Powder Coating VS Heat Retention

[dagored]

I have heard several differing takes. Some folks say that powder coating engine parts such as heads, cylinders and cases prevents these components from releasing heat. Has anyone here done any real temperature comparisons on painted vs raw vs powder coated motor surfaces ?
John

[crash]

just my two cents ,i would not paint or powder coat the head but everything else is fair game

[yamaman]

Well, I've no idea on actual powder coating compared to paint. But I've never seen a white radiator! And rare these days to have anything but black..

You might find this interesting:

http://www.newton.dep.anl.gov/askasc...9/eng99320.htm

[inxs]

- you might find some basic info here...you want thermosetting resins applications

- Dupont Technical Guide

- delta industries powder basics

- sqipc engine coating

- powdercoating services The powder process/Properties and selection

- pfonline articles

- wacker-silicone resins

[jay760]

you could get really technical and say what colours retain the most heat, how thick is the paint, I have never heard of a bike seizing from being too hot from the barrels being painted, I've blown a hole in a piston by carrying a bag on the front forks, that gets the engine pretty hot

[mwzephyr]

Mechanics rule of thumb, I am also a gear head...
If it is air cooled, don't coat it~ temp matters a lot, if it is oil cooled~ coat it lightly, if it is coolant cooled~ coat it lightly.
If it is cast Iron, it won't usually hurt, if it is aluminum it matters a lot, if it is steel it will be ok.

Brass, copper, magnesium should not be powder coated. Aluminum is ok on wheels, rims, body panels, steel is ok, mig welded parts need to have heat proof automotive primer to cover the welded area.

Ceramic coatings work in many instances to protect and reduce heat but it is not for the average guy to do this type of work, usually only for professional racers to my experience.$$$

Zep

[Travis]

Originally Posted by mwzephyr

mig welded parts need to have heat proof automotive primer to cover the welded area.

Care to elaborate on this more? Your talking about painting and not powder coating correct?

[mwzephyr]

Yes.
I am talking about BOTH painting and powdercoating.->
In production I have found that there is usually outgassing that will occur along these welds causing bubbling to occur as the coating is geling in the oven. The gas or expanded air will pierce the coating leaving marking, and penetration, pitting or rippling allowing future corrosion opportunities.
High temp bonding putty, don't remember the name~ made by Dupont, would adhere to properly cleaned surfaces- alum steel etc.- when dried and sanded and cleaned with automotive dust wipe
cloths and denatured alcohol, the powder would not show spoilage on the welding bead areas.
Powders have different gel temperatures and set times from seconds to almost a minute.
There are very expensive automotive gelcoats- wet primer that will work if the powder and pre coat are compatible.
You need a material that will not show heat shrinkage nor burning at high temps avg 350-450*f
The powders melt, flow, gel, then set. They are usually resin composits, with ingredients tailor made to cause certain timings in flow and finish.
There are metalic appearance combinations etc. Certain techniques are used to cause variations. In production heat dwell in the oven and timing are critical to have all parts in a color batch match the last batch. Variance is an issue between lots of powder also. Your powder supplier will usually be happy to help your coater learn specific techniques to acheive consistant results. If you need more specifics, Duponts website will supply info on each and every powder they make. I am not a fan of Dupont persay but they have better customer service help than most by my experience and they provide accurate data.
Each territory has a customer rep. they will be glad to visit on site for most powder purchases over $500.00.
Most platers and blasters have business relationships with powder coaters.
My advice, if the shop seems while not perfectly clean, at least clean and organised and clutter free
and they keep their powder in a cold dry storage place,
then they probably know what they are doing.
Guns and equipment must always be time-consumingly cleaned and maintained to prevent cross color contamination and poor application.

Dirty poorly organised mad scientist/ artist shops are to be avoided. Thats where crap is born and money lost. Not knocking artists but most have clean organised shops and will expect good money.
You want a cheap job, go to walmart and buy spray paint in cans. You want a good job, you will have to pay for it but ask how the price is figured out. A good shop will explain and detail their billing and remember if you pay for the powder upfront, which you may have to, you take the remainder home if you want it for later projects. Powder, stripping services, wash and pretreatment, labor, gas or electricity for ovens, line time and money for artistry...
Ten years ago a charge of 150-200$ for a frame and fork assy if they had come to us fresh from a blasting shop for a single color with 2 coat passes. 500$ was the most charged for a special color blend with mulitple (2-3)colors.
The powder was always charged
seperately to avoid disputes later.
Art work and specialty stuff needs to be negotiated.
Supply a simple pattern schetched out on paper- you are not their only customer and people forget sometimes what was said last week, you and the shop.
Small stuff is usually scheduled to run with similar colored jobs for others.
If the shop has a small batch oven, you might get a better price for small parts, mirror assys, handbrake handles, clutch pedals, fenders etc. If you are having the whole bike done ~do it all at once so the color and tone and finish match.
Once coated it is too late to fix with out more time and labor and money.
Blame yourself if you did not specify what you wanted.
Get a written receipt of the parts supplied and work to be done, that has a company name address and phone number.
Take photos of parts before sent so you can back yourself up if a dispute or problem occurs.
Know your coater,
he may become a lifelong friend,
and you may become a hero to the rest of your buddys for finding a good shop.

Ride hard, ride on.

Zep

[royfisk]

Mechanics rule of thumb, I am also a gear head...
If it is air cooled, don't coat it~ temp matters a lot, if it is oil cooled~ coat it lightly, if it is coolant cooled~ coat it lightly.
If it is cast Iron, it won't usually hurt, if it is aluminum it matters a lot, if it is steel it will be ok.

Brass, copper, magnesium should not be powder coated. Aluminum is ok on wheels, rims, body panels, steel is ok, mig welded parts need to have heat proof automotive primer to cover the welded area.

Ceramic coatings work in many instances to protect and reduce heat but it is not for the average guy to do this type of work, usually only for professional racers to my experience.$$$

Zep

huh all these years I have been pretty lucky I guess and so has yamaha painting both the head and cylinders. I havent personally powdered either but this topic was disscussed @ a swap meet and a custom harley guy claimed that the rear cylinders run approxmatly 20 degrees cooler with flat black powder coating. Huh again air cooled harleys with cast iron cylinders have been painted for how many years now? The modern harleys with sleeved cylinders are coated too.

[Travis]

So Zep, let me see if I have this right, for mig welded steel to be power coated, you're supposed to blast the part, wash and pretreat the part, spray on this "heat proof automotive primer" on all the mig welds, then spray on the powder?

[NoValidTitle]

So does anyone else have info on this? Lots of people say don't paint or powder an air cooled engine but there are TONS out there that have done it without issues. I ordered the big fin cylinder kit from MikesXS and I planned on powdering the whole schebang, head, jugs, case. I'm still paranoid about overheating even with the big fin jugs.

[malloym]

man, you guys are digging way too deep. just paint or powder however you want it.. hell I got 3 coats of POR-15 (super thick stuff) on my ENTIRE engine... bike runs great.. my new triumph is air-cooled and the entire engine is covered is black wrinkle paint.. stop sweating the small stuff..

[Sundie]

NEW new triumph? The ones with an oil cooler?

And i'm unclear why you would use POR-15 (primarily a hard use/anti rust) sealer on your engine... which is aluminum and won't rust... And isn't a high temp paint... And not for aluminum... (you should be using por-20)... (i think i'm channeling XSJohn now...... with all the ellipsis...)

But yeah, the key here is "your mileage may vary". So, sure, you can paint your motor up, and kill it's cooling, and if you don't live in Arizona, you'll probably get away with it. For a while, anyway.

[malloym]

yea, cause I put anti-rust paint on my aluminium engine. hope this brings clarity.... ughh..

http://www.por15.com/ENGINE-ENAMEL/productinfo/EEPA/

and yes, it's good to 700 degrees...


next question?

[Sundie]

How about the oil cooler?

And i was simply uncertain why you'd go to the cost to use a paint mainly known for it's rust inhibition properties on aluminum - especially when it's recommended for use on "porous" materials - which aluminum isn't.

Oh, and i see where the confusion lies. This is what's typically referred to as simply "POR-15". That item is only tested to 140F. What you linked to is "POR-15 Engine Enamel". A good choice for coverage there. I hope that's what you got.

[Thorshammer]

Just my two cents worth I'v used high temp wrinkle black on engines and found that my oil temp stayed the same also head temp stayed the same. I was told it was because the texture finish gave more surface area, I think it really dosn't make a bunch of difference unless you get carried away. By the way all metals are porous to some extent or silicone lube would just wipe off.

[Sundie]

Aluminum, not really. Because aluminum oxidizes immediately upon being exposed to air, but only at the top level, this sort of "seals" it. Which is why it doesn't oxidize, or rust, further.

It's also why it's a bit more complicated than steel/iron to paint effectively. I'm sure at this point someone will say "my paint stayed on my aluminum" and i'll probably point out to them that it will chip off easily and come off in flakes - it only stays on because it holding onto itself, not the work. Or you used a proper etching paint/primer for aluminum. Or you prepped it with harsh abrasive to give the paint something to hold on to.

[cheftay]

so since you're saying that aluminum is a very tough metal to paint effectively what do you think about this combination:

spraying this primer right onto the motor.
http://www.por15.com/SELF-ETCHING-PR...ductinfo/SEPG/

and then finishing with this

http://www.por15.com/ENGINE-ENAMEL/productinfo/EEPA/

or would it be good to just go with this:

http://www.por15.com/ENGINE-PAINTING...ductinfo/EPKA/

thanks!

cheftay

and i'll be going with black and my motor will have an oil cooler