Larry928GTS

I suppose that on the same basis as the BMW argument, an argument could be made against Alusil because of the problems there were with it in the Chevy Vega.

Interestingly enough, I've read the exact opposite as far as cost goes, that the Alusil is what's cheaper than the Nikasil for the manufacturers. I can't imaging NASCAR, Formula One, and Porsche on their factory race cars as well as on the Carerra GT using Nikasil to try to save a little money if Alusil is really better.

According to Mahle on their web page, Nikasil has been doing okay at Le Mans as well.
http://www.us.mahle.com/C125708F0068...FJBP2038MARSEN

There's a little bit of information on some of the various cylinder stuff at www.lnengineering.com/type4.html

Has anyone ever sucessfully gotten custom pistons with the same coating as the stock pistons have, to run in the stock Alusil bore? Discussing them seems like a moot point if they're not available.

FlyingDog

I'd consider wearing out a new street car engine in 30k miles major. I don't think the Mercedes problem was related to fuels, it was a design/production issue.

This probably won't be a problem as many people have used Nikasil on custom motors, just something to consider in the Mahle/Alusil vs JE/Nikasil debate. As John Kuhn pointed out, Swain now offers an Alusil friendly coating. So, JE/Swain/Alusil is another option.

FlyingDog

It's the same as saying Nikasil is the way to go since it is used in Carrera GTs. Porsche (or more likely Mahle does it for Porsche) is not going to plate the block for Mark. I would expect BMW to do a better, more consistant job than US Chrome, yet they had a large number of failures.

People who aren't selling only Nikasil seem to disagree on which is more expensive and why it's used or not used. BMW has always used Alusil on their V12s, but chose Nikasil on the cheaper V8s. KS seems to think Alusil is more expensive than Nikasil/Galnikal. They should know, they make them both...
http://www.bmwseven.com/Alum_engine....%20galnikal%22

Larry928GTS

I've heard of two or three custom pistons with different coatings being tried in the stock Ausil bore of a 928 engine and scuffing resulting. At least one set was from Mahle, and at least one was from Kolbenschmidt. I've heard of several 928 engines that were still sucessfully running with Nikasil. Basically I have three questions:

#1) Has anyone gotten a set of custom pistons with the same coating as the stock pistons to run in the stock Alusil bore of a 928 engine?

#2) Has anyone gotten a set of custom pistons with any kind of coating that ran sucessfully for any length of time in a stock 928 engine's Alusil bore?

#3) Has anyone that's currently using Nikasil on a 928 engine, or that's used it on one in the past, had a failure as a result of it?

As far as I've heard so far, the answer to all three of those questions so far is "no". I think quite a few peoplpe on this board would be interested in any firsthand information anyone has that can annswer "yes' to any one of these three questions.

FlyingDog

Maybe check with 911 and BMW owners. I'm sure they've tried more combinations than 928 owners.

hacker-pschorr

Matt,
1. Alusil is NOT a coating - it's what the engine is made out of. When you coat a 928 engine it's still 100% alusil covered in Nakisil. As for Mercedes, BMW, Jaguar etc.... doing a "better" job than US Chrome - I know a few engine builders who squeeze 800+ hp out of pushrod engines who would beg to differ.

2. As for asking the "911 crowd" we already did. Todd (man behind the curtain here) started with air cooled VW / Porsche motors (ok, maybe not, he started with Harley motors in the 70’s). His current motorcycle has a type 4 VW engine pushing out 400+hp - it's his daily driver for the past 20 or so years.

Matt, I appreciate your opinion and concern for Mark’s motor, so please do not get the impression I’m trying to pick a fight or anything. I’m here to sort of represent Todd since right now he is in the garage working on a 7 liter 928 motor & the final design on his 5.5 liter “Peoples Motor”.

mark kibort

So, what is the type of coating to be used on a custom piston? Sounds like Todd with the pistons, and will be involved and doing a nicasil plating at "us chrome".

What is wrong with the Alusil and JE's with the proper coating on the piston?

Now, my concern with the block would be with those steel inserts. what about their heat disapating capabilities?

Next would be , what is the thickness of that machined area( and how did they machine that out?) is there enough meat of the cylinders left to bore to 104mm ( 2mm material removed)?

Mk
\

hacker-pschorr

I'm assuming so at this point.
As far as we know - JE doesn't make an Alusil friendly piston.
Todd has not found any heat related issues with this setup.
I'll find out tomorrow.

FlyingDog

Naw, really? Next you're going to tell me it's made of Reynolds 390.

I know you're not trying to pick a fight. I think Alusil and KS or Mahle pistons is the better solution because it is less expensive, less intensive for changes, less potentially destructive if anything goes wrong, the way it was done originally, and due to the fact that Porsche chose it over the less expensive Nikasil process they probably thought it was better. The KS file I linked and others I've seen imply that Alusil is the better solution. I think the only reason Porsche currently uses Nikasil is because it's cheaper. One could claim that they say this because KS developed Alusil and Mahle developed Nikasil, but both companies make both products and have sold both products to Porsche and BMW.

BTW, what about Lokasil?

FlyingDog

I think he's refering to having Swain coat them.

hacker-pschorr

Sorry, many people do think it is a coating like Nakasil, just felt like clearing that up
For starters, Todd spend hours on the phone with the Mahle engineers - what we ended up with was a piston that was not very happy with the alusil. None of us feel like going through that again.

968 pistons would work if Mark wanted to have new rods made.

Well, my dogs name is Loki........... should I chrome my dog?

hacker-pschorr

Ah, gotcha.

If Mark wants to go that route, it's up to him. Tim and Todd have spent a lot of time talking about "what to do" with the three motors that came out of this project after the piston coating issues was discovered. Plating it so far has been the leading option.

FlyingDog

Only if he needs a higher silicon content.

FlyingDog

Are any of the 3 running?

hacker-pschorr

Engine #1 was in Todd's motor - it ran fine but there are signs of abnormal wear on the cylinders. This is the motor Todd discovered a stroked supercharged motor has Tractor levels of low end torque.
Engine #2 (this one) is assembled, never installed
Engine #3 is still in boxes......tempting me. Would make a fun 16V