I've been looking at a set of asp pulleys that are black nitride steel and a set of march pulleys that are black powdercoated steel. What is the difference and which would be better? Also, what did the factory use to coat the stock pulleys with; just paint?

 

whoa, you are talking about to different things. nitide is used for strenght where powder coating is apperence. nitride is a way to make the metal stronger. powder coating bakes a layer of color on to the metal for apperence only.

 

so ure saying the black nitride pulleys actually have no coating at all and the black color just comes from the nitride mixed in with the steel?

 

Nitriding is a process this puts a hardened skin surface onto the metal surface. The surface hardness is at its best for about .008"and then gets progressively softer. Its excellent for wear.

 

no im saying that in the specific description that you are looking at on their web site does not include the process that they are using to coat the underdrive pulleys black. nitride does not make the steel black, it is only a process in which the steel is superheating until it is white and then quickely cooled down to make the steel better resiliant against stress.

 

powder coating isn't only for apperance. It puts a protective shell on the parts theat prevents rust, scratches and dings (to some extent).

 

i just called asp pulley, first off, let me comment on how stupid i thought their tech people where. they transfered me twice and the guy still didnt know exactly how the color is put on the pulley except that the nitirde makes the steel black??? that i found odd, but i guess you learn something new everyday. im still curious as of two how the nitride process makes the steel black without any addatives, but it seems the black is actually backed into the steel whereas the powdercoating is only layered onto the steel; so i would think that the asp pulley are actually better.

also, for refernece, the aluminum pulleys by asp are anonized black. he also said that with the underdrive pulleys that the alternator will not put out enough current to charge battery at idle. <- just something good to know if you are going to sit at idle for awhile listening to music.

 

and he is right, i have an 89 iroc and have had both sets fo pulleies. i like the March pulleis better for one reason. They don't kill my battery and with a system drawing about 50amps all the time i can't have my alternator not properly working.

 

Are the stock pulleys steel and what are they coated with?

 

when i sprayed most of my engine components with carb cleaner the color came off so i would have to guess paint. by the way, no one tell me i dont know what im doing, i meant for the crap to come off, im cleaning the whole engine bay up.