Ceramic coated pistons

[Dsl_Dog_Treat]

Ok I know this may be a longshot, but does anybody have coated pistons and have had them out since the coating and was anything noted about them?

Im trying to see if the ceramic is holding up to the heat and if so how do the undersides of the crowns look.

After tearing down the engine the rest of the way, all but 2 piston crowns were scorched. Some not as bad and not seeing a consistant pattern for the ones who's cooling jets were out of alignment.

I'm beginning to wonder if the coating is a sufficient thermal barrier on crowns that have been shaved.

 

[icanfixall]

Milling the pistons does have a minimum thickness. Or a max to be removed and still have a thick enough piston dome to disapate the heat. I personally would not mill more than 20 off the tops. Add a set of low comp pistons and the overall amount milled and machined into the low comp is going to equal 30 off the tops. Thats going to make the pistons 1 thousands above the cylinder is the worst factory spec. The factory calls for the pistons to raise up out of the cylinders a maximum of 31 thousands. The ceramic coating has a thickness but thats dependant of the person applying it.

 

[riotwarrior]

UM you should know by now...PICS PICS PICS....did I mention pics?

 

[Dsl_Dog_Treat]

Darrin is gonna post up a couple carnage pics for me.

Well I'm wondering how hot the flatlander engine really got. Further dissection shows the rod journals on the crankshaft got hot but bearings are fine.

Precup throats........ All 8 cracked!

Until the heads are pressure tested, I think I have a set of 6.9 studs.

How I discovered the precups crack was when I was cc'ing the heads this morning.
I did learn that the precups were 18cc's, intake valves 2.8cc's and exhaust valves were 2cc's.
So with that I can now crunch some numbers to see exactly where the compression ratio was on this build.

So project twin turbo build has officially returned to R&D.

But is not dead. I'm not giving up on a pair of twins for this platform.

 

[Darrin Tosh]

Pics as promised,

Crank Journal:

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Cracked Precup:

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Inside Precup:

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[Darrin Tosh]

Now that I posted them I had a chance to look at them,..HOLY CRAP! That thing must have gotten HOT! I cant believe the blue on the crankshaft!

 

[Dsl_Dog_Treat]

Thanks Darrin.

This animal got hot!
Hopefully the heads will pressure test good but am concerned with the amount of erosion on the head surface where the block water jackets meet.

 

[riotwarrior]

WOW....I mean ya...that got really fawkin hot fer sure! *** happened?

 

[The Warden]

I don't have anything to add, but want to thank you for asking this question. I'm very interested in the idea of ceramic coating (pistons, exhaust manifolds, turbo up-pipes, etc), but I've heard that there's a potential problem with the ceramic separating from the metal and causing serious problems...and I have yet to hear anyone report back after running ceramic-coasted anything long-term. I'm definitely watching this thread closely...thank you for starting this topic

And HOLY MARY that engine got hot...

 

[Black dawg]

how does a crank get blued and the bearing live through it??

Any other signs of oil starvation other than pistons and rod journals?

I have seen many cranks that looked like that, but the bearing was wasted and the rod was turned black.

 

[rjjp]

I did learn that the precups were 18cc's, intake valves 2.8cc's and exhaust valves were 2cc's.

You wouldn't have numbers for a stock engine, would you?

 

[Dsl_Dog_Treat]

You wouldn't have numbers for a stock engine, would you?

Richard, I've got a set of 7.3 heads that I can check for ya.


I havent a clue as to why the bearings are fine and I'm not sure of the history prior to it initially being assembled. It has me puzzled too.
Rod bearings are stock so the crank hasn't been turned down.
No other issues found.

 

[PwrSmoke]

Ron- That crankshaft hadn't been welded up and turned had it... or nitrided? THe journal looks fine but it's outside the journal that looks hot... as if it has been welded up.

 

[Dsl_Dog_Treat]

Ron- That crankshaft hadn't been welded up and turned had it... or nitrided? THe journal looks fine but it's outside the journal that looks hot... as if it has been welded up.

OOHHH!!! Good point!

Jim it doesn't appear to have been welded but since all 4 journal ends have equal excessive heat marks it may very well have been nitride treated. That may be a question for Ken since he did the build.

Depending on where I'm at with it by rally time, it may be coming along with the rest of the parts for show and tell.

 

[icanfixall]

Bingo.... That crank appears to have been welded up and ground back to standard. When we talked today Ron I should have caught that idea but seeing it here posted makes plenty of sence. A poorly ground crank can turn blue like this by pushing ******* the grinder. Also a reground crank needs to be acid tested to know the metal has not been burned when the grinding is done. The acid used is in my shop manuals that are loaned out but I think it was nitric acid.. I really don't recall so don't try to use it till I know for sure. Its a long process. You don't just pour it on and watch either... Maybe utube has a viedo..... Anyway, the bearings you say looked fine so the crank looks terrible... The tow items don't fit the message. I'm not going to say the crank is shot or its still ok. Only the acid test will tell you that. So lets not go off half cocked if you know what I mean. Continued R&R is what should be done first. Collect al the data and information but don't predicide whats wrong till all the facts are in...