[455-4+1]

So does anyone know ?? Would an aftermarket forged 3.75" stroke be legal in stock/super Stock or are these limited to factory parts ??

Is the RAV 3.75" crank a 3" main deal ???. If theres limited demand for them I supose they will be cheap ??? LOL Anyone have one for sale or any idea on price ??????

[tom s]

V cranks and also 61 SD 389 cranks are 3in mains.They are legal in SS I believe.The last one I saw on ebay went for $1500.Tom

[lugnutt]

How will these cranks compare to the Moldex? As far as stregnth goes. Are they going to be just as good?

[Dragncar]

OK,they are going to be forged in China.I can live with that(sorry old one).But where and who is going to finnish them.Are they going to have all of the issues as the cast ones,barely within specs,thrust bearing problems ect.If we have to spend a bunch of money on them to make them work they had better come in at 1050$.Mongo,I for one will have no problem buying one for 1050$ and making 600HP.If they are the real deal I will buy 2 at that price.Planing on another engine now,only an aftermarket block pump gas vertion now.But with the small ccs on the Tiger and the High Ports I am trying to figure out which stroke to go with.Maybe a 4.00 and build a big bore short stroke high rever.The dish in the pistons can only get so big and work right.

[rumair]

a forged crank done right for under $1500?

i'd be all over a couple of those...

[GOAT8U2]

Good news IF this turns out to be a worthy piece and can stay close to $1000.

But there are only so many Chinese factories doing cranks and at that price this sounds like an Eagle crank. If so, Eagle's getting their Chinese cranks back in pretty good shape ( bunch of engine builders quotes ).

Now if only someone would take the time to make us a single turbo bolt on kit to test out these cranks around the 1000hp mark

[HWYSTR455]

I too would get one of these for a <650hp street engine, (ok, without spray!), because I don't want to have to shop for a crank every time I do a rebuild. I drive the crap out of my street cars, use them as daily drivers, all with 400-462s in them. I usually do a rebuild on each every 3 years or so, or about 120k miles. On the one daily I plan to go IA2, same principle, block shopping is a pain.(and I refuse to go 'corporate'!)...

[White Warrior]

If a 4" stroke forged crank becomes available it would be easy to have it offset ground to 3.75 with a 2" rod journal. I have stroked a couple of 3.75" cranks to 3.875" with good results but going the other way with an offset journal would be a great way to go as you would loose some friction and have a slew of SBC rod bearing choises
I think a 4.31 x 3.75 " combo could make 900 hp N/A with the right heads,like the new KRE High Ports. Would be a piece of cake with Super Chiefs or Tiger heads.

[PONTIAC DUDE]

My 4.5 crank uses a 2.100 rod journal.

and lots of Nitrous. LOL.

[tom s]

Dave,how can you run a 2in chevy rod with a pontiac journal?When I looked to do it they were too narrow so had to use the BBC.Tom

[White Warrior]

You use a BBC rod with a 2" end,they will make them anyway you want

[bobzdar]

Do they make 2" bearings in bbc/pontiac width?

[tom s]

with a custom rod you could also run the 1.88 HiPo bearing and get more offset.Tom

[BVR421]

heres a 3 1/4 stroke for you
http://cgi.ebay.com/ebaymotors/ws/eB...MakeTrack=true

[taff2]

The lack of a reasonably priced forged Pontiac crank over here in the UK is why I'll probably have to change to BBC power when I twin turbo my race car next year. I'm aiming for about 1200hp and I don't see a Pontiac cast crank surviving at that level for long,not to mention the block as well. It's a shame as I've run Pontiac power for about 15 years but I can build a stronger BBC for half the cost of a Pontiac.

[lugnutt]

Originally Posted by lugnutt

How will these cranks compare to the Moldex? As far as stregnth goes. Are they going to be just as good?

[Brian Baker]

Moldex = billet.

Opinions vary, but for all intents and purposes, a forged crank will be just as strong as a billet...and in some instances stronger. With a billet, the grain runs in one direction, and when it is cut, it is done so to minimize weaknesses in certain areas of the crank in relation to the grain flow.

With forgings, the grain does not flow in the same direction.

Think of a wooden baseball bat. We were alway taught to swing it with the label either facing up or down, that way the lines of the woodgrain would run in the same plane as the ball when making contact. Try to hit the ball with the label facing the pitcher as you swing, and you run the risk of cracking the bat, because the ball is contacting it in a 90-degree plane (or perpendicular) to the plane of the woodgrain.

Now compare this with a blow on the rod journal from the piston/rod. It's better to have that grain in the rod fillet and throw area perpendicular to the blow. With a forging, the grain will follow the shape of the forging, whereas with a billet, it runs all in one direction when the ingot or "blank" is made (which is then whittled into a crank). I'm not a metalurgist, and the examples I'm using are greatly simplified, but I think you can still get the gist of it. Others like Tom Vaught could explain it in greater detail.

[Tom Vaught]

Billets are more expensive than forgings basically because the forging allows less time to finish the cranks vs hogging the shape out of a large piece of steel, (Billet).

Brian is correct about the grain flow too.

The billet does allow a vast array of different main/stroke/rod journal sizes vs the forging which will have only so much material in any one direction.

A Forging must have two key ingredients to be successful:

1) Clean steel of the correct material type like 4340.

2) Proper machining of the forging in all dimensions at all parts of the crank and the right oiling scheme to survive high rpm loads.

You get both of those things for your $1100.00 and you have a great part.

JMO

Tom V.

[Skip Fix]

I thought I remember reading an article that since on a billet crank/rod you actual cut across the grain you loose some strength whereas a GOOD forging keeps the grain pattern just changes its directions, so no spots for stress riser to start as in a billet. I'm no metallurgist but that arguement made some sense. Same thing Brian was saying.

[Tom Vaught]

One of the extremely few Carrillo failures I heard about was due to the cap section of the rod grain structure not being 90 degrees to the rod beam when the cap was made. The cap failed due to the grain structure deal.

Tom V.