Is this what crank twist does to the mains? (update)

[No disintegrations]

From what I can tell when it happens the crank tends to ride the outer edge of the bearings. Seems like it would be difficult to maintain the oil wedge in those areas.

Maybe the crank is not straight or was machined improperly? Or somehow was bent?

 

[Mike T]

Bad machine work on a crank will show up as a 360 degree pattern on the bearings. Only possible explanation for a diagonal pattern is improper cap alignment.

 

[Mr.Spool]

you can get away with a certain attention to detail 80/100hp per hole,start moving to 125/150hp per hole its whole different ball game.

 

[No disintegrations]

Bad machine work on a crank will show up as a 360 degree pattern on the bearings. Only possible explanation for a diagonal pattern is improper cap alignment.

You seemed to be asking for ideas, so I gave some.

 

[Mike T]

You seemed to be asking for ideas, so I gave some.

Sorry if that came across as blunt. I really am focusing more on what is happening to the crank itself. Actually I'm leaning towards it being torsional forces twisting the crank rather than some sort of oscillation. And yes I am fishing for thoughts on this. In particular getting the High horsepower guys to show some bearings.

 

[No disintegrations]

Sorry if that came across as blunt. I really am focusing more on what is happening to the crank itself. Actually I'm leaning towards it being torsional forces twisting the crank rather than some sort of oscillation. And yes I am fishing for thoughts on this. In particular getting the High horsepower guys to show some bearings.

Its cool. If I missed it how much power you making?

 

[Mike T]

That crank may have seen 550 at the flywheel. The motor now has a forged crank in it and is making more power.

No reason to get back into the motor right now but I'm willing to bet that the bearings will not show the odd wear pattern.

 

[turbo89]

That crank may have seen 550 at the flywheel. The motor now has a forged crank in it and is making more power.

No reason to get back into the motor right now but I'm willing to bet that the bearings will not show the odd wear pattern.

Learned long ago .. can a stock crank live in 750 hp .. sure it can..
how long ? nobody knows ...

Do you feel like gambling ? some guys will and they win.. others try and loose ..

there are no buried secrets here.. I've had cast cranks on 650 hp setups with perfect tunes.. but yet the bearings and caps get pounded .. why ?? Crank flex ..

Its all on how you look at it .. for anything over 500 hp I don't bother with a cast stock crank unless its a disposable motor.
for $450 + machining its just not worth thinking about crank walk.

 

[Mr.Spool]

In particular getting the High horsepower guys to show some bearings.

thats just going to show you a small piece.i have no agenda on this board.if you feel good with a forged crank go ahead its your stuff,i dont push anyone to do xy or z but dont think for a second that the crank is the limitation to these motors as i and others have and can take a stock crank or forged crank to the limits of the block.i dont think alot of guys can build a 109 for 125+hp per hole nor can tune for it.

 

[Chuck Leeper]

but dont think for a second that the crank is the limitation to these motors

Pretty much what Jim Ruggles told me, 20+ yrs ago.
I asked about longevity, and his comment was, "the block can last a while, @ 600FW". The crank, longer, if the tune is spot on.
I then asked about a girdle. He said, "it may delay the inevitable, but isn't worth the $$". {He had already done that trick.}
He also mentioned a "trick', that the Sunnen rep passed on to him. Due to the short length of the block, line honing can be a problem, w/ the end bores getting oversized. He didn't elaborate..

 

[Mr.Spool]

mine went 7 years never left the garage under 850hp.stock crank came out and magged good.we didint use it because of the amount of hits and cycles it had and i had another stock crank from an original motor i could use.that one went in the new block and that motor has already seen 800hp.inmo when going over 800/900hp the cylinder walls will develope small cracks from repeated cylinder pressure over time and that is the limit if the motor is built right and tuned right.

 

[turbo89]

mine went 7 years never left the garage under 850hp.stock crank came out and magged good.we didint use it because of the amount of hits and cycles it had and i had another stock crank from an original motor i could use.that one went in the new block and that motor has already seen 800hp.inmo when going over 800/900hp the cylinder walls will develope small cracks from repeated cylinder pressure over time and that is the limit if the motor is built right and tuned right.

Do you have anymore of these "MAGIC" stock cranks one can purchase ?

Because regardless of what one does to the holding structure.. the CAST cranks still MOVE... especially anything over 650 hp
regardless that the tune is spot on...

I can see running a stocker up until 650 if your brave ... but @ 850 .. that's no longer bravery ..

 

[Mr.Spool]

Do you have anymore of these "MAGIC" stock cranks one can purchase ?

actually i have the one that came out of the last motor now sitting in a box.think you have what it takes to break it

 

[Mr.Spool]

I can see running a stocker up until 650 if your brave ... but @ 850 .. that's no longer bravery ..

perhaps i have the right builder.many guys build a 109 but some build them alot tougher.

 

[Mr.Spool]

the CAST cranks still MOVE... especially anything over 650 hp
regardless that the tune is spot on...

its not the only thing moving around my friend.i must say i have alot of tuning time on 109 alot went into getting the right tune.alot more than most would even consider.saying spot on sounds like an easy dismissal for something that took alot of r/d and in my opinion contributes highly to the power made and how it lives.