How-To Turbo Refinish with Powder Coating
(Words and Photos: By James R., Eastwood.com, March 2016)
Whether you're adding a turbo to your car or just refinishing the one you already have, the best option is powder coating. We have everything you need to completely restore your turbo in an extremely durable corrosion-free finish that other coatings simply can't match.
The turbine or exhaust side of a turbocharger can get very hot during operation; sometimes exceeding 400 deg F. Standard powders are usually only rated to withstand around 250 deg F and cure at 400 deg F. To coat the turbine side I will be using Eastwood High Temp Paint which is rated to 1200 deg F. As soon as you decide that you will be taking your turbo apart, it's a good idea to pick up a turbo rebuild kit. Most of the kits include gaskets, bearings, and any other parts that may commonly wear out.
The first step of the process is to completely disassemble the turbo. Not only this will allow you to clean off all the dirt, it also separates any pieces which are bolted together. If you apply powder over two surfaces that are bolted together, it will make it difficult to separate them in the future without destroying the powder. If your rebuild kit does not come with extra hardware make sure to keep track of all the tiny bolts and other parts.
Now that I have the turbo completely taken apart I set aside everything but the two halves of the compressor. They are the only parts that I will be powder coating. I first sprayed them down with Chassis Clean to remove as much of the heavy grease and dirt that was visible on the surface.
To prep the compressor housing for media blasting, I taped off all of the areas that I didn't want the media to get in. It's a good idea to first stuff the compressor housing with clean rags to reduce further damage if the tape happens to fail. The areas taped included machined surfaces, threaded holes, and the entire inner face.
As an extra safety precaution I stuffed a clean rag on the inside of the housing before taping and putting it in the cabinet to be blasted. Even though these areas were taped, I still took my time and avoided pointing the blasting nozzle directly at the tape edge. Glass bead is known to be on the gentler side, but still could have easily peeled up a corner.
I chose to use glass bead because it won't damage the cast aluminium surface. With the turbo out of the blaster I used an air blow gun to remove any media that was still left on the surface and removed the tape and rag. No matter how much effort you put into taping of the parts, it's nearly impossible to not have a very small amount of media passes through the tape. Therefore, it's important to take extra time to make sure all areas are free of any remaining media. The last thing you want is blast media ending up inside your engine. I wiped the turbo down with Pre Painting Prep to remove any chemical contaminants still on the surface.
You may think this is a lot of effort just in cleaning before applying the powder, but you definitely don't want to take any shortcuts. Powder is much more durable than paint but this higher durability does require that the parts be completely free of all contaminants. The next step is to preheat your oven to 410 deg F to outgas the pieces. Outgassing is a method used to remove any contaminants that still remain on the surface of the parts. Heating them above the cure temp will allow the contaminants to burn off before the powder even touches them. The size and thickness of the part will determine how long to outgas, but 10 minutes is a good average. Make sure you use an infrared thermometer to see when the ENTIRE part reaches a surface temp of 410 deg F before it is removed from oven.
Allow the parts to fully cool and wash them down again with Pre Painting Prep as the final preparation step before applying powder. You should wear nitrile gloves during the final cleaning because the oils on your hands could affect the outcome of the powder. With the parts washed again I taped off all of the openings with High Temp Masking Tape. I used aluminium foil to cover the inside faces and Eastwood Paint and Powder Coating stand to hold the oven trays in place while mounting the turbo pieces and applying the powder using Hotcoat Powder Coating gun (You can use either standard or dual voltage). The stand is nice because it holds the oven tray in the same orientation as when it goes into the oven, making it very easy to transfer to the oven itself.
Due to the way our workshop is set up, I was able to put the paint and powder rack on top of a folding welding table in order to take full advantage of our filtered spray booth. Because many of you may not have access to a system like this, it’s recommended that you apply powder in a well ventilated area with the use of a standard dusk mask. Powder Coating does not require the use of an activated charcoal respirator like painting does, but it will work just as well if that's all you have.
The powder colour I chose for the compressor side of the turbo is Eastwood Mirror Black, which will give the turbo a very glossy black finish (Jet Black from Frost Restoration is also glossy finish). I coated the parts and put them in the oven to cure for 20 minutes. The 20 minute cure time is not from the time you put them into the oven, rather the time once the powder flows out. You will able to tell when it flows out because the surface of the part will become smooth, it is from this point the 20 minutes begin.
Now that the compressor housing is powder coated it's time to move on to the turbine housing. Like I mentioned before, I'll be using Eastwood High Temperature Paint for the turbine and centre section, it will give the turbo high heat durability and a good contrast from the mirror black on the other side.
There was a good amount of surface rust on the exhaust side so it too must be media blasted before painting. Before blasting, I used a small wire brush to remove any loose rust or dirt. This will make it easier to blast and remove the risk of any loose rust clogging the air hose.
Just like the compressor housing I taped off all of the openings with masking tape so no media would get in. When blasting, make sure not to direct the nozzle directly at the tape edge because the tape may start to peel.
Before removing the tape, I made sure to blow off any loose media that was still on the surface. I then removed the tape and wiped everything down with PRE.
Using some scraps of metal, I made a stand that would support the turbine housing vertical allowing me to paint every area without touching it.
I put on nitrile gloves again because skin oils can contaminate the metal causing poor adhesion. Using the foam brushes included in the kit I applied the High Temp Coating. The kit comes with different size brushes so you will easily be able to find one that will work well with the part you are coating.
I let it dry to the touch which will take about 30-40 minutes, The High Temperature Coating does not fully cure until it is put on the car and heated up by the exhaust.
Leaving the turbine housing on the stand, I reassembled the turbo using the parts from the rebuild kit. If you don't remember exactly how it goes back together, try and find instructions online. Turbos have very tight tolerances and even if one part is missing or out of place it could cause damage to the turbo or your engine.
Side by side you would never know that this is the same turbo, and that all could easily be done in your garage at a fraction of the price it would take to get done professionally.
To learn more about Powder Coating and for more automotive articles, visit our Technical Articles page.
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