Nikasil and Alusil

moneymanager · 01-23-2009, 03:19 PM

Am reading your book Wayne. Excellent. I should have gotten it a couple of years ago!
A question: you point out that the factory mixed Alusil and Nikasil pistons and cylinders in the mid 70's. Is it possible to determine reliably which I might have before pulling the engine? Might the magnet test work under the car? Or is there a possibility that one of the cylinder markings might be visible from underneath (or anywhere else?) Thanks,

ZOA NOM · ZOA NOM's Garage

There are exactly 11 heat fins on the Nikasils, while the Alusils have exactly ten. You can put the car on a lift, or simply jack it up high enough to crawl under and find a spot where you can count them on the bottom of the motor.

moneymanager · 01-23-2009, 03:36 PM

Really? It's even easier than I thought. Thanks!

ZOA NOM · ZOA NOM's Garage

It took me a few minutes, but I pulled a Nikasil from my race car, and an Alusil from my Daily Driver and took a pic for you.

moneymanager · 01-23-2009, 04:16 PM

Gosh. It would have taken me at least an hour to do all that. And you got them pretty clean too. Thanks again.

cgarr · cgarr's Garage

Here is a Nikasil and an Alusil, Which one is which?

Henry Schmidt · Henry Schmidt's Garage

The one on the right with the fin support is the Alusil.

cgarr · cgarr's Garage

Yep, (the support!)

ZOA NOM · ZOA NOM's Garage

So, why does my Nikasil have the fin support? Am I missing something?

Henry Schmidt · Henry Schmidt's Garage

Quote:

Originally Posted by ZOA NOM

So, why does my Nikasil have the fin support? Am I missing something?

The cylinders you posted are 95 mm and the cylinders posted by cgarr are 90mm.
Mahle decided that the fin supports first offered by KS were a good idea and copied the design.

ZOA NOM · ZOA NOM's Garage

Oh, thanks Henry. *Whew*

moneymanager · 01-23-2009, 08:48 PM

But aren't we looking at an Alusil with 11 fins AND a Nikasil with the same number? I'm confused.

Eagledriver · 01-23-2009, 09:22 PM

It looks like your 90mm cylinders could have 11 fins with Alusil or Nikasil. I don't know if the fin support is difinitive for your car or not. Notice in the pictures that the cylinders have a distinctly different look to them. The Alusil has a shiny finish almost like someone sprayed clear paint on them. The Nikasil has a standard dull aluminum look. Of course it's easier to tell when looking at them togther but you should be able to tell by this finish. The Alusil basically has glass crystals in it and the material goes all the way through. The Nikasil just has a thin coating on the inside of the cylinder. The outside is just aluminum.

-Andy

ZOA NOM · ZOA NOM's Garage

Yeah, I'm sorry moneymanager, I should have noticed the difference in the years of our cars. I think my assertion about the number of fins is consistent for the Carreras, but I don't know about other years.

tom1394racing · 01-24-2009, 04:02 AM

For the mid 70's motors, 90 mm bore/2.7 liters, the factory used (3) types of cylinders. These were:

1. Mahle Alusil
2. Kobelschmidt (KS) Alusil
3. Mahle Nikasil

The pics below show that all had 11 fins and the only KS had the rib. If we are talking about 2.7 motors, the Mahle Alusil and Mahle Nikasil are almost identical in appearance from the outside. The only way I know to tell the difference is to look at the appearance of the inner bore. The Alusil will have the matte grey appearance while the Nikasil will normally be more shiny or chrome-like. The definitive test is whether the inner bore attracts a magnet indicating Nikasil.

The 90mm/2,7 liter cylinder pics below show from left to right, Mahle Alusil, KS Alusil and Mahle Nikasil.

tom1394racing · 01-24-2009, 05:04 AM

On the 95mm 3.0 SC cylinders, there were also 3 variants:

1. Kobelschmidt (KS) Alusil with rib/10 fins
2. Mahle Nikasil with rib/11 fins (late SC)
3. Mahle Nikasil without rib/11fins (early SC)

All KS cylinders have the rib and have 10 fins. Mahle adopted the rib later in the SC production run and carried the rib over to the 3.2 95mm cylinders. All 95mm SC Mahle cylinders have 11 fins.

So....On an SC it is possible to tell the difference between Alusil and Nikasil by counting the fins, but not by the presence of the rib.

The pics show left to right. KS Alusil, Mahle Nikasil late with rib and Mahle Nikasil early no rib. Ignore the moon cuts at the base of the cylinder on the early SC (it is a non factory performance modification).

moneymanager · 01-24-2009, 06:42 AM

So I think the long and short of it is you need to pull the motor apart and do the magnet test on the inner bore to know what you've got. I was really excited that I might just be able to slide under the car and find the answer before disassembly. Is that the consensus?

tom1394racing · 01-24-2009, 07:56 AM

If you've got a 2.7 you are correct.

If you've got an SC or a 3.2, you can count the fins.

lucittm · lucittm's Garage

Could we get the same primer on cylinders for the turbo cars? To include the 930, 965, 996TT, and the 997. The level of knowledge on this forum is simply awesome!

Mark

Henry Schmidt · Henry Schmidt's Garage

All turbo cylinders are Nikasil.
The earliest 930 were full finned 95 mm. 3.0.
The next generation was partial finned 97 mm 3.3 .
The 965 had a 97 mm full finned cylinder. Also a 3.3
Next we get the 3.6, 100 mm cylinder. Most were cast but the factory made some billet versions. They look very much like Nickies.
At this stage, I'm out of personal information.