Gorilla snot? Again news to me!

 

I can make a video if you all want haha. Kidding aside, The plating of the alum pistons is stated in that paper also. The piston is hyper-eutectic Al-Si but only the skirts are iron plated, as the magnet won't stick anywhere else except there.

 

That crossed my mind, interesting.

 

Yes, the thrust surfaces of the piston is the only thing that needs it. In theory, I could grab any off-the-shelf 2618 or 4032 piston and have it iron plated to make it FRM friendly as long as the proper P/W clearance is maintained.

 

OK, I was wrong. TIL

 

Expansion rate and clearances is still a key element though between the various combinations ie forged aluminum pistons, FRM, iron bores etc.

 

Also was told coating the bore is an option <if over+.25 max o/s piston needed>& if using a non oem piston 2618 & 4032,but piston slap from cold & expansion reduces longevity 20k +/-iirc & even using the .25 os oem could work,but again longevity may not be cost effective.
Wet/dry liner inserts will have the above longevity issue also, piston 2618/4032 only options.
I bought another engine
Another use for my old pistons though as a post it for notes using a magnet

 

Yep, why i stay away from "built" engines for this car. Typical iron sleeve/forged piston to wall clearances have to be larger then oem and that means piston slap and less longevity.

 

Mahle has the 4032 piston with the correct coating... either iron-phosphate or something along the lines of Ni-P-BN. I agree that larger P/W clearances do not lend themselves well to longevity. Then again, who else makes a 4032 s2000 piston for iron sleeves? that's the issue.