Not the same. Early 911's used cast iron cylinders. More modern 911's used Nikasil on the air-cooled aluminum bore 911's. The 928 and 944 used Alusil. Newer Porsche water cooled engines use Lokasil. It's a newer version of Alusil. The GT2 and GT3's still use Nikasil coated bores.

That is true and it is common knowledge. My 914-6 has Nikasil barrels and Mahle pistons (95mm). However, the only point I was attempting to make was that JE has the experience and technology to provide a piston/ring design which will perform as well as anything on the market. Just my opinion.

The rep I spoke to told me otherwise.
I've just sent 2 sets of pistons and rods, they'll arrive to them this coming Monday. I'll let you know what they say once they have a look at them.

OK, what coating are you going to use? You have to run a coated piston or a coated bore. In an alunminum bore you must use dissimilar metals or the engine will fail very quickly.

Before you waste your money. Call some reputable Mercedes engine builders who do it for a living and see what they use. Try Renntech or Kleeman and see what they say.

The rep asked me what coating is in the bore in order for them to apply the proper coating to the pistons. I'm 90% sure its alusil, which is why they suggested I send them 2 pistons to examine and confirm.

The pistons I'm getting will be fabricated (with the proper coating), they're not off the shelf. I agree with everything your saying, though I'm pretty confident JE will figure this out.

Your concerns are much appreciated, the last thing I want to do is make a costly mistake.

If they can do an iron/ferrocote, that would be perfect. The only one they offer that looks like it might work in the Alusil bore is the KoolKote since it covers the entire piston/cylinder area.

Good luck. Make sure you get the piston to wall clearance correct. With the JE's you will have to run more clearance than the Mahle's because the JE aluminum has a different different expansion coefficient than the Mercedes cylinder. Your clearance will be greater and you could have some piston slap until the engine reaches operating temperature.

I'm usually thrifty and I was when I learned the issue with JE's in the Alusil bore with a non OE piston coating the hard way. In hind site, I'd go with the Mahle's or coat the cylinders in Nikasil. The Mahle's cost much more than the JE's but they will last much longer and you will sleep well at night not worring if your piston to cylinder clearance is correct or if the coating is going to fail and ruin your engine.

There is nothing wrong with JE pistons but they were not made for the Alusil/Lokasil blocks. I wish you the best of luck but don't be surprised if you have an early engine failure.

I absolutely agree that there will be no sleepless nights if you use Mahle. That said, if JE was provided with a sample Mahle piston and I was given their absolute assurance that their product would be compatible with no issues, I would have no problem using JE. However, I would have to have that assurance in writing. Without that assurance, for me, Mahle is the only choice.

After reading your posts I'm begining to second guess my decision. I don't understand why Mahle can manufacture the right piston, and why you guys believe JE cant?

Having my original piston in hand, why wouldn't JE be able to fabricate the right piston with the right coating?

Please explain this as I don't want to regret my decision. Your input is much appreciated.

BlownV8 sent me a great article on this. I did not heed his advice and allowed Vadim to go with custom CP pistons. Engine seized up after a few hundred miles due piston expansion and clearance to wall issues. The entire block was not salvageable so i had to get a brand new E55 short block.

Go with Mahle or Koblenscmidt (sp?). The ONLY SAFE choices.

How is this the piston manufacturers fault? The engine builder must make sure that the piston to wall clearance is large enough to allow for piston expansion before full assembly. I understand that the coating affects, but it's a consideration that should be taken when honing the bore.

Regardless, getting the proper type of piston is without a doubt beneficial...but I wouldn't blame the seized engine on JE.

FWIW, I've used CP,JE and Mahle pistons before in other builds I've done or assisted in and have yet to have an issue. Piston to wall clearance is CRUCIAL. To much and you have clatter/blow-by...to little and your engine will seize.

GT-ER is correct.
Forged pistons have a higher expansion rate, thus the reason they're made slightly smaller than the cast ones.
A reputable manufacturer takes this into consideration when they fabricate a custom application.

I just had mine installed and will be getting the car back this coming week.
I'll let you know how it works out.

It's all in the clearances. Using the right material/coatings will allow for tighter clearances without seizing but most modern piston designs will allow for loose piston to wall clearances with minimal to no piston slap.

Heck, for me piston slap has been a thing of the past with how awesome piston skirts have been as of lately.

I took a couple cell phone pics I took of a piston prior to instalation.
Here you could see the skirt coating we're talking about.

Let us know how the CF hood & fenders work out. That will be a huge weight saving and definite handling improvement.

I am not blaming CP. The engine builder did not spec the tolerance properly as Vadim admitted. My experience just tells me that unless you have an engine builder that did this numerous times, I would just go with the safe route such as Mahle or Kob.

The problem is that it doesn't matter the brand you use...you use a Mahle piston for example and if you do not check for proper clearance then you can still have the same engine disaster.

There is no "safe" way without checking for proper piston to wall clearance. There are only lesser bad ways...lol. Even OEM require to be checked ( though most people probably don't and mostly get away with it since they are definitely going to be the best made-to-fit ).

I usually just go a little over when boring ( the largest piston to wall clearance possible without overdoing it ). The chances of piston slap on a modern design is minimal ( have yet to have one slap ) and the chances of the engine seizing is near zero.

When I rebuilt my block, it was sent to Milenium and nikasil coated.. Then stock piston was sent to Wisco and they made thier armor coated pistons for my block.

The only problem, was that Wiseco did not have the dies to make the rod to piston clearance for factory AMG top driven specs. So, I had to have shims made.. JE owns Wiseco and JE can make the piston for the top drive specs.. If I did it over again, JE would get the nod.. Either way, my build has been rock solid for 25K so far.. Dynos, 1/4 mile and mile racing.. Engine makes great power and my recent compression test was perfect!!!! The forged pistons due burn a little more oil, like a good warm up and love to run hot!

One last thing, Wiseco prefers thier forged pistons to run .030-.035 piston to wall clearnace and it would be nice to get that a little tighter, if one had a choice.. .027 would be nice! JE can do it.

While tighter clearances would be theoretically better, it really won't make much of a difference. Not enough for me to care anyways. Large clearances FTW! LOL.

JE shimmed my pistons as well.
They offered to make me a set of forged rods, but upon receiving my stockers they told me the AMG rods are strong enough.

I hope I have the same luck your having. Getting the car back tomorrow.

A lot of good information in this thread. Thanks for all the feedback guys.

Hey

Anyone got part number for the forged pistons as I am looking to get a set, finding it hard to get them in the UK, any contact numbers and prices would be great as I am building my bottom end on my E55

Thanks acid

The reason why your cyl 8 piston melted is due to a fuel starvation issue. I would call Bruce, owner of TTM and ask him to explain to you why this occurs. He came up with a fuel kit that takes care of this issue. It is my understanding, #8 is the last cylinder to receive fuel, and on modded 55K motors, this is starting to happen more and more.

Exotic-Metal on here, did a engine rebuild with forged JE pistons I believe, but you need to be aware of the special coating of the engine block before you choose a forged piston.

Any idea how much to resleeve the 55 block?

Tech how did the JE pistons work out for you? and did you balance the rotating assembly after, and how much did they charge to make pistons? Sorry so many questions thanks in advance.