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Cross Drilled Crank

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Cross Drilled Crank

Postby mustangcobra438 » Wed Aug 06, 2014 8:57 pm

Has anyone ever taken a eagle style crank that is cross drilled where oil hole in rod journal is drilled to the center of the main and main oil hole intersects and drilled and taped one of the main holes to make it non cross drilled?
How did it do?
Thanks, matt
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Re: Cross Drilled Crank

Postby mustangcobra438 » Fri Aug 08, 2014 1:09 am

I know it wouldn't make it straight shot oiling but would it be worth it to overcome some centrifugal forces by blocking off one side so that it does not get oil ever 180degrees?
Anyone?
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Re: Cross Drilled Crank

Postby Adger Smith » Fri Aug 08, 2014 1:16 am

Use a 3/4 groove bearing.
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Re: Cross Drilled Crank

Postby Kevin Johnson » Fri Aug 08, 2014 1:52 am

The 3/4 groove bearing will dampen the oil supply flow path reversal pulse for a cross drilled main. If you want an explanation of why this is important when you have aerated oil (small bubbles present) see page 162 of SAE 932785 -- the reversal pulse on 180 degree bearings makes smaller bubbles coalesce into larger ones which is potentially bad for the rod bearings.

Why do you want to re-engineer the drillings beyond the issue of centrifugal force? Did you have a failure or did others have a failure using this particular crankshaft and drilling pattern at your proposed rpm? Note that the centrifugal effects amplify aeration problems -- could this be the underlying problem?
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Re: Cross Drilled Crank

Postby rally » Fri Aug 08, 2014 9:08 am

Cross drilled cranks are no good. Go to Reher and Morrison racing site. They explain why they will never use one and you shouldnt too.
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Re: Cross Drilled Crank

Postby Walter R. Malik » Fri Aug 08, 2014 9:11 am

rally wrote:Cross drilled cranks are no good. Go to Reher and Morrison racing site. They explain why they will never use one and you shouldnt too.



Cross-drilled crankshafts work great at low RPM ... making that kind of blanket statement is just plain wrong.
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Re: Cross Drilled Crank

Postby rally » Fri Aug 08, 2014 9:26 am

Walter R. Malik wrote:
rally wrote:Cross drilled cranks are no good. Go to Reher and Morrison racing site. They explain why they will never use one and you shouldnt too.



Cross-drilled crankshafts work great at low RPM ... making that kind of blanket statement is just plain wrong.

As opposed to a low RPM crank that isnt crossed drilled? If your going to spend some extra money to run a cross drilled crank at low RPMS, why not save yourself some money and not buy a crossed drilled crank. Many performance applications have used a crossed drilled crank. They have failed and ruined bearings because lack of oil supply. I would never use one, low rpm, high rpm. I take Reher and Morrisons advice anyday over yours. They have been the hi perf business for many years. They have done lots of testing on cross drilled cranks. Great knowledgeable people.
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Re: Cross Drilled Crank

Postby Adger Smith » Fri Aug 08, 2014 9:29 am

I agree about doing a blanket statement on crossdrilling. There are many ways to cross drill, some work well at high RPM with the correct oil delivery system, others don't. There are X drilling, modified X drilling, Y drilled, Thru drilling, ect patterns of crossdrilling. A blanket statement of no good is just like saying a size 12 shoe is no good. It isn't any good if you are trying to put a size 14 foot or size 7 foot in them, but work well in the right application. It is just Fluid dynamics 101.
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Re: Cross Drilled Crank

Postby Warp Speed » Fri Aug 08, 2014 9:40 am

Walter R. Malik wrote:
rally wrote:Cross drilled cranks are no good. Go to Reher and Morrison racing site. They explain why they will never use one and you shouldnt too.



Cross-drilled crankshafts work great at low RPM ... making that kind of blanket statement is just plain wrong.

Maybe for a 2000rpm diesel........
Otherwise his statement is spot on!
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Re: Cross Drilled Crank

Postby pamotorman » Fri Aug 08, 2014 10:19 am

I have build 7500 RPM BBC drag engines with crossed drilled cranks with no problems. they must be talking about much higher RPMs
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Re: Cross Drilled Crank

Postby pamotorman » Fri Aug 08, 2014 10:22 am

Warp Speed wrote:
Walter R. Malik wrote:
rally wrote:Cross drilled cranks are no good. Go to Reher and Morrison racing site. They explain why they will never use one and you shouldnt too.



Cross-drilled crankshafts work great at low RPM ... making that kind of blanket statement is just plain wrong.

Maybe for a 2000rpm diesel........
Otherwise his statement is spot on!

chevy sold a lot of big blocks with cross drilled cranks that did not blow up. every HP BBC had a cross drilled crank
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Re: Cross Drilled Crank

Postby Warp Speed » Fri Aug 08, 2014 10:41 am

pamotorman wrote:chevy sold a lot of big blocks with cross drilled cranks that did not blow up. every HP BBC had a cross drilled crank

How many do they make now?
How many current performance engine designs use them?
Same goes for the 3/4 groove bearings mentioned earlier?
Those two are a perfect make up for a slobbering, inefficient oiling system.
This is the 21st century! LOL
Will a cross drilled crank guarantee a failure? Probably not, but why use one when it is a known FACT that they cause big problems and inefficiencies in the oiling system?
Kinda like using a fluid damper............why would you?
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Re: Cross Drilled Crank

Postby miniv8 » Fri Aug 08, 2014 11:39 am

The thread is not about whether or not crossdrilling benefits engines at any RPM.

Consider using a plug instead of thread.

The path of least resistance is using a grooved bearing as mentioned earlier.
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Re: Cross Drilled Crank

Postby rally » Fri Aug 08, 2014 12:35 pm

miniv8 wrote:The thread is not about whether or not crossdrilling benefits engines at any RPM.

Consider using a plug instead of thread.

The path of least resistance is using a grooved bearing as mentioned earlier.

Well to me it is about a cross drilled crank. You dont need all that trouble using one, when you can buy a crank thats not cross drilled. Less headaches.
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Re: Cross Drilled Crank

Postby pamotorman » Fri Aug 08, 2014 12:48 pm

Warp Speed wrote:
pamotorman wrote:chevy sold a lot of big blocks with cross drilled cranks that did not blow up. every HP BBC had a cross drilled crank

How many do they make now?
How many current performance engine designs use them?
Same goes for the 3/4 groove bearings mentioned earlier?
Those two are a perfect make up for a slobbering, inefficient oiling system.
This is the 21st century! LOL
Will a cross drilled crank guarantee a failure? Probably not, but why use one when it is a known FACT that they cause big problems and inefficiencies in the oiling system?
Kinda like using a fluid damper............why would you?

i read this article, In a cross-drilled crankshaft, oil feed holes are drilled completely through the main journals so the passages are open on both ends. Holes from the rod journals are then drilled at an angle to intersect the holes in the main journals at the centerline of the crank. the difference is that the chevy cranks rod journals are not pressurized from the centerline of the main journal as the oil passage to the rods is fed from the outside edge of the mains not the center. maybe this is the difference as I have built 1100 HP supercharged boat engines using chevy cranks that were crossed drilled and no problems
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