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- - OEM Crankshaft Hardening (https://www.evolutionm.net/forums/evo-engine-turbo-drivetrain/732319-oem-crankshaft-hardening.html)

OEM Crankshaft Hardening

I've found conflicting information so far on different sites. Does the OEM Crankshaft get a Nitride or Induction hardening process?

If someone wants to send me cross sections of the crank and rod joirnals of an unground crank, I can provide an answer.

no need. I will bet a million dollars there was no crankshaft hardening on any 7 bolt crank that mitsubishi made. this includes all cranks from 1993 to 2006. I have seen them all. any conflicting info you read is just plain stupid. I have sent some 40 cranks in for nitriding.

I had a '92 and according to the FSM the crank was nitrided.

92 are 6bolt. and yes they are hardened. and the factory manual states not to grind crank. stating hard layer will be lost. no such warning in 7 bolt manuals

Quote:

Originally Posted by 94AWDcoupe (Post 11656121)

92 are 6bolt. and yes they are hardened. and the factory manual states not to grind crank. stating hard layer will be lost. no such warning in 7 bolt manuals

Okay, no million dollars. :crap:

Actually, the DSM's had an engine swap sometime during the '92 year from six bolt to seven. Mitsu specified different oil filters for the two engines which caused much confusion. Also, when I ordered a clutch/flywheel combination I was sent a seven bolt flywheel which I tried unsuccessfully to bolt up. I count one, two, three, many.

Anyway, as we both agree, the FSM for that year stated hardened crank. So what about the '92 seven bolts?

I sent my 7 bolt 4G64 crank to get nitrided.

Quote:

Originally Posted by barneyb (Post 11656167)

I am like 95% certain that the 7 bolt crankshaft is induction hardened from the factory. Talking to several performance shops this is the concensus. Also from a manufacturing stand point it makes more sense to go with Induction as it is a cheaper yet reliable hardening method as opposed to nitriding which is a much more involved process (still reliable). Induction hardening typically has a deeper permeation as well. I guess we will never know for sure unless someone directly involved with the OEM crankshaft manufacturing chims in.

Quote:

Originally Posted by ladiesman285 (Post 11656225)

you would be 100 percent wrong and the performance shops you are talking to are not performance shops. they shouldnt be in business. they are not hardened. what part of "I have seen them all" did you not get? as simple file test will show if a crank is hardened or not. a file easily digs into an unhardened crank. and it slides over a hardened crank.

I have rebuilt every 4g63 out from 89-2006.

unbelievable the ignorance on forums that get passed around like knowledge. if you want to believe for some strange reason 7 bolts cranks are hardened have at it. I am done here.

Quote:

Originally Posted by ladiesman285 (Post 11656225)

I believe 94AWDCoupe, but if anyone else is in doubt, no need for someone from Mitsu to chime in. Someone send me a slice of the rod and crank journals of a trashed crank, and I can post a hardness profile from surface to the interior within a few days.

Quote:

Originally Posted by mrfred (Post 11656366)

Must be nice to science for a living lol

Quote:

Originally Posted by letsgetthisdone (Post 11656377)

Must be nice to science for a living lol

Science can be pretty fun. Tons of daily bureaucracy though.

So this thread from 2011 has some information regarding a turned crankshaft that I got information from. https://www.evolutionm.net/forums/ev...ed-test-3.html

Here is one of the tests an evo colleague in Germany did.

Quote:

We did grind a crank down all the way to determine the deep of the hardening.
The hardening is not nitrite, its inductive hardening ( thats the reason why you can polish the crank.
It was an used Evo8 crank with an rod bearing failure on cyl.1, which was trash anyway due to the failure
We started to grind the number 2 Rod surface.
ALL dimensions in metric (mm) here. Hardness is not an absolute value in our case, its relative measurement!!

Initial : 47.993mm Fillet depth: 0.49mm Hardness: 88
1st grind : 47.893mm Fillet depth: 0.39mm Hardness: 88
2st grind : 47.743mm Fillet depth: 0.24mm Hardness: 88
3st grind : 47.493mm Fillet depth: none Hardness: 86
4st grind : 47.243mm Fillet depth: none Hardness: 84
5st grind : 46.993mm Fillet depth: none Hardness: 68 hardness drops fast

So , in conclusion, you can grind the Crank Rod pin ( only rod testet ) down.
so, 0.25 mm is possible when the fillets should be there and 0.50 mm if fillet doesnt matter or can be refreshed.
Any more does not make it because fillets gone and also hardening drops ( extreme loss after the -0.75 grind )
Also, the grinding should be done in an really smooth way, so it should not be done like an V8 crank. There should be removed only a small amount of material, with cool down times in between. The hardening can change extreme if to much heat is transfered into the crank. ( tried that at Rod position 3, more material in one grind, hardening changes 5 more point than rod 2 )

But, there is an other problem you will run into.
All Bearing manufacturers doesn't make the right bearings for the turbo application.
The max grind to get Turbo bearings is -0.25mm. smaller to get bearings from them.The bigger OS will be only for the N/A 4g63 / 4G64.
This was approved from King bearings, the materials and coats used will be different than and they do not advise to use in high HP applications.
Same Information from Clevite, ACL and Glyco.
Also, Mitsubishi has different bearings ( but same dimensions ) for the 4g63T and 4g63 n/a Engines.

It may be possible that someone has get Bearings as an custom order, but not "off the shelf".

For my self: For an almost stock Evo ( stock turbo ) i would use an g rinded crank (-0.25) when an new one is not in the price range..
In any high HP application ( 500++) i would never used an grind crank.
Get an new or good used one. Better safe then sorry.

here in Germany, its easier and cheaper to use an new crank all time, because the grinding is expensive. Grinding all 4 rod sections is about 500$.
In the states, i assume, it will be much cheaper because you have more Engine shops then here in Europe.

Quote:

I have a scratched up Evo 8 crankshaft that I can sacrifice in the name of science. Might take me a while to get around to it though.

Quote:

Originally Posted by ladiesman285 (Post 11656622)

I have a scratched up Evo 8 crankshaft that I can sacrifice in the name of science. Might take me a while to get around to it though.

Sounds like Evo cranks may be induction hardened afterall, but I'm still game to confirm. If its easier, send me the entire crank, and I'll chop it up. Alternatively, I wonder if English Racing has one. Would be interesting to compare to a 4G64 crank, and I'm sure they have a few cracked ones.