Nitrate coating on crankshaft - how important?

[lacroixdp]

I know there was a discussion not too long ago advising against turning a crank due to the fact that the nitrate coating will be eliminated. I am fairly new to this particular engine; I come from a German car mechanic background. I haven't ever heard of a negative effect from turning a crankshaft and not reapplying a nitrate coating, but I haven't ever dealt with a engine this small turning this much horsepower, and lord knows I'm not a professional with 4G63's ^^ Could people that have had good/bad experiences please reply to this so I can get a better idea of what the effects from grinding the crank would be? The car will be producing around the neighborhood of 350-375FT/LB of torque. Thank you again for all your help!

 

[1995badgsx]

gotta have it
without it the crank and bearing will not last under good power or alot of boost

 

[al5dsm]

Well said.. i have first hand experience with this... 112 miles.. and a spun rod bearing

 

[GSX Lady]

I was wondering the same thing, because my machine shop sent my crank to be turned because it was slightly ovaled.
I questioned the manager about that, he said that it was only turned enough to need the next oversized bearings and the hardening goes deeper than that.
Is the nitrate a hardening process or is it just a coating?
Should I get a new crank or what?

 

[lacroixdp]

Alright, sounds like the safest bet is to have a nitrated crank. I know that it is possible to have this done after your crank is turned; does anybody know of a good company that sells crank kits that already have been renitrated? If no, does anybody have a good reference on a company that would turn and nitrate my current crank? Thanks!

 

[Defiant]

Okay, step one: it's not "nitrating". That's for fertilizing, such as sprinkling chicken shit on the petunia beds. The process is "nitriding" and it's not a "coating" but an infiltration on a molecular level. In ascending order of detail, it goes like this:

http://metals.about.com/library/bldef-Nitriding.htm

http://www.matter.org.uk/steelmatter/manufacturing/surface_hardness/7_2_4.html

http://www.key-to-steel.com/Articles/Art117.htm

I don't know how deep in goes into a Mits crank, nor do I know if it can be re-treated (such as the case-hardening of camshaft lobes can be). But it's not something you want to compromise.

 

[1995badgsx]

it also sometimes bends the crankshaft and it has to be straightened sometimes, reason being it is a high heat process

 

[lacroixdp]

That's exactly what I needed. Thanks!