Offshoreonly.com - Pistons and coatings

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I always thought coatings were only .001 - .002”!

Also that they were for friction reduction and or heat control.

Never realized people used it for clearance issues.

On ring packages….., another Engine Masters episode??

My theory is, the more the meat, the better the seal and I’ll give up some friction to get that and the better expected longevity.

Also prefer tighter end gaps and will file to fit.

I spend way more time in 2 stroke OBs where our options are scarce.

I do know that some of the Merc drag motors run a SINGLE skinny ass ring!

It’s funny that so much of this is “theory” and near impossible to prove.

You could write a book on the differing theories on break in procedures!
Also a huge fan of.

Quote:

Originally Posted by articfriends (Post 4886940)

I have a local guy doing coating now (component coatings) . I have had pistons coated to fix bore clearance issues BUT not on street or marine applications, typically drag race and mud boggers. I call those rebuilds "10 hour rebuilds", a hill billys going to go out , smoke a bunch of weed, get drunk AF then hold his "mudder" acrossed the pit at wot for 30 seconds 2 or 4 times then park it. When it gets wet he'll go ahead and hold it on rev limiter in anger trying to "clear it out". So heavy coating a 4.623 dia piston thats going back in a bore that measures 4.634/ 4.635 after cleanup honing will get these guys thru 10 more weekends of "bogging" vs a new block or custom pistons but NOT a good long term fix!

I used line 2 line coating to take up excessive clearance. My pistons were 007 to small. The coating filled in the gap in my "street" engine. 2200+ miles since done last year with no issues. Engine sees 7000rpm and seen over 30lbs of boost with a very short skirt piston that sticks out of the bore 1/4" or 3/8" (would have to check my build notes) Hopefully it keeps going for a longgggg time.

Is this the best way to go? Of course not.

If my memory is correct, line 2 line will do up to 015 thick coating There comes a time where the rings are sticking out in the line of fire/heat.

Quote:

Originally Posted by underpsi68 (Post 4886958)

Yep, Ive used line to line and component coatings for same thing, usually to save from buying a block where its at its limit or high dollar race pistons that are too loose