The $ vs the benefit... Coating the exhaust ports means that you would have less heat in the head going down through the header and away of the engine...

That is the reason you should coat the exhaust port...

I'll see what happens...

 

Keep in mind that when it comes to gas flow, HEAT = VELOCITY. Preventing exhaust gas heat from being transferred to the exhaust runners will improve the velocity of the exiting gases. This not only helps evacuate the combustion area, it also decreases backpressure as the exhaust gases lose heat and velocity and an increase in the velocity at which the exhaust gas plug enters the collector will increase the strength of the scavenging pulse. As is the case with most thing related to an IC engine, one small change can have a multitude of side-effects.

That said(whew), I believe you should coat the headers first, for all of the above reasons plus one other. Thin wall headers are notorious for transferring heat into the engine compartment. This can decrease power and reliability. Additionally, I've seen actual tests where properly coated headers (thermal barrier on the inside of the pipe, not a cosmetic coating on the outside) actually improved cooling system efficency. Never a bad thing.

Your second comment, regarding retaining heat in the combustion area, is essentially true. Keep in mind though, that like most good things, there are limits (this, of course, would not apply to any internet-video sequel/series Paris Hilton may be planning to release). Too much heat in the combustion area will lead to pre-ignition and possible detonation. The easiest cure for this is to reduce ignition timing to reduce combustion efficiency. So there's a trade-off to thermal barrier treatments. The extra retained heat will exert more force on the piston, but to limit the heat there needs to be a reduction in the amount of available energy that is released.

 

It will make more power with less timing then...

I dont know if mine is for cosmetic reasons, but I do know that they are porous and not smooth and white on the inside...

Anyways... I want to know if there is any REAL TEMP difference to go with the coating on the heads.

 

Well,... yes and no. Because less heat is transferred more force is exerted on the piston. But to limit heat build-up, less of the available fuel is combusted and therefore less energy is released.

As for your question: I don't yet have any experience with internal engine coatings, but it makes sense that any heat not transferred into the cylinder head or block, is heat that the cooling system does not need to remove and transfer into the radiator.

I have though, done the coatings on my SLP headers. Two coats of Cermet on the inside, one on the outside and a coat of CermaKrome on the outside (overkill to be sure, but it's cheap like borscht when you do it yourself). Last summer, while stuck in stop-and-go traffic on Columbia Street in Kamloops(about a 6% grade) on a 43° C afternoon, my temp guage was barely past 200° F (it's an ex-American IROC). I think the header coatings had a small effect, but the cooling system mods were largely responsible.

 

I would think that since without coating I would imagine not all of the air/fuel mix is combusted so you are missing out on that little bit of power and gas mileage, but with coatings keeping heat in there it would combust most of the mixture thus better gas mileage and more power, but I wouldnt think you would have to remove much timing, like the guy above said he runs what, 32* advanced on a GN and way more boost than without, sounds to me like it is supposed to reduce detonation????

 

Without coatings at all

I ran 5 psi boost 383 9:1 AFR 93 shell gas and I ran 36º total advance with 220 IATs!!!!!!!!

 

and with coatings you could have ran less total advance, and as a result gained hp.

Any timing before TDC is merely a consequence that a spark-ignition system can NOT ignite all the charge at once. If it could, we'd be running 0* total advance, and elliminating the "negative work" part of the ignition cycle from engines.

Coatings help isolate the heat in the combustion chamber and should result in decreased timing to get peak hp. The hp peak reached should also be a bit higher as a result. HP gains from ceramic coatings are not related to friction (different type of coating is used for piston skirts and valve springs) but instead the focus on speeding the flame front/ignition.

Just what I've read though...

 

As regards ceramics for friction-reduction: there are various ceramic coatings that do just that. At the extreme end of the scale, Orbital Engines of Australia built a low-friction engine several years ago that developed nearly 200 hp/ liter (take that Honda). The block was entirely ceramic. I've also heard talk of ringless ceramic pistons, but have trouble seeing how that could be practical. Using ceramics to retain heat or reduce friction won't make hp, but it will decrease the amount of energy lost to friction and thermal transfer. That's important because in the typical IC engine, only about 30% of the energy released by combustion is translated into crankshaft motion. Put into overly-simplistic terms, to see 300 hp at the flywheel, you need to burn 1000 hp worth of fuel. Of the 700 'lost' hp, 50% is frictional losses, 30% is thermal transfer, and 20% is pumping losses and other causes (someone correct me if my numbers are off). So in a sense, friction-reduction should take priority over heat-retention, but it is easier to recover losses from thermal-transfer than from friction. The pistons rings are the worst offenders to frictional losses, but they're kind of necessary

 

those numbers sound about right. The one that stands out in my head seems to go like this:

1/3 of the chemical energy turns into kenetic motion at the crank.
1/3 of the chemical energy turns into heat in the exhaust.
1/3 of the chemical energy turns into heat in the coolant (this includes internal friction losses)

10% to 20% of the kinetic energy in the crank turns to heat in the oil (via friction again) when it reaches the wheels. So total energy to the wheels is ~30% of the fuel's BTU's.


I'm sure this is off by a fair bit depending on engine design... but the obvious target here are those 2/3's energy that just becomes heat (which we currently "waste" by bleeding it off to the surroundings via radiators ).

The other stat that comes to mind is that GM engines built in the 1930's were 90% more efficient than those built in 1900's. Since the 1930's, our engines are now 9 TIMES as efficient (900% more). Obviously that's the "point" of progress... but it still boggles the mind. I belive that applies to 1990's technology though, so the next C6 or caddy engine will probably push that stat even higher.

 

yeah, porsche has some engines with ball bearing main bearings, i wonder how much power they get off of that. i have heard that the military did some testing on all ceramic engines with no cooling systems for reliability. however, the engines got SO hot that it killed the power. mabey somebody knows more on this and can chime in.