Intake Refinishing Alternative to Powdercoat
This is the process I used for refinishing my intake and cam covers. I researched the best process to refinish the aluminum/magnesium (Al/Mg) alloy and came up with this process. I wanted to have more of a variety to color schemes then offered through most powdercoaters. When inquiring around to all the local paint shops and metal finishing companies, no one was willing to touch magnesium to refinish with any type of guarantee it would work. The problem seemed to be that there was no good way to etch the Mg alloy so that you could get a good base for the primer to stick. Even the factory process could be improved upon as we see our current intakes paint peeling off. My searching lead me to a chemical company out of Chicago (Sanchem) that offers a converter for magnesium alloys. The conversion coating I used is the SafeGard CC-3400 RTU (Ready To Use) that runs $40 for a gal. I used about 12oz for the entire process. http://www.sanchem.com/safegard_cc.html . This converter essentially etches the metal alloy and allows for a primer to be applied that will result in excellent adhesion to the metal. I spoke with the lead chemist and he seemed to be familiar with the type of Al/Mg alloy that was used in the production of the intakes and cam covers. He then lined out the process I needed to follow for best results as the converter is time dependant.
First obvious step is to have the parts stripped. Chemical stripping is too harsh and sanding is too time consuming so I decided to have the parts blasted. I chose to go with aluminum oxide blasting. Aluminum oxide isnít too aggressive and I didnít need to worry about beads being left behind. Here are the parts after the blasting process. They come out a bit rough to the touch.
When I got these parts back I blew them clean with compressed air. Once I had that done I completely washed/immersed the parts in white vinegar. The parts will fizz and get real warm as the acid reacts with the Al/Mg. Continue to soak them for a few minutes and then wash them clean with distilled water and let dry. Here are some additional photos after that process. The vinegar acid bath seemed to smooth out the roughness from blasting and take care of any of the aluminum oxide blast media left behind.
Once that had dried completely I spray/coated the parts with the converter, let it soak for a few minutes and then wipe/air dry.
Once the part is dry you have a 2 hour window to apply primer. If you donít get it sprayed in that time frame the primer will not make a good bond. You will have to go back to the vinegar step and start over. I chose to use Dupontís ChromaSeal urethane sealer. Since the converter acts the same as an etching primer, I went straight to the sealer. The sealer gives a nice level smooth surface that you can paint over with no sanding. Here again it is time dependent. Follow the manufacturerís recommendations but you can topcoat after about 1 hour and up to 16 hours. After that you will need to sand the primer to promote adhesion. This product has excellent leveling for the topcoat and EXCELLENT adhesion with the converter. If you would ever want to repaint it down the road you would just have to scuff sand it and repaint. It would not need to be striped again due to having the good base sealer in place.
I sprayed a factory Porsche color with Dupontís ChromaBase paint and a high temp engine clear over that. In hindsight I wish I would have used the ChromaBase high performance clear as the high temp clear has yellowed a bit but not too bad. The color has a pearl essence in it so it changes color a bit depending on the light. If you would prefer to skip the clear coat, you could just go with a single stage paint that would need nothing else once sprayed. Itís all personal preference. I did this approximately a year ago and have had no issues. When reassembling the intake I wanted to level off the surface area of the intake where the intake gasket goes for mounting to the engine. I had to aggressively sand it down to get it off. Even then the primer didn't want to come off easily. Its adhesion is excellent and you can see from the pic where I worked to get it off.
Here is the final product. I hope that this helps others who would like an alternative to powder coating. Thanks