POR 15 Hi Temp coating....Fail!

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SquareRoot

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I previously made a Y-Pipe that connected my Hooker manifolds to a single 3 inch system with a Magnaflo high flow convertor. It worked well but with time I discovered a few bugs with it. For one, I used 2-1/2" inch pipe. It sounded like a musical horn. The exhaust pulses kind of echoed inside the pipe. Also, due to the bend radius, I couldn't get it as tight fitting as I wanted. This meant I had to remove the Y-pipe to remove the transmission. So I redid it with 2-1/4" pipe and it is much better. Lets face it, a K20 with a NV4500 rarely sees north of 3500 rpm. The 2-1/2" was overkill. Furthermore, I believe the exhaust gas was cooling fast enough that it affected the convertor and took a long time to get to the temp needed to "light off". So I was able to get the converter closer to the merge collector where it runs hotter. I also decided to try a coating while it was still new and pretty. I tried POR 15 High temp. It says it's guaranteed up to 1200 degrees. The regular POR 15 I've used in the past has been excellent.

Well, I prepped and applied exactly as instructed on the can. I even monitored the temp with my temp gun and shut it off at 400 degrees to cool and cure. It looked great. It lasted a whopping 20-30 minutes! So don't waste your money, it's a solid fail.

The good news is, the system looks great, is easy to assemble (V band and band clamps) and the converter performance is noticeably improved.
 

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Blue Ox

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I previously made a Y-Pipe that connected my Hooker manifolds to a single 3 inch system with a Magnaflo high flow convertor. It worked well but with time I discovered a few bugs with it. For one, I used 2-1/2" inch pipe. It sounded like a musical horn. The exhaust pulses kind of echoed inside the pipe. Also, due to the bend radius, I couldn't get it as tight fitting as I wanted. This meant I had to remove the Y-pipe to remove the transmission. So I redid it with 2-1/4" pipe and it is much better. Lets face it, a K20 with a NV4500 rarely sees north of 3500 rpm. The 2-1/2" was overkill. Furthermore, I believe the exhaust gas was cooling fast enough that it affected the convertor and took a long time to get to the temp needed to "light off". So I was able to get the converter closer to the merge collector where it runs hotter. I also decided to try a coating while it was still new and pretty. I tried POR 15 High temp. It says it's guaranteed up to 1200 degrees. The regular POR 15 I've used in the past has been excellent.

Well, I prepped and applied exactly as instructed on the can. I even monitored the temp with my temp gun and shut it off at 400 degrees to cool and cure. It looked great. It lasted a whopping 20-30 minutes! So don't waste your money, it's a solid fail.

The good news is, the system looks great, is easy to assemble (V band and band clamps) and the converter performance is noticeably improved.

That's so pretty you should have sent it out for ceramic coating.
 

Grit dog

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Damn…
I spray bombed a 20 year old exhaust with that stuff over 2 years ago.
And never got it to the “cure” temp for a good year after painting it.
No prep other than when I pressure washed the chassis.
Now after being driven around for a year not daily but idk, 1000miles maybe it’s starting to rust in a few spots but those were flaky before I sprayed it.
It certainly hasn’t peeled off.
That sucks
 

tobiahr

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I feel the issue is that you didn't first burn off the original coating on the exhaust pipe before you applied the POR so once that heated up and off gassed it just flaked off the POR. Just my opinion but now i want to science it and find out.
 

SquareRoot

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Never heard of it. Are you being serious or you just want to see my neighborhood disappear in smoke?
 

Doppleganger

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Never messed with their high temp stuff as I never had much luck with any paints claiming crazy temps, but I used the manifold gray on cast iron manifolds alot. Only way I could keep it on was to THOROUGHLY stir the sht, THOROUGHLY sandblast the manifold, then THOROUGHLY wipe it down with a degreaser, and then put 2-3 thinner coats on. I would then take it to a machine shop nearby that had a burnoff oven and had him cook it (to cure) at around 300-350F for about 3 hrs. Anything else and it would flake within a week or so of use.
 

Ricko1966

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Never heard of it. Are you being serious or you just want to see my neighborhood disappear in smoke?
Totally serious,I never took pictures but when I needed to do it you had to take the film to get developed. Clean metal headers,sanded bead blasted whatever wipe them down with atf and get them hot they'll smoke like he'll but it will blue the steel. Look on Google I'm sure you can find pics.
 

Ricko1966

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This is a lot smarter than how I used to do it.
I've never used a torch but sure less chance of a fire.
Okay I've got this all messed up,accidentally double posted this one. So rather than being a double post,I tried to post that 2nd link,now they are both up. IDK
 
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Ricko1966

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I only did it on new headers and I just wiped them with atf and started the engine,I wasn't as worried about staring fires when I was younger. I guess this guy isn't afraid of fires either.
 
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squaredeal91

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My only experience with por15 is the chevy orange I bought and painted my big block w/ in 2014. Truck has only gone a few miles since then and several heat cycles. It's still on there and still looks decent I guess lol.
It's better than rattle can. I do still enjoy the smell of burning off paint & gasket materials on a first warmup
 

Steppin Razor

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I have never found POR-15 to be all that great. I have been looking for a solution for high temp coatings for a while, but haven't actually had a part to test product on while I've been looking. I'll have a motorcycle engine coming up, but seeing as how I have to fabricate the motorcycle that goes around it first, it might be a while. I intend to test out this stuff: https://net4sale.com/stove-paint-aerosol-spray-cans . I have never used it and can't vouch or recommend, but it does say it'll withstand 1200deg of consistent heat. They also make an alumnized epoxy repair putty that was featured on Jay Leno's Garage youtube channel
 

drumvirt

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I feel the issue is that you didn't first burn off the original coating on the exhaust pipe before you applied the POR so once that heated up and off gassed it just flaked off the POR. Just my opinion but now i want to science it and find out.
Having been a paint sales rep who also had to try to solve/settle paint complaints, I think what you say is solid. One of the first things to check on a peeling complaint is to check the substrate side of a peeled chip for signs of a prior coating that delaminated, or for contaminants. Paint manufacturers usually keep "retains" of each manufactured batch for testing in case of complaints. It can either prove the paint was okay, or it can reveal a manufacturing defect. Batch numbers are on the can, like expiration dates on food packaging.
 

drumvirt

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I have never found POR-15 to be all that great. I have been looking for a solution for high temp coatings for a while, but haven't actually had a part to test product on while I've been looking. I'll have a motorcycle engine coming up, but seeing as how I have to fabricate the motorcycle that goes around it first, it might be a while. I intend to test out this stuff: https://net4sale.com/stove-paint-aerosol-spray-cans . I have never used it and can't vouch or recommend, but it does say it'll withstand 1200deg of consistent heat. They also make an alumnized epoxy repair putty that was featured on Jay Leno's Garage youtube channel
There are generally 2 temperature ranges for high temp paints and they sometimes cure at different temperatures. 1200 deg. is the higher end. You may have already checked the specs for the necessary cure temperature for the 1200 deg paint to function properly.
 

bucket

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This is a lot smarter than how I used to do it.
I've never used a torch but sure less chance of a fire.
Okay I've got this all messed up,accidentally double posted this one. So rather than being a double post,I tried to post that 2nd link,now they are both up. IDK

An older fella that I know taught me this about 20 years ago, using a rosebud torch. It works really well.
 

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