Ive got nikies! but also a possible problem...
 

Well i started to get ready to tear the top end off the engine to get ready for the head stud replacement, and found i have nikasil cylinders, Yay! They have 11 fins and say Mahle on the side, But with closer inspection i found cylinders 2 & 3 have different numbers than the other four which have matching numbers. Is this bad? Or is this okay as long as the height group number is the same. Heres the pics...

This is one of four cylinders that match

http://www.azporsche911.com/images/1.jpg

Here are the two that do not match

http://www.azporsche911.com/images/2.jpg
http://www.azporsche911.com/images/3.jpg

Check them with a magnet to be sure, I have seen both with 11 fins but usually nikasil don't have that center web between the fins

IIRC, the number in the triangle is the height group (5), so all of those seem to match. I don't know what the other numbers mean though; perhaps someone else can clue us in,

ianc

can you really only tell if you have nickies or not when the engine is pulled?

Todd

Someone posted a tip that you could pull one sparkplug and use a magnet on a stick to "feel" the cylinder wall with the piston at BDC.

I tried it, but couldn't feel anything, either it didn't work or I have alusils...

I know Mahle did make alusil but are rare. but from previous post i have read, Wayne has said if you have Mahle cylinders more than likely they are Nikasil. I will do the magnet test when the heads are off and look for the grayish milky coating known for alusil.

-Jeff

Any cylinder experts out there...

OK, not to hijack this but I have a question. I just did the magnetic test on my cylinders and they are VERY slightly magnetic, have Mahle on the side (of the one I partially removed) but they have the ridge and Craig seems to think that may indicate non nikasil...
Also, mine look somewhat gray inside but the light is not real good and they have not been cleaned too thoroughly. If it's slightly magnetic is that a sure fire sign?
TIA

Now these are clearly Nikasil, and have the "ridge" or "center web". I sure hope i dont have the rare mahle alusil though.

http://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/385010-fs-3-0sc-p-c.html?highlight=Nikasil

Anyways, can anyone answer my question about the 2 cylinders numbers not matching?

It might help if you could say which numbers specifically you're interested in. The 5's seem to match across all of them. The small indentations put there with a punch were probably made by someone who had the engine apart before and put them there for cylinder number identification. That leaves a larger number and a smaller stamping. Could one of them be the manufacture date?

ianc

What is the best way to mark cylinders and/or pistons permanently without possible damage? If they get sent off would the cleaning process take off any marks made to id them when being sent off to a machinist? I have VERY lightly etched a # in each cylinder head but was worried about doing some sort of microscopic damage. I can't see being able to use a punch like in the above pics without some serious impact and possible distortion. I've used metal punches before to indent ID #s but it was a major impact.

Buck, my cylinders were hit with an electric engraving pen on the skirt that slides into the spigot.

I guess then that a dremel type tool with an abrasive tip would work just fine...correct? Where is the best place to mark the piston...at the bottom on the part that does not touch the inside of the cylinder?

Well, the numbers that are bothering me are the large numbers to the right like the number 3, 1 and 0 and the small group of three. What do they mean? Four of my cylinders have matching numbers like the number 3, the height group #5, and whatever the the 706/023 means.

Yes the motor must have been pulled apart at one point, the punch marks are a give away that were put there by a mechanic. I just wanna know if all is needed to match is the height group number, if thats the case then i have nothing to worry about right. The car ran great and did not smoke.

Buck, Im sure the small punch marks will not and did not damage or distort the cylinders, obviously the numbers were put there by a stamp.

-Jeff

Cylinders
 

Guys,

Just checked my 87 spac book which says, page 47, Nikasil is " coated aluminum cylinders, yellowish" while Alusil is "uncoated aluminum cylinders, light grey"

The left mark on the cylinder is the manufactures id, the mid position mark is "the tolerance group for cylinder diameter" and the right side, the triangle with the number is the "tolerance group for cylinder height"

Ned

Thank you Ned!