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Besides an improved appearance, the ceramic coating only offers a minor tangible benefit from radiant heat transfer - but only if the correct color range is selected. I'm not aware of any studies done specific to engine compartments and the reduction in radiant heat, but there are numerous other published studies pertaining to radiant heat.
Painted coatings, as noted, begin to fail after a few years - and therefore do not offer the best long term solution.
I've used both ceramic coating and VHT header paint and found similar results to what both @WestInc and @wopfe have experienced.
I installed ceramic coated Bassani headers on my 1993 Ford Lighting shortly after I had purchased it new. The factory exhaust manifolds were tubular headers and not cast iron, so other than better flowing, the Bassani headers and the factory units were very similar in construction and I can say that there was a noticeable reduction in underhood radiant heat. The 928's engine compartment by comparison is vastly more compact so I'm not surprised that those who have had their manifolds coated are not noticing much of a difference.
My recommendation of using the VHT header paint was in response to @ClassicCarBuyerinquiry about coating his exhaust system to which I took to mean his tailpipes and mufflers. If he meant it to also include the pieces forward of that (the cat pipes and headers) then I would agree with WestInc in that it would not last very long in those areas and ceramic coating is better choice there.
FWIW, I painted my RMB with DupliColor Engine Enamel in the summer 2021 and it is holding up very well after 3 years. However that far end of the exhaust is not seeing that much heat in comparison. I only chose engine enamel over the header paint because I wanted a satin black finish on the RMB and VHT only offers flat black in that product.
I've used both ceramic coating and VHT header paint and found similar results to what both @WestInc and @wopfe have experienced.
I installed ceramic coated Bassani headers on my 1993 Ford Lighting shortly after I had purchased it new. The factory exhaust manifolds were tubular headers and not cast iron, so other than better flowing, the Bassani headers and the factory units were very similar in construction and I can say that there was a noticeable reduction in underhood radiant heat. The 928's engine compartment by comparison is vastly more compact so I'm not surprised that those who have had their manifolds coated are not noticing much of a difference.
My recommendation of using the VHT header paint was in response to @ClassicCarBuyerinquiry about coating his exhaust system to which I took to mean his tailpipes and mufflers. If he meant it to also include the pieces forward of that (the cat pipes and headers) then I would agree with WestInc in that it would not last very long in those areas and ceramic coating is better choice there.
FWIW, I painted my RMB with DupliColor Engine Enamel in the summer 2021 and it is holding up very well after 3 years. However that far end of the exhaust is not seeing that much heat in comparison. I only chose engine enamel over the header paint because I wanted a satin black finish on the RMB and VHT only offers flat black in that product.
I have the most experience with ceramic coating on exhaust manifolds and tuned pipes on 2-stroke engines. No cast iron ones, all waterformed and/or welded steel. When we're dyno-ing the systems and measuring exhaustgasses etc, it is very obvious that the ceramic coating helps to keep more heat in the pipe/system than it does without. Cannot argue with those measured figures. I can imagine that it doesn't do exactly similar figures on a cast manifold on a car engine. But on the newer 928 s4/GT/GTS thinner exhaust manifolds it should have some effect. But as Brent says, in the 928's small engine compartment there is no easy way to escape the heat...
12-28-2023, 12:16 PM
