View Full Version : 3sgte stroker crank

10-31-2005, 03:33 AM
I'm planning on dropping a JDM 3sgte soruced from a SW20 Gen III, and was wondering: I found a Jun 92mm stroker kit, but they offer 2 versions of the crank: a milled, and a forged version. Suggestions? Concerns?

10-31-2005, 04:46 AM
I believe milled means it is made from a solid hunk of metal.. most likely CNC'd.. and forged is a cast that they pour the molten metal into... I would think the milled would be better in strength.. it depends on what they add into the molten metal for strength .. who knows.. I'd go with milled though.. it can be more precisely made than forged.

10-31-2005, 04:59 AM
Forged, they actually hammer the molecules of the metal into a denser pattern, milled is CNC milled from billet. As a former CNC machinist, I know the milled crank will be better balanced, and overall better designed, but I'm really curious how it will hold together at higher revs. Since the metal will be less dense (unless they have a dense steel recipe), I'm guessing the journals might be more suceptible to wear...Here's a link to all interested. They quoted me a price of Y600,000, or around $5400USD. http://www.junauto.co.jp/products/cylinderblock-part/crankshaft/3sg.html?en

10-31-2005, 05:01 AM
Well they might be using forged steel and milling the crank out of that?

10-31-2005, 05:04 AM
Also, heres JUN's theory on the milled crank:

10-31-2005, 05:06 AM
AHHH.. Didn't think of that!
SCM440 is used as a material and processing corresponding to the material is performed. It has both strength and lightness by giving heat treatment and a special surface treatment.
Looks to me like it's not. Hard to tell, alot of the site is hard to understand, due to bad translation.

UPDATE: It's not. Forging results in the moleceular structure being 'grown' as a crystal, with the gain of the crystaline stucture running around edges and the like. (Basically, the grain takes the shape of the crank) Forging the billet, then shaping it with cutting tools 'cuts' then ends of the grain structures, rendering the forging process null and void. This raises more questions than answers. Also, from what I can tell, I won't be able to regrind the journals should they become worn due to the surface-hardening treatment.

10-31-2005, 05:32 AM
bad translation and i'm drunk.. heh

10-31-2005, 05:32 PM
Any more suggestions anyone? I find it hard to believe that 47 people viewed this post and only 1 had an opinion in the matter...

10-31-2005, 08:51 PM
I viewed.. I say I have no knowledge in this. It seems quite pricey. I don't know what you're wanting out of your engine. I know ATSracing sells them for like 2 grand. Stroker kits that is.

10-31-2005, 08:58 PM
I'm wanting 600whp out of it, to be quite honest. The price ain't much of a factor..Just like anyone else, however, I don't want to pay upwards of $6000 for something that's going to wear out real quick or fail at the worst possible time due to high stresses. Thanks for the info on the other kit..i'll check it out..

10-31-2005, 09:03 PM
No, it don't really look that good..they are taking a 5s crank (Perosnally, and this is just me, I've not heard good things about the 5s crank) and machining it...it has the feeling of being hacked together.

11-01-2005, 12:07 PM
Where exactly have you heard bad things?
The 5S crank is supposed to be extremely strong. IE as strong as the 3S crank....
So is the JUN kit. Dunno if it's worth 5k or whatever, but JUN has a really good rep.

There are a bunch of MR2 guys with a 5S crank making alot of pwr. Have you asked over there?
Or here?

11-01-2005, 04:29 PM
Maybe I'm thinking of another block style..

11-01-2005, 04:59 PM
I was always thinking that the 5s crank was stronger than the 3s. Don't know why.

11-01-2005, 05:26 PM
I don't, for the life of me, know where I heard it, but after a bit of research, you your posts, I'm sure I heard it wrong..I swear it was in a magazine..

11-01-2005, 06:23 PM
5S isn't any stronger. Maybe a tiny bit weaker? :shrug:

11-01-2005, 06:47 PM
Either way, from what I can tell, no-one has heard or knows of any problems with a milled 3S crank, so I think that's what I'm gonna run. Thanks for the opinions!

11-02-2005, 09:23 PM
if you want a stroker that strong try getting ahold of pat c over on the AT.net board, he is pshing alot of AWHP and if you want 600 I would suggest whatever he is running.

11-03-2005, 04:34 AM
Cool, thanks!!

11-03-2005, 04:41 PM
He is running a JUN, I believe.....
And good luck getting ahold of him. :P