GT-2. He was unhappy with JE with a problem as you described (wrist pin pulling out of the piston) but I recall it was with the 100mm piston He brought up the fact that the forging for the 100mm piston had the same amount of material holding the pin in as the 95mm piston even tho the 100mm piston was considerably heavier--he felt the lack of material was causing the pin to pull out piston at high RPM. As a result I talked to Jerry Roach at JE several weeks later and he admitted that they had changed the forging on the 95/100mm piston---making it heavier and re-enforcing the pin boss. Jerry made the comment (and he handles most of JE's Porsche customers) until then he had really had had no complaints about the reliability of JE's Porsche pistons. I tend to agree--I have built a number of race engines using the 95mm and 100mm pistons---some of those engines going over 100 hours using a 7500 redline with no problems at refresh... Pistons were Zy-glowed with no cracks------I will say I quit reusing the old forgings when refreshing engines--no matter what the hours. Rather than criticize JE here I would tend to say it is testimony of how they respond to customer complaints
aws

[lvporschepilot]

Professional teams are often changing to Mahle due to Mahle's custom piston tooling allowing them to have the flattest ring langs in the business. They are surgical. Pricey, but surgical. Both JE and Mahle use 2618 for their custom work though.

[JKav]

The shelf JEs (for the 964, at least) are 2618. Also, JE redesigned their forging in early '08 to address the limitations of the earlier forging.

For those that have experience with the updated/current shelf JE pistons in these engines, what is typically their life-limiting aspect that dictates teardown interval? Do the slugs simply fatigue quicker than the Mahle shelf stuff, or is it more ringpack-related (loss of compression, oil control), or something else?

[lvporschepilot]

I wish someone would clear this up for me as well as I just don't understand why Mahle = magic to some people. 6 years ago an F40 motor was built with JE pistons and it dyno'd at 634bhp, and this was a street engine that was very streetable. As of last fall and many hard thrashings, the engine remains in brilliant condition. In a racing car where an additional 4bhp might be made due to slightly better ring land sealing then I suppose I could understand wanting Mahle, but even that is conjecture as JE has their ring land technology very nearly down to as close as Mahle. .004 Microns is tight. And both use 2618 and both have tons of experience.