ring gap on ceramic coated pistons?
I'd say don't change the gap.... I don't see how coating either the skirts or crown would change how you'd want to gap the rings.. coating the skirts would reduce friction. Coating the top would help keep the piston a little cooler. Either way, I don't think I'd change the gap. I gapped my diamond rings at .016 top, .018 2nd.. I have a stock bore, lunati forged flat tops with moly coated skirts... Couldn't tell you how it runss though.. heads aren't on yet.
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I've wondered about this as well. My thoughts are that if the crown is running cooler less heat will travel down the lands and the top ring may also be cooler so you could tighten the gaps a little if using file fits. You could certainly aim for the tighter recommended tolerences and that should be safe. This is what I shall be doing. It may only effect the top ring. I'll look to sae recommendations and tighten the top ring gap by a few extra thou.
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Originally Posted by Mike at Boost Performance.co.uk
I've wondered about this as well. My thoughts are that if the crown is running cooler less heat will travel down the lands and the top ring may also be cooler so you could tighten the gaps a little if using file fits. You could certainly aim for the tighter recommended tolerences and that should be safe. This is what I shall be doing. It may only effect the top ring. I'll look to sae recommendations and tighten the top ring gap by a few extra thou.
see...this is what I was thinking...
that there will be less heat moving down the piston which would mean less heat in the rings and thus you could run closer ring gap.
I am having the tops ceramic coated and the sides coated with the teflon/moly coat
In the early 80's we were ceramic plasma coating both the piston tops and the combustion chambers and the rings were seeing much higher temps due to the ammount of heat being trapped in the chamber.Rings would lose there tension
and micro weld to the ring lands also the coatind we were useing was the same
thing the heat tiles for space craft were made of and the coating went on .013 thick.
Naked alumium in the combustion chamber is a big heat sink.What I am saying is you
may have to increase end gap and use a premium ring material.
and micro weld to the ring lands also the coatind we were useing was the same
thing the heat tiles for space craft were made of and the coating went on .013 thick.
Naked alumium in the combustion chamber is a big heat sink.What I am saying is you
may have to increase end gap and use a premium ring material.
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So you’re saying:
Because the aluminum heads and pistons can not dissipate as much heat (when coated) as they otherwise would, the rings will actually be subjected to more heat and thereby might be requiring more end gap to allow for more expansion?
The rings are the "standard" Diamond Pro-Select Piston Rings that everyone seems to be running (they are on Thunder Racings page). Any input on these?
Because the aluminum heads and pistons can not dissipate as much heat (when coated) as they otherwise would, the rings will actually be subjected to more heat and thereby might be requiring more end gap to allow for more expansion?
The rings are the "standard" Diamond Pro-Select Piston Rings that everyone seems to be running (they are on Thunder Racings page). Any input on these?
Well I could see that on an engine where both the combustion chamber and the piston top was coated, but that is not the case here. Just the piston is coated and the head is the heat sink, so I would think that the piston would stay cooler.
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I didn't write it (didn't think to mention it), but yes the heads will be coated. I am going to have the pistons coated and then have the chamber, valves, and exhaust ports coated (might do intake ports but I'm not sure yet).
