Cerakote and octane rating

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mgoblue9798

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Anyone use cerakote on pistons tops and head chambers?

Did you do the coating yourself or send it out?

Any testing done to see if lower octance would be tolerated after coating?

Any stories good or bad about using this stuff?
 
Very interested . I think RAMM was going to give it a try a while back but i never heard any updates .
 
mgoblue9798 said:
Anyone use cerakote on pistons tops and head chambers?

Did you do the coating yourself or send it out?

Any testing done to see if lower octance would be tolerated after coating?

Any stories good or bad about using this stuff?
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I *THINK* (going off my memory while watching Sick Week) that the Line2Line home page has some technical information about coating the tops of pistons.

Actually that site has all kinds of technical stuff on all kinds of their coating.

May be worth having a look there.
 
I remember when I first got into the hobby about 15 years ago, thermal barrier coatings were very popular. They've fallen out of popularity at this point for performance automotive gas engines as the gains are very small. Above about 2500 RPM the cycles happen so quickly there simply isn't enough time for very much heat transfer to take place through the head of the piston and combustion chamber surface.

Steve Brule noted on an episode of Engine Masters testing the effect of coolant temps on power, over his years of testing high-end race engines the reduction in power from higher coolant temps was due to its effect on limiting intake flow into the cylinders during intake stroke and exhaust/intake overlap. It wasn't due to heat transfer during compression and power strokes.

On that note when they tested iron vs. aluminum heads, the consensus was it wasn't due to differences in heat transfer in the different materials but due to hot spots in iron heads causing preignition. Smoothing and rounding off any and all sharp edges and unmachined cast surfaces in combustion chambers of iron heads is very important to help prevent that.
 
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MopaR&D said:
I remember when I first got into the hobby about 15 years ago, thermal barrier coatings were very popular. They've fallen out of popularity at this point for performance automotive gas engines as the gains are very small. Above about 2500 RPM the cycles happen so quickly there simply isn't enough time for very much heat transfer to take place through the head of the piston and combustion chamber surface.

Steve Brule noted on an episode of Engine Masters testing the effect of coolant temps on power, over his years of testing high-end race engines the reduction in power from higher coolant temps was due to its effect on limiting intake flow into the cylinders during intake stroke and exhaust/intake overlap. It wasn't due to heat transfer during compression and power strokes.

On that note when they tested iron vs. aluminum heads, the consensus was it wasn't due to differences in heat transfer in the different materials but due to hot spots in iron heads causing preignition. Smoothing and rounding off any and all sharp edges and unmachined cast surfaces in combustion chambers of iron heads is very important to help prevent that.
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Yeah, I‘m not sure I agree with some of that.

A reduction in coolant temp also reduces intake charge temperature, which increases detonation resistance.

And the test where they loaded the engines to test detonation sensitivity was at best questionable.

To replicate that test in real life you’d have to be pulling a serious grade, for a long pull and never downshift.

No one in their right mind does that. So that test is questionable in that it doesnt really prove that aluminum heads are more detonation sensitive that cast iron heads. It just proves that cast iron can’t be as abused as aluminum can be.


Abuse is unacceptable.
 
Coating the piston or chamber has nothing to do with the octane rating of the fuel. Detonation and pre ignition are two entirely different animals. Pre ignition could be changed by coatings but octane and detonation tolerance will not.
 
Rat Bastid said:
Yeah, I‘m not sure I agree with some of that.

A reduction in coolant temp also reduces intake charge temperature, which increases detonation resistance.

And the test where they loaded the engines to test detonation sensitivity was at best questionable.

To replicate that test in real life you’d have to be pulling a serious grade, for a long pull and never downshift.

No one in their right mind does that. So that test is questionable in that it doesnt really prove that aluminum heads are more detonation sensitive that cast iron heads. It just proves that cast iron can’t be as abused as aluminum can be.


Abuse is unacceptable.
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Oh the coolant temp definitely affects detonation resistance. I was specifically referring more to the old myth that aluminum heads themselves resist knock because it pulls more heat from the chamber and you 'need to have more compression to make up the difference'. Only looking at it within the cylinder; when you take the intake temps and heating up of the exhaust port under load into consideration it's a whole different deal.

I agree their knock test didn't really show anything conclusive. They didn't even really test for knock I assume since they weren't willing to risk damaging the engine and they didn't have any knock sensors with automatic timing retard hooked up to catch it before it caused damage.

To do it "right" they should have put in knock sensors and thermocouples in the intake manifold, head intake port and exhaust port. When I worked in the Engines Lab at CSU the test engines would be covered in a mass of thermocouple and sensor wires because they monitored EVERYthing. Those were all larger industrial/commercial/agricultural lower-speed diesel and natural gas engines though, no fun performance stuff unfortunately for me lol. But still super interesting.
 
TT5.9mag said:
Coating the piston or chamber has nothing to do with the octane rating of the fuel. Detonation and pre ignition are two entirely different animals. Pre ignition could be changed by coatings but octane and detonation tolerance will not.
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Swain claims otherwise. Thats why I was asking about any real world experience or testing that anyone knows of.

"The ceramic also spreads the heat evenly over the entire coated surface reducing detonation, pre-ignition and allowing the use of lower octane fuel."

 
Well they are the ones selling the product so they're going to claim whatever they can to make people want to buy them, happens all the time...
 
MopaR&D said:
Well they are the ones selling the product so they're going to claim whatever they can to make people want to buy them, happens all the time...
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No doubt, thats why I am asking around. Appreciate the input sir.
 
mgoblue9798 said:
Swain claims otherwise. Thats why I was asking about any real world experience or testing that anyone knows of.

"The ceramic also spreads the heat evenly over the entire coated surface reducing detonation, pre-ignition and allowing the use of lower octane fuel."

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Yea they do “claim” that but a lot of people misuse the terms interchangeably and they shouldn’t.
 
It's a proven fact that with good coatings and aluminum heads, you can get away with 14:1 compression on pump gas. The coatings are the key. If you really want max performance you also need to run longer rods and really short strokes and big bores. That way it also revs really good.
 
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