Anybody using pistons other than Mahle in their 930?

[fastfredracing]

I am in the middle of a rebuild of a 930 that was over boosted. It has near perfect cylinders, ( 50K ) , but the pistons have detonation marks all the way down into the second ring land, and the lands are toast.
I always feel real safe with mahle, but understand that a few of you are using J@E's. Any feedback? How many miles on your setup?
Thanks

[timc]

interested to hear responses on this one as well.....

[T77911S]

i would not use JE's. not an expert, but they do not offset the pins like mahle does. i also understand piston slap can be bad, especially when cold.

[Ronnie's.930]

This is an interesting read regarding J&E though it may not apply to the turbo application pistons -

J&E Piston failure

[Midlife930]

I have had great success with JE in track use turbocharged BMW and Porsche.
You must get the clearance correct & then they have survived detonation that would broken ring lands on the cast pistons I have used and broken in the past.

My experience so I continue to use JE

Dave

[sjf911]

I had a set of 98mm JE's that were 10.5:1 and boosted up to 0.7 bar that looked pristine when I swapped out for a set of 8.5:1 JE's but I never ran them past 6600 rpm.

[JFairman]

Originally Posted by Midlife930

I have had great success with JE in track use turbocharged BMW and Porsche.
You must get the clearance correct & then they have survived detonation that would broken ring lands on the cast pistons I have used and broken in the past.

My experience so I continue to use JE

Dave

What you say is good and correct but just so everyone knows the Mahle pistons made for a 930 are not cast aluminum like normally aspirated 911 Mahle pistons and BMW Mahle pistons.. they are forged aluminum and that relates more to the posters origonal question.

And, the Mahle 930 pistons and cylinders fit together better and will also last alot longer in a street engine in most peoples opinion and experience because they are designed for it by a company that worked with Porsche from the beginning to design them as close to perfect for the Porsche air cooled motor.

JE is good choice if you need a custom designed or lower cost piston for an application where there is no Mahle piston available, and it is a compromise.. but they usually work pretty well.

[T77911S]

Originally Posted by JFairman

What you say is good and correct but just so everyone knows the Mahle pistons made for a 930 are not cast aluminum like normally aspirated 911 Mahle pistons and BMW Mahle pistons.. they are forged aluminum and that relates more to the posters origonal question.

And, the Mahle 930 pistons and cylinders fit together better and will also last alot longer in a street engine in most peoples opinion and experience because they are designed for it by a company that worked with Porsche from the beginning to design them as close to perfect for the Porsche air cooled motor.

JE is good choice if you need a custom designed or lower cost piston for an application where there is no Mahle piston available, and it is a compromise.. but they usually work pretty well.

this is what i have heard too. this can be part of the noisy engine when cold.
if it was me i would try to go to a 3.4

[jwasbury]

I have JE pistons in my 3.5 liter build. These were matched up with LN Engineering Nickies Cylinders...ordered through Turbokraft with the same specs they use in their own builds. About 10k miles on the engine so far. I don't notice any piston slap or other unusual noise.

[TurboKraft]

Originally Posted by jwasbury

I have JE pistons in my 3.5 liter build. These were matched up with LN Engineering Nickies Cylinders...ordered through Turbokraft with the same specs they use in their own builds. About 10k miles on the engine so far. I don't notice any piston slap or other unusual noise.

We used a specific skirt coating on your pistons, which pretty much ends the pistons slapping.
Even 102mm pistons are quiet on cold startup when coated.

[M5guy]

I think the more interesting question is 4032 vs 2618.

[Aggie93]

The build receipt from Stephen Kasper has J&E on it. When I called Stephen before I bouight the car I asked him why not Mahle. He said he usually used Mahle and the owner must have requested the J&E, but the owner said he left up everything up to Stephen. So I assume I have J&E since that is what was charged.

I think there is about 10k on the the rebuild. I've been meaning to drive up to your shop for the past year. You want to open it up and take a look?

[fastfredracing]

I'd love to. Any time, I always have time to talk porsches.

[fredmeister]

I had about 4k miles on my 98mm JE pistons and Nickie cylinders in my 3.4 liter engine before a snafu and I had some detonation damage at a track event.
Nothing to do with the pistons causing this, but faulty ignition. The pistons held up surprisingly well considering the damage induced.
Prior to this I heard no piston slap noises and wrist pin bosses look fine even now after the tear down. I had the skirts coated with a friction reducing film similar to what Mahle coats the skirts with.
I am impressed with the machining and durability of the pistons so far but with limited mileage like I said only 4k before an unrelated incident.

Fred

[petri]

Difficult to say which is better. We have tested a great bunch of products in heavy conditions (of boost pressure). When choosing your pistons, you have to cope with the cylinders: as Mahle cylinders don't spread out too wide as they get hot, you have to play with the same aluminum type: Mahle cylinders works great with Mahle pistons (any RUF or other Mahle based pistons do extend with same scale), but like with JE, which are for sure OK pistons, needs coupling cylinders with similar aluminum characteristics, which have same extension rate when getting hot. As simple as that. In NA engines the tops of the pistons doesn't get that hot, the aluminum type isn't so crucial, but with high boost turbos, it is.

[patkeefe]

fastfred, what kind of pistons were broken up in the build you speak of? Were they Mahle?
I have JE special build pistons in my turbo 3.0 SC engine, but I don't run a lot of boost, nor have I run enough miles to make an objective assessment yet. I have Mahle SC cylinders, and the pistons are uncoated, IIRC.