Cerakote and octane rating

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.