recognizing alusil

[Rick!]

Call US Chrome or Millennium Technologies for help on using the right stones for honing Nikasil.
I worked at a gas powered fun factory for a while and Nikasil plated bores were honed to size daily.

[MotionMachine]

Alusil is not applied, the parent material is a high silicon content aluminum. It's a special process to hone them, I did a Youtube video showing how I do BMW V8's, using a profilometer to ensure that each step arrives at the right Ra value before moving on to the next step. I'll try to attach the video on this post, never done it on this laptop.
Oh, yeah, shortly into the video I say nikasil, but I meant to say alusil. Nikasil is a difffeent video.

Question about that BMW V8. Is it an open deck block? If it’s an open deck block, have you found a large benefit from the deck plate? When you torque the heads and the main girdle/caps, does the bore end up much more round if you processed it with the deck plate compared to without the deck plate?

I use a deck plate on everything aluminum. If I don't have one, I make one. The S62 BMW's distort about .0015" at the top of the bores. The last step in the process uses a silicon paste that etches away the aluminum surrounding the silicon in the parent material, producing a silicon surface for the piston/rings.

Regarding Nikasil, I have tested with a profilometer before and after results using the BR aluminum oxide flex hone on used cylinders that I had honed to size originally with diamonds on the SV10. The numbers improve after about a dozen strokes.

[ptuomov]

My question is does the deck plate result in a bore that is more round or less round when both the heads and mains have been torqued? Have you measured that? Using a deck plate is common sense to me, but every now and then I hear someone credible say that the German open deck aluminum block, head, and main girdle/cap castings are designed to be bored and honed without a deck plate. The view/theory being that the head and main studs/bolts being torqued to spec will together turn the bore more round of its bored without a deck plate than when it’s bored with a deck plate. I’d like to have data to prove that theory wrong, but I don’t. Do you?

[ptuomov]

Regarding Nikasil, I have tested with a profilometer before and after results using the BR aluminum oxide flex hone on used cylinders that I had honed to size originally with diamonds on the SV10. The numbers improve after about a dozen strokes.

What's your target in terms roughness average on profilometer for Nikasil/Nicom bores? Where do you typically start with used cylinders and where do you end up after the BR aluminum oxide flex hone?

[MotionMachine]

The nikasil sleeves that I hone to size (approx .004" stock removal) requires an Ra of no greater than .3um. These are Mahle specs. But I check all 7 parameters when I do them initially, Ra is just one. The Ra is about half that number after use, the flex hone increases both the valley and peak number back closer to the original specs.

[ptuomov]

I have a follow-up question. What does it mean for “rings to seat” on Nikasil bores? The piston ring is a precision machined piece. If the Nikasil bore “wears” down from RA of 3um to RA of say 2um over use, what does it mean for piston rings to seat to the bore? How much do any break in procedures, all the oil and holy water spent, really matter for a fresh Nikasil bore? It seems to me that it is either ready out of the box or will break in over a very long period that can’t be honestly described as any sort of break in period.

[ptuomov]

I found this document overall informative:

http://lnengineering.com/files/2019-LN- ... ystems.pdf