Crank question.....Which one
Thread Starter
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More Turbo
Joined: Feb 2004
Posts: 739
Likes: 11
From: Westfield, North Carolina
Crank question.....Which one
Well the more I thought about it the more Ive decided to pull the 390 back outta my car and go with a different crank. Right now its a .10 undersized 2U crank. Im trying to decide between a 391Ft crank since Ill probably be using a healthy dose of No2 to hit a decent HP number, or a 428 Crank to give me some more Cubes to work with. I already have everything minus the intake {cant decide weather to run a Dual Quad medium riser, or an RPM} the dizzy,balancer,and carb. Was aiming for 450hp but i think im gonna be close to 420, unless I can do sumthing in the bottom in this go round. 
Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
When you up the displacement, you dont increase hp, you just increase torque. I think if you're looking for more strength the way to go is the FT 391 crank. Those suckers are bulletproof. Of course, get it internally balanced and the crank snout turned down and all that jazz. I'm going to assume that you have a decent set of forged pistons. If so, pour on the N2O!
I honestly think the stock cast 390 crank will be good up to a 200hp nitrous shot. More and you might be pushing it. FWIW, a 428 crank will be slightly weaker than a 390 crank, due to it's longer stroke. If you wanted the strength and more cubes, a scat 428 crank or a scat stroker crank may be the way to go.
I honestly think the stock cast 390 crank will be good up to a 200hp nitrous shot. More and you might be pushing it. FWIW, a 428 crank will be slightly weaker than a 390 crank, due to it's longer stroke. If you wanted the strength and more cubes, a scat 428 crank or a scat stroker crank may be the way to go.
Thread Starter
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More Turbo
Joined: Feb 2004
Posts: 739
Likes: 11
From: Westfield, North Carolina
Yeah I have the Trw's, and early model 427 Rods, all ARP bolts. Im having to pull the engine because I dont think it is balanced right , so I figure while its out I might as well drop in sumthing better if I can, besides it wont take to long anyways.
Elder User
Joined: Sep 2003
Posts: 794
Likes: 1
From: Portland, OR
Go with a stock 390 cast crank. You won't break it. Any old regular production detroit forged crank you find is likely no better than the cast crank you have now. These cranks were forged using inferior methods and they sure as heck were never 4340. The cranks were forged flat and had their throws twisted into place. Under hard use they try to return to their original shape. Not good. I've seen factory cast cranks run 8000 rpm and over 600 horse with no issues whatsoever after 10K street/strip miles. Also seen stock forged chev cranks fail when they shouldn't and cheap import junk cranks like Eagle fail where a real racing crank would last a lifetime. Nodular iron is very tough stuff. How many new carmakers use steel cranks?
Lead Driver
Joined: Jan 2003
Posts: 9,893
Likes: 12
From: Ohio
Steel cranks are more expensive to manufacture. Plus the fact that NO one makes a motor with enough power to need it. They don't build 400+ ci motors anymore. Buzzin' little 6's is about standard anymore. Any cast crank can withstand 5000 rpm in a street car. Most factory rev limiters don't allow high rpms anymore.
