Crank ????

[3.8L V-8 eater]

Well I dropped off my motor to the machine shop to have the cylinders honed new rings etc... The crank has been turned .010 already and due to the #1 journal being a coupe thou to small it appears I'm screwed :frown: So, I guess my question would be how many have taken the risk to have the crank turned another .010?? What power levels have showed to break cranks?? And also does anyone even sell bearings for a turbo crank for.020 under???

Thanks!!!

 

[QUIP'6']

Well I dropped off my motor to the machine shop to have the cylinders honed new rings etc... The crank has been turned .010 already and due to the #1 journal being a coupe thou to small it appears I'm screwed :frown: So, I guess my question would be how many have taken the risk to have the crank turned another .010?? What power levels have showed to break cranks?? And also does anyone even sell bearings for a turbo crank for.020 under???

Thanks!!!

yes especially if you put in steel center caps. yes they do sell .020 under bearings.

 

[hemi8]

Turning 20 under is no big deal, the problem is the cast crank itself: if you want to make power over 500hp. The crankshaft will flex in the middle and the center 2 caps will "walk", billet steel main caps or stock, doesn't matter. A forged crank will not flex, a forged crank and center 2 billet caps is all thats needed for the typical power range of a real fast street car( 500-800hp). Just my 2 cents.
Mike

 

[3.8L V-8 eater]

Turning 20 under is no big deal, the problem is the cast crank itself: if you want to make power over 500hp. The crankshaft will flex in the middle and the center 2 caps will "walk", billet steel main caps or stock, doesn't matter. A forged crank will not flex, a forged crank and center 2 billet caps is all thats needed for the typical power range of a real fast street car( 500-800hp). Just my 2 cents.
Mike

It does have billet mains (the 2 centers) So if it is going to walk even with the billet mains then I guess I have no choice but to get another crank :frown:

 

[Clark6]

Turning 20 under is no big deal, the problem is the cast crank itself: if you want to make power over 500hp. The crankshaft will flex in the middle and the center 2 caps will "walk", billet steel main caps or stock, doesn't matter. A forged crank will not flex, a forged crank and center 2 billet caps is all thats needed for the typical power range of a real fast street car( 500-800hp). Just my 2 cents.
Mike

I thought a forged or any crank would flex, just a forged one would be a little more difficult to flex.?

 

[turbodave231]

At the same load, a forged crank will flex less than a cast crank. No crank will tolerate flex very long without failure......main bearings aren't very happy with flex either.

That's why Buick added more structure (4 bolt caps) and better material (billet steel) to the caps on S2 blocks.

Dave

 

[87action]

crank

Basically the stock crank is just that (stock). It's not intended to be hammered with such force(high boost pressures) like what we have been doing with our cars even without detonation it doesn't like it. After putting up with the stock cast crank failures, (balanced or not) you have to move on to a real forging. After running my forged crankshaft ------------- no more problems! FWIW

 

[hemi8]

Don't be to quick to not use your crank, it really depends on how much power you intend to put down. There is always the option of the girdle which is for use with the stock crank to keep it from flexing. All these things are not unique to these engines, this is true of almost any engine that is built for serious power. Going past about 10.80 you enter another zone, and that zone gets to be expensive. Just have to sit down and really think about how far you intend to go. If you build a very stout short block with quality forged internals and good aftermaket heads you can adjust your power level with external only changes ie: Turbo and injector swaps.
Mike