Piston Choices
 

Pretty much most of the aftermarket pistons used in rebuilt engines on this forum seem to be JE's. Are JE's the perfect replacement for mahle originals or are there downsides to these pistons? Ive heard piston slap mentioned quite a few times regarding JE's is this much of an issue? What other options is there when re-using mahle barrels? Anyone used wossner?

Steve

The problem with most aftermarket pistons is they don't fit snugly enough in the cylinder. JE seems to have the best reputation of the aftermarket. Personnally I'd use new Mahle, used Mahle, used Kolben Schmit (alusil) and JE in that order for a street car where long life and quiet operation are most important. There are often used sets on pelican with minimal wear.

-Andy

Hello, Steve.

the difference is twofold: first the alloy.
40 series has more silicon..less expansion.

Mahle and one or two other German suppliers use this.

JE and alsmost all others use 30 series..

Kind regards
David

Well My JE's make no warm up slap noise but I am using qsc cylinders

Steve,

There is no piston & cylinder combination better than Mahle forged pistons and Nikasil cylinders – period. Expensive and worth every penny.

Unless you are building an engine for only a few thousand miles, I wouldn’t choose other. Yes, there are race circumstances where the special pistons from JE and other are appropriate. Yes, there are some non-standard configurations where (unfortunately) a Mahle isn’t possible.

Any engine I would build would be around Mahle Nikasil P&Cs.

The reasons are superior piston strength, low friction, best ring sealing, best cooling and (most important) multi 100K mile longevity. I suspect every set can last 500K miles with proper maintenance. I wouldn’t be surprised at 1M.

Another aspect is POWER. There is a performance reason that Porsche developed these for the race cars. Is it any surprise that all Porsche race engines use this technology. It is all about cylinder sealing and friction.

You may note this is the strongest I say about anything Porsche. I am very unequivocal about this. I think you will find this true throughout the Porsche community.

Best,
Grady

I would agree with that a mahle piston in a mahle cylinder is a matched pair and a proven one at that, with decades and probably thousands of millions of miles accumulated to back your stance.

I would have to say that a JE Piston can be made to work and last; in our case, we designed a cylinder alloy around the expansion characteristics of the 2618 forging alloy that JE uses rather than their 4032 alloy, which is closer to what Mahle uses for their pistons (which in their case is better for them, since mahle cylinders have a relatively high silicon content in their casting alloy = lower expansion, versus our cylinders).

I do have many hundreds upon hundreds of people running JE's in Nickies without any problem (and many other brands of pistons too, including Mahle), and may just now tipping over 100,000 on many engines.

Many people still run OE Porsche rings (Goetze) in a JE Piston and I sell them that way most of the time. I do believe there are far superior rings available in the motorcycle arena that are light years ahead of what is old technology in my opinion, and have been using those modern ringsets for well over 5 years now.

To this date, I have not had a single JE failure, and we do push the evelope in many applications with our product. When two products are engineered to work with each other properly, the solution can be a long lived and reliable one.

Another observation I have made are that most oems are now coating their piston skirts, and that is something the Mahle sets have in common, since they come with a phosphate coating. In my studying how anti-wear additives work, I found one technical paper that hinted towards how the AW film bonds to the silicon peaks on aluminum surfaces (piston skirts) and the silicon is very brittle, so the peak breaks and then empregnates itself into the piston skirt - and the process repeats. Without the coating, scuffing would occur at a higher rate than otherwise with a non-coated piston. I would love to see how the fact that the 2618 forging does not have any silicon whatsoever and how that relates to piston wear.