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

[fastblackracing]

Looks fantastic Mike........if you have not already make sure those big 6 point nuts on the rear main cap
let the oil pan position properly.

A few more weeks and I will be getting started on mine....so your post is timely inspiration.

 

[Mike T]

Looks fantastic Mike........if you have not already make sure those big 6 point nuts on the rear main cap
let the oil pan position properly.

Were you in my shop today??? If not we think too much alike!


I'll dig up a photo to answer your question.

 

[Mike T]

Pan mod for studs.

 

[Wahoo]

The pan needs to be clearanced for main studs whenever you use studs?

 

[Mike T]

The pan needs to be clearanced for main studs whenever you use studs?

When using the standard 6 point nuts the passenger side rear will hit the edge of the pan. The twelve points will clear without any changes to the pan.

 

[dank GN]

Here are acouple pics of my crank flexing aftermath. The fritting on the main is pretty severe.

 

[BEATAV8]

I think that the fretting can happen just from making lots of power. sure detonation could do it too, but not necessarily required.

 

[Mike T]

Since I posted this thread there has been news of some that have been running a stock crank beyond the 500-550 HP level where (for me and others) this pattern has shown up on the main bearings. Do any of you really high HP guys running stock cranks have pics of your bearings to share?

 

[Mr.Spool]

Do any of you really high HP guys running stock cranks have pics of your bearings to share?

i might have i would have to look around,but the bearings that came out of mine looked great.looked good enough to be reused but obviously wasnt.

 

[Mike T]

I just cannot comprehend how you're doing that. What type of bearings are you running? I know the trimetal bearings will show any small amount of deflection.

 

[Mr.Spool]

I just cannot comprehend how you're doing that.

RPE.and im not to bad at tuning

 

[TurboBuRick]

What oil clearance are you shooting for? How are you measuring?

 

[Mike T]

I think all of the stockers will flex beyond a certain HP level. Not aware of any treatment or machining process that could eliminate it.

If we're dealing with .0015-.002 bearing clearance and the crank is distorted .001 at the 500 HP or so it will show the pattern we're discussing. This would be most evident in a layered bearing that shows contrast.

My biggest question is does the flex continue to increase as even more power is applied or does it stablize.

 

[TurboBuRick]

I think all of the stockers will flex beyond a certain HP level. Not aware of any treatment or machining process that could eliminate it.

If we're dealing with .0015-.002 bearing clearance and the crank is distorted .001 at the 500 HP or so it will show the pattern we're discussing. This would be most evident in a layered bearing that shows contrast.

My biggest question is does the flex continue to increase as even more power is applied or does it stablize.

Does a rubber band stableize?

 

[Mike T]

I see where you're coming from Rick but if the crank flexed proportionately to power MR. Spool would be eating bearings

 

[Mr.Spool]

if the crank flexed proportionately to power MR. Spool would be eating bearings

and im notthey are the least of my concerns actually.

 

[TurboBuRick]

I see where you're coming from Rick but if the crank flexed proportionately to power MR. Spool would be eating bearings

A whole lot of factors play into it. You are gambling making big power with a stock crank.
The bearing are the least of the worries IMO

 

[Mike T]

Bearing reference was more of an indicator of crank flex. Inspection of the bearings would be the only way to see this. I would consider it equal to reading plugs to see how the tune is.

 

[Mike T]

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.

 

[Mr.Spool]

You are gambling making big power with a stock crank.

i am a gambling man,but the gambling takes place before the race starts.i have never broken a stock crank in any 109,i have had alot of time on a stock crank its proven to be reliable.that too is the least of my worries.