Polishing the inlet internal but painting the outer?

Hi this weekend the inlet is coming off my 197 to be flowed and polished internally,once it's done I'd really like it painted ideally Matt black to hide the rough sandblast finish.

However I am guessing Renault decided to sandblast it for cooling purposes,by painting it Matt black do you think it will cause a noticeable issue either with inlet temps or performance...?

Id sacrifice 1 bhp for a nicer looking inlet but no more lol
 

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The finish on the inlet is a product of the manufacturing process (either sand casting or investment casting) which, as you've pointed out has a rough surface finish making a larger surface area for heat transfer to occur. Painting it black will change the emmisivity of the object and therefore increase the radiation heat transfer. The affect is probably negligible though.
 
I'm not an expert on metal casting and surface finishing, but it has a finish no better than it needs to be due entirely due to costs, it won't be due to cooling (assume you are thinking surface area related). Textured/crackle finishes look better anyway once painted. I'd go satin or matte black, or Honda Red :smile:
 
Thanks guys much appreciated! I like the Honda red ..that's a good call.I've gone down the yellow route with the rocker cover and calipers,I will get a project thread going at some point :tongueout:anic: