airkooledchris wrote: ↑Mon Jun 10, 2019 10:53 am
high head temps from the special coating Hoffman heads?
does that make them less susceptible to damage when they got hot,
or is it supposed to make them run cooler?
High head temps normally occur from bad architecture, timing, mixture, or cooling system problems.
My architecture is fine, deck height, compression ratio, valve seating/shrouding, etc. If you read the ad copy below, you will see them talk about cooler running but hotter combustion. Yikes or bs.
I believe Len told me that the AMC heads have less cooling air flow-through (thicker fins) which had me concerned that the combustion heat was just not escaping fast enough out on the highway. So I made wilder and wilder adjustments to try to suss out my adjustment effects upon the heat. Really, if I can make it run hotter, then I have some agency over it and should be able to make it cooler by reversing my adjustment plus additional, right? I was just chicken to take my adjustments to the next level. Stupid engine was beginning to worry me when I had the wiper almost falling off the rich side of the track, the spring just stupid loose (rich), the mixture screw almost all the way down (rich), and a chokingly rich mixture, but head temps would invariably climb up to 430* on the hills. What? What?
Well hell's bells, let's get pissed and knock that damn wiper back lean a full friggen tooth, something I have never done, and then relax the spring so it will get the mixture richer right off idle.
Holy cats. 400* CHT at 65-70, 17 mpg, good steady idle, smooth pick up, wtf, wiper is lean!
So the coating alleges to protect the aluminum from rapid huge infusions of heat in transient conditions, but you know it is not any sort of "insulation" or we would be painting buildings with the stuff. It is just a infrared mirror coating. What happens when it is subsequently coated in carbon?
Here's some usual ad copy horsesh*t that actually folds back unto itself to help make no sense at all:
Setting up a thermal barrier in the combustion chamber also helps the chamber retain heat for more power potential. Again, assuming detonation does not become a problem, (WTF?- ed) this can increase combustion efficiency while lowering engine-coolant temperatures (seriously?). Aluminum heads, which are said to reject heat quicker than traditional cast iron, may see particular benefits from TBCs. (so if we are putting a heat barrier to hold heat, how does the aluminum "reject" that heat?? -ed) Barriers can also be applied to valve heads to keep them cooler.
Coating the inside and outside surfaces of exhaust parts with TBCs is said to increase exhaust-gas velocity, reducing backpressure (really?? -ed) and reversion.
Phooey on all the bullsh*t for our lawnmower engines that barely put out 17 hp per cylinder. This is just like "anti-bacterial" soap that does not clean your hands so much as strip them of their natural flora thus making you
more susceptible to infection.
Here is a Joe Blow poorly-spelled-but-thoroughly-corrected response in a Chevy forum:
One must also be careful in what particular coating is used where and when as sometimes depending on the cylinder head material (aluminum versus iron), piston shape, ring type , fuel used, and compression, the coating of all combustion surfaces can retain too much heat of combustion in the chamber and lead to other potential detonation, heat transfer issues and exhaust gas temperatures that are too high.
So, I have coatings, and I will measure exhaust temps in Death Valley and manifolds and fan housing as usual and we will see what happens.
airkooledchris wrote: ↑Mon Jun 10, 2019 10:53 am
im trying to focus on the work your doing and not the weight that you must feel upon your soul at this time. I hope for the best possible outcome in all that your working with currently.
Chris, I am anxiously waiting for my mother to get free of her prison. The Alzheimers gave me time to relinquish our relationship to the past (I only get to interact with her in full command of her faculties in my dreams). But there are also others I love who are skating close to the exit and they are still as sharp and beautiful and ornery as I have ever known, so they shock me with the finality of physical collapse while their hearts and minds struggle against the indignities like a wolf helplessly jerking against the steel trap. I shall miss them excruciatingly. I can't easily talk about my mother closing in on her departure, without the energy getting sticky with unspoken realizations. I just hate this. I'll get through it. You all shall be subject to their spirits that flow through me yet.
Good luck with the coming blast of relentless spirit and demand.
Colin