Ok I am doing a 2.1 stroker build. ej25 crank in a ej20 case w/ custom pistons. I plan on revving to 8k. I have a 2008 sti crankshaft "370" It has one rod journal that has been wiped .020. So it will need to be ground and I found ACL oversized bearings I can use that are .75mm over ~ .029 inch. I am wondering if it is neccesarry to have that crankshaft re-hardend after being ground? The cost is $185 for hardening. According to this website, qoute "In most cases, a stock OEM steel forged crankshaft can be welded and/or ground then installed without concern. The induction hardening process has a significant depth, and on non welded journals will remain after being ground." http://www.crankshaftco.com/steel-crankshaft-hardening.html Is rehardening really neccesary, this crankshaft is not the nitrided one...? Balancing Internals::: The shop does recomend balancing. I understand the importance of this, especially since it is a custom build. Balancing the crank, pistons, rods => $200 Balancing the flywheel is => $50 ( I plan on using the stock WRX flywheel.) Lastly radiusing the oil holes on the crankshaft to help with oiling => $50 I am trying to do this as inexpensively as possible. Where can I skimp or is all of this neccesary? Thank you! I apologize if I was vague and can try to clarify.
I would assume that the process to make a crankshaft would be no different than any other precision hardened steel component. Heat treating is done prior to grinding because heat treating causes distortion in the material. From my experience in tool making there should be no need to have it hardened after grinding as it is already hard. That is my .02. Good luck with the build!
Because their hardening process has 'significant depth', you would not need to re-harden after being ground. Also, IIRC, only the JDM STI crankshafts were forged, not the USDM STI crankshafts.... could be wrong on that one, but that is what I thought. I would have the rotating assembly balanced with the flywheel (after being ground). And I thought the oil feed holes were already ovalized at the edge, no? Are you certain that your crank is nitrited? ~Dan
AFAIK, all EJ internals (except pistons) are forged. I don't know much about a build like this, but the fact that you're using the word "skimp" at all makes me nervous. So proceed with caution. that is the kind of attitude that frequently ends in failure. You're always walking a fine line with a hybrid build, especially a stroker, do not skimp. If something is not necessary, save the money. That's the way to approach this. That said, I know that revving a subaru to high-rpms leads to oiling problems. the longer stroke amplifies this. I don't know much about radiusing the oil passages, but any genuine improvements will be a good thing.
Well I am fairly confident this is not a nitrited crankshaft. At least that is what the previous owner told me, he was upgrading to the nitrided crankshaft. So that would mean it is induction hardened. And according to Crankshaft Company it is not necessary to reharden an induction hardened crankshaft after grinding or welding. So far I think oil passage radiusing, internal balancing w/the flywheel will sufficent but the hardening may not be.
You may want to deal with Crankshaft Supply Company, Located off Washington. They do most of their work in house and have very good turn around times. I have been using them for 15+ years for stuff from stock crank repair to custom stroker cranks. Personally I would rather deal with a local company in person VS phone/email one picked off the web.
Yes crankshaft supply does do good work. I have been dealing with Guy at DG motors. He is the one who has priced everything out for me... I will have to call crankshaft Su. and see what their rates are... I know most machine shops prefer to do the machining if they are going to be assemblyin the motor.
