Just bought a set of challenge cats for my 360 spider and wanted to ceramic coating them. Some folks told me NO - so that the cats can release the heat. Some folks told me YES - to reduce eng. comp heat. I am confuse on which is the right answer. I see a lot of aftermarket cats being coated so must be ok? Would someone please give a scientific advise on this? Greatly appreciated in advance.
Don't do it. I don't know what kind of scientific measure you're looking for, but the reasons not to are that (1) if you overtemp a cat, it will melt and become ineffective, possibly a gross exhaust restriction and (2) the matrix (the grid inside of the cat that holds the precious metals) is held in place in the can by a wrap that's generally also got a finite temp limit and can fail and leave you with a rattling cat. Ask Judge4re if you get confused.
Those guys are <math/science>idiots. They think that the painted header at 527dF and the ceramic header at 205dF means that the temperature was reduced 50%. I just wonder what they would think if one header were 10dF and the other at -10dF would they propose that the coated header was minus 100% of the non-coated headers? No, they simply do not understand that temperature comparisons HAVE to be made relative to absolute zero to have ANY relative MEANING. For the given example: 527dF = 986dR and 205dF = 664dR then 664/986 = 67% or a savnigs of 33%.
Be that as it may Ceramic Coating does lower under hood temps and that's a good thing. Coatings also protect CF and enable exhaust to come through CF cleanly as in F1 cars.
As Alex Trebec would say... "Sorry Mitch, that's a wrong answer"... What's important to heat transfer is the DIFFERENCE in temperature between the heat source and the heat sink, the respective temperature difference available to transfer the heat being the driving term. More simply put, the important thing is how many BTU's are transferred out of the exhaust plumbing and into the engine compartment. Assuming the same conductive coefficents (same airflow over the headers or exhaust and same air inlet temperature) then dropping the temperature difference by half will drop the amount of heat transferred into the compartment by about half since the air around the system (the heat sink) doesn't change in temperature.
Here's a related question. What about the differences between typical aftermarket headers that are simply bare tubes vs. OEM style headers that are wrapped in an insulation? If both flowed the same, which would be "better" and why? The bare tubes or the wrapped ones?
What exactly do you mean by "better"? If you're wondering about performance then you don't lose performance by wrapping your headers, instead you merely reduce engine bay temperature. The total heat transfer from the exhaust pipe is the same regardless whether there is insulation,... the difference is where it goes. With an un-insulated tube the heat transfers to the surrounding air where as with an insulated tube, the heat transfers to the insulation (where some of it is absorbed) and then at a reduced amount, to the surrounding air. Race cars typically don't need to wrap their headers because they are exposed (or air is channeled directly to them) which greatly reduces temperature.
Note: I was NOT complaining abut the efficacy of ceramic coatings--at all--they work. And if you look closely, you will not see any mention of ceramics, just of the ratio of temperatures. Unfortunately the writer of the article never passed a jr. high physics or chemistry class.
Wrapped headers die an early death. Headers coated only on the outside die an early death. In both cases, the death is cause by the heat getting into the steel, but then having no way out. The header heat shield in the OEM headers contributes to header death and contributes to dinoplex life. Ceramic coating on the INSIDE adds life to the header and life to the parts in the engine bay. Ceramic coating on both inside and outside is more of a mixed blessing with life increases for parts in the engine bay (cooler), and a minor life decrease for the headers themselves (steel runs hotter). inconel without ceramic coating is just about as good as 303 stainless with coatings in terms of heat transfer into engine bay. 321 stainless transfers less heat, and survives more heat than 303 (or 304).
Thanks for the explanation. What is "dinoplex" life? Referring to fluids, rubber parts in the engine compartment that would be subject to more heat from unwrapped headers?
I guess that Mitch refers to the life expectation of the the ignition system, i believe the 360 uses a Motronic with Bosch ignition modules. The last Ferrari using a Dinoplex ignition was the 512BBi. Best, Adrian
I'm not a fan of ceramic coatings, but remember, we don't design these things to last a lifetime, just what is mandated by law.
