What temperature does aluminum head warp? Ceramic coating/ 500° baking temp

[DeadlyAKrunna47]

Ok so my head is being disassembled to have ceramic coating done. But its now come to mind that the head is going to be baked at 500°f for a couple of hours. What temp does the aluminum start to warp? I cant find anything on the internet. We can assume since egt go from 700° to a high of 1600° so 500 cant hurt right? I just dont want to ruin my gorgeous curt brown ported head.

 

[bastarddsm]

500* for an extended period will take whatever heat treat is left in the head out. It will overage it. It probably won't warp it, but it will make it soft and difficult to keep head gaskets in.

 

[97gsxIA]

My first question would be why ceramic coat a cylinder head? It needs to dissipate heat not hold it in. And for our motors the head is where a lot (if not most) of the heat dissipates from.

 

[DeadlyAKrunna47]

Coating just the combustion chamber, and exhaust, and intake ports. Its just a thin heat barrier. It helps cooling system because the heat isn't transferred to head, it goes right out the exhaust. Its a little known secret that yeilds lots of power.

 

[bastarddsm]

Don't be so sure about that.^ On turbo stuff it's just an insulator that keeps heat in and causes detonation.

There's plenty of testing out there. From the research I've done it appears that the powergains are less than the measurement error in a dyno.

 

[DeadlyAKrunna47]

Ya i have done research, and heard reviews first hand. Its only positive.

A small explaination; usually right when the cold air hits in intake port its heat up from the head being 220 or w/e. But The coating isolates the air temp. so its like running a small hit of methanol.

 

[OGDSM1989]

Keep us posted on what you experience .... I tend to agree with that fact it may cause pre-detonation at the least higher head / cooling temps, but I have seen this done on some 2jz turbo motors and a stroked RB30 motor where they add this ceramic coating to these areas and the turbo hotside but not sure if makes any real gains as those motors are know for 1500hp either way you build them..... cant wait to see some numbers and first hand experience

 

[DeadlyAKrunna47]

I asked Curt Brown about it, he supports it! but like bastarddsm said its a hard thing to measure. You get a lot colder air in the combustion chamber so it helps with tuning. kinda like running higher octane. You hear about people coating pistons all the time. coating the head is a lot more tedious, but $/hp ratio its unbeatable if you can find the service.

 

[DeadlyAKrunna47]

Any other inputs?

 

[donniekak]

Most of these type of treatments are only beneficial for a short time (if they are at all), until carbon begins to deposit on the surface.

 

[DeadlyAKrunna47]

Stay on subject. ^ the tittle

Not looking for any opinions!

 

[ThunderChild]

Stay on subject. ^ the tittle

Not looking for any opinions!

Um...

Any other inputs?

If u don't want opinions, don't ask for them?

Donniekak hit this on the head. If this is for any kind of street driven vehicle it's money wasted, and possibly a way to take your nice head and junk it. Not worth the effort or cost IMHO. A fine polish on the chambers could effectively do the same thing for a similar amount of time, and the use of water/meth could combat carbon deposits.

 

[91stocker]

Scroll all the way to the bottom:
http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA2017T4

 

[ThunderChild]

That answers questions I had about my evo 8 exh manifold spacer, nice 91stocker

 

[bastarddsm]

That's the wrong material. A head would be A356 T6 It ages in the 400* range. So exposing it to temps greater than that will over age it, and it will get soft. That's not opinion, that's fact. The deck will flex more and you will have a harder time keeping a headgasket in it.

As for the coatings effects,

The heat transfer from the ports to the incoming air is very small. Like an order of magnitude less than the the heat transfer during combustion. That heat transfer cools the end gasses, without that the end-gasses ignite and cause detonation.

Also like donnie said once it's been run a while and gets a nice layer of carbon, you have a nice glowplug without a heatsink to deposit it's heat into.... more detonation. However it does pay a slight dividend in thermal efficiency.

I wouldn't put to much into what you see on forums. I'd be spending my time in the SAE journals. The topic your looking at is "Low Heat Rejection Engines"

 

[pauleyman]

I wouldnt do it. The statements above suggest a change in material properties as you were concered about. Im also of the opinion that even if the ports were cooler what is the rate of heat transfer for a very very short delta T. If you havent already intercooled enough to get it as close to ambient as possible sounds like youre chasing nth degree gains. You might be better served by latent heat gains of evaporation from water injection. The potential risks do not seem to outweigh the cons. It isnt just about heat. Its about rate of transfer and delta t. Same reason you can pass your hand through a blowtorch very quickly and not get bur ed. Very small delta t.

 

[screamineagle]

http://www.cerakotehightemp.com/finishes/C-186Q/piston-coat/

Use this cerakote product. Avoids your heat treating problem.

 

[Airsign89]

A while back I saw this article on different coatings, and it's worth a read.
http://www.hotrod.com/how-to/engine/hrdp-0612-engine-coatings/

 

[bastarddsm]

That was an article I thought of but couldn't remember where it was. Thanks.

 

[screamineagle]

I just completed an LS head for a customer last night using cerakote and have done my own 4g63 head with it as well. I have done TONs of pistons. Not so many heads because of all the work involved.

Saying that the ceramic coat doesn't work once there is carbon over it is essentially saying insulation in the wall of your house stop working when you cover them in drywall! Same concept.

 

[DeadlyAKrunna47]

I called the coaters, the actually just told me they bake heads at 240°f. The 500°f is for exhaust parts only. I asked them how long does the coating last and they told me they have seen coating from 20 years ago, and they still looked new. I asked about water/meth injection, they said it can preserve the coating because it cools, and cleans. but hey, who knows because they are the ones trying to sell it!?

I will post pictures in a week or so!

 

[bastarddsm]

Saying that the ceramic coat doesn't work once there is carbon over it is essentially saying insulation in the wall of your house stop working when you cover them in drywall! Same concept.

No that's not true at all. I don't think anyone said it doesn't work. Just that it's effectiveness is altered when carbon covers it.

 

[bastarddsm]

With out having a laboratory grade instrumented dyno, it will be next to impossible to really tell what effects it had. You need to watch cylinder pressure, flame propagation, heat rejection to the cooling system and exhaust, exhaust gas compostion, ect.

Cycle to cycle variablilty can change a pulls power as much as seen in the hotrod article. I'm not saying there are not any gains to be had, but it is not a given, and you are not sure what results may follow.

That hotrod example was far away from the detonation limit, so an increase in propensity to detonate might not show up.

 

[bastarddsm]

I called the coaters, the actually just told me they bake heads at 240°f. The 500°f is for exhaust parts only.

that's much better.

 

[screamineagle]

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Here is my head completed in piston coat.

There is no doubt this is playing with 0.5%-1% gains. I tell everyone thye will never be able to tell the effects of ceramic coating alone. It just one piece of the puzzle to building a a stronger, race ready motor.