Deantec

Hopping to get the air intake Powder Coated over the next couple of weeks found the great write up from ED on the s4 intake and valve covers was looking for the same kind of information on the s3 intake, What area's not to get coated and any spacial instructions to the people coating them.
Dean

4drgl

Make sure the powdercoater tapes / plugs all the bolts holes, possibly standing there and marking them with the powdercoater.

Then wash the intake out as many times as it takes to make you comfortable that there's no blast media left inside the manifold... I used a bottle brush and soapy water, washed each piece about 4 or 5 times.

davek9

You need to be real careful if your going to PC the Inside of the cam covers, making sure that no blast media is stuck in the many places in there. I've seen it recommended here not to do it.

BC

The guy that painted them suggested vinegar for some cleaning and the reaction with the magnesium. Works great

SMTCapeCod

There's a rennlister specializing in such things if you don't mind shipping for confidence in the product. legend garage, I just bought one of his intakes and the finish is impressive.

waynestrutt

Most aluminium castings are very porous and it is common to have them impregnated with a plastic solution which cures hard, sealing the casting.This includes calipers as well. If you look in the plenum before coating you will see on the surface a plastic looking film.This really should not be removed. The powder coating temperature is minimum 400 F enough to evaporate the plastic and bring back the porosity.Make sure no area is missed by the coater that is not covered by the gaskets, hoses or bolts. Effectively if the impregnated material is compromised you will be relying on the thickness of the powder coating to minimize intake airleaks.

depami

Are you saying a "raw" intake is porous enough to "leak" and allow un-metered intake air?

Lizard928

thats funny right there!

Sorry Wayne, the plastic coating on some newer parts is to give a better surface finish, nothing more.

PC-85-928S

1) MEDIA BLAST PARTS WITH GLASS
MAKE SURE POWDER COATER KNOWS THESE PARTS ARE ALUMINUM/MAGNESIUM ALLOY
2) OUTGAS ALL PARTS
3) ONE COAT PRIME
4) ONE OR TWO COATS COLOR
5) ONE COAT CLEAR
6) CLEAN WELL BEFORE REINSTALLATION

REMEMBER TO APPLY COLOR THROUGH THE ENTIRE CENTER T
APPLY COLOR TO CENTER ENDS OF INTAKE PLENIUMS WHERE THEY CONNECT TO T

waynestrutt

It is very unlikely you will find a raw non impregnated casting .I have purchased thousands of dollars worth in castings over the years,whether aluminum ,stainless, zinc diecast or castiron.Whenever a casting was part of a pump or would be used where porosty would be a problem they were impregnated with plastic.The process is similar to that done to wood to create pressure treated lumber. Recently I purchased a new pump for my 80 and after installing ,it dripped fuel on the shop floor when running.Thinking I had not tighten the new copper rings tight enough I redid them all only to have the same occurrence. I bridged the relay contacts and watched the pump.Fuel oozed directly through the cast end piece crimped in the discharge end . It had not been treated properly to compensate for the porosity. The supplier knew immediatley when I emailed them and they shipped overnight a new pump. They did not ask for the faulty one back as proof ,just took care of my situation professionly. A worn throttle pivot shaft can allow unmetered air to enter the plenum and your engine will be hunting for an idle position.

As for Colin 's remark i have never seen an as cast part with a plastic finish unless you are talking about acrylic painted parts?


Here is an article worth reading
http://westernsealant.com/what_is_impregnation.html

James Rouse

there's no minimum powder coating cure temperature, powder coat can be specifically formulated to cure at lower temperatures but then requires a longer curing time, that said, most generic powder coats do cure at 400f. I have personally seen some cure as low as 300f but on the other end of the scale bridge builders are now using a coat that only cures when exposed directly to flame (spray with powder then go over it with a torch/flamethrower very cool but wicked scary )