Cross Drilled Crank

[pamotorman]

how many engine builders here who have run cross drilled cranks had rod bearing failures ?? I have had non what about you other guys ????

[Kevin Johnson]

Cavitations happen when the oil boils or aerates at on the INLET side of the pump causing the pulsations.

When the oil feed to the rod bearings passes the closest approach to the longitudinal axis of the rotating crank, the reaction force of the wall of the passage acts like a pump pushing the oil towards the rod bearing. When the pressure from the engine oil pump is insufficient to supply the opposite side of this closest approach, cavitation in the passageway also occurs.

When the net feed pressure in this zone is declining, dissolved gases will come out of solution in the reverse of their dissolution according to Henry's law. This is also a type of cavitation in that the gas departs from the fluid in a similar way to that of the vapor phase of the neat (unaerated) solution.

There are many possible sources of pulsations in an oil feed. Even with ideal fluids, the pump gear teeth engagement will cause pulsations. This is one of the reasons that the BBC pump uses a greater number of teeth over the SBC. I would cite SAE 750051 again because it explains how this pulsation varies from gear, crescent and geroter pumps but some, apparently, view German pumps as innately different from American pumps, thereby tainting the data.

The pulsation from oil feed path reversal will occur in a cross drilled crank irregardless of the rod feed proximity to the central axis of the crank or the journal surface. The amplitude and waveform will vary of course. When monitoring the oil pressure with sensitive instruments, attention must be paid to any smoothing or damping or filtering of the data.

[Warp Speed]

how many engine builders here who have run cross drilled cranks had rod bearing failures ?? I have had non what about you other guys ????

How many have had failures with a standard, straight shot oiling that was purely due to the strategy used?

How many modern, 90* v-8 performance engines use this cross drilled strategy?
How many are using bearing grooves longer than 180*?

[Kevin Johnson]

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.

Hence the reason I'm wantin to modify one

Be sure to get an answer about indexing of the plug with respect to crank rotation. There will be different fluid dynamics depending on which is chosen. If someone is willing to do the analysis, you might find that particular journals will benefit from one orientation over another.

Just off-hand, I think that your comment about the oil being beaten up in your engine is the first place to start rather than jumping into modifying the middle of the system. The oil in the sump needs some semblance of structured quiescence or isolation (see the primary function of a windage tray) and residence time to release entrained air prior to being drawn into the pump again.

[pamotorman]

how many engine builders here who have run cross drilled cranks had rod bearing failures ?? I have had non what about you other guys ????

How many have had failures with a standard, straight shot oiling that was purely due to the strategy used?

How many modern, 90* v-8 performance engines use this cross drilled strategy?
How many are using bearing grooves longer than 180*?

that is not the question. according to the expert if you use a crossed drilled crank you will certainly have a failure and how many have we had here ??? I even crossed drilled cranks that were not crossed drilled from the factory so that is why I asked how many bottom end failures have we had with crossed drilled cranks. in 20+ years of race engine building I have had none even on a BBC engine with a smashed in the pan that ran and won a 100 lap dirt track race with 30# of oil pressure down from the normal 50#..

[Warp Speed]

how many engine builders here who have run cross drilled cranks had rod bearing failures ?? I have had non what about you other guys ????

How many have had failures with a standard, straight shot oiling that was purely due to the strategy used?

How many modern, 90* v-8 performance engines use this cross drilled strategy?
How many are using bearing grooves longer than 180*?

that is not the question. according to the expert if you use a crossed drilled crank you will certainly have a failure and how many have we had here ??? I even crossed drilled cranks that were not crossed drilled from the factory so that is why I asked how many bottom end failures have we had with crossed drilled cranks. in 20+ years of race engine building I have had none even on a BBC engine with a smashed in the pan that ran and won a 100 lap dirt track race with 30# of oil pressure down from the normal 50#..

They were certainly questions that I asked you!?!
Just was curious why you feel it is superior, and if it is, why isn't it more widely used in performance applications?
I know I have never said you would have certain failure with one, but can it cause unnecessary problems? Most definatly!
I've never had a failure with a cross drilled crank, but then again, I have never used one. Early on just lacked the opportunity I guess. But later in life, I've learned to know better.

Trying to keep it technical, what does cross drilling improve?
What are the main things it cures/improves?

[Belgian1979]

Well this comment on YB says a lot I think :

As for the Chevy BB crankshaft cross drilled 5140 came out because of Nascar racing, i received afew back in the day and they were also made of 1053 cross drilled as well.
With the much better 4340 forging made aftermarket cross drill as well i have ran all of them. Including non cross drilled bbc cranks.
To many other problems have been assocated to running crossdrill cranks and blamed on cross drilling. Yes they are a breed that must use a diff. style of building but they all survive to 9500k and into the 10k area. Drag racing. I build my own engines and some of the problems others blame cross drilling to are

A= Low oil pressure due to not enough Volume of oil. No volume no pressure. Crossdrilled cranks requires more oil to keep up the pressure and a sump of 8 qts, or more. Be it centrifical force throw it off or main bearing cavitation not getting fed by enough oil. High volume oil pump required.
B= main cap walk, and or main cap hole getting distorted under load, caused by 80 pounds out of balance and the usual 5 and 10 gram balance job aint gonna cut it at 8000 plus rpms, trumendious amount of force on the mains.

C= No real race motor esp. BBC ever should use oem main caps period and 98% of people think of a damn good reason to say otherwise but 1" of iron main cap under the crank will only support maybe 7200 rpms at a modest HP level before they start bending downward and take out the main bearings and then rods Hence cap walk . Bolts in hell will stop this. You need a billet steel main cap with a 1.5 inch thick mian cap web at a min. of heat treated 1045 steel 4140 is super. That is needed to keep a 80 piund crank thats flexing and bending at any HP level. So dont blame it on a cross drilled crank when the rest of it isnt ready to do battle.

D = So many ideas have been tried in the past and what doesnt work is fully grooved bearings , half or none at the most. Yes you lose oil wedge. Grooving the crank lost out real fast as well.

E= Motor mounts including steel replacement esp. On a good hooking clutch car and auto chassis are almost right there today being connected to oem frame mounts will pull apart the block at mains 2 and 3 and cause suspected main cap walk, but really caused by block getting pulled apart breifly at the hit long enough to start the lose of them two main bearings and the process has been started. Real High hp cars use motor places which allows crankshaft to spin freely undistorted and live.

F = Oil control , keeping the oil in the bottom with the pick up covered at all times even under decel. Time. Takes 4.5 qts of oil in the system of a bbc HV pump to stop cavitation just on a non moving car Minus crankshaft windage. So everything you can do to get it back in the pan bottom is a plus. Plus i throw in a extra qt.
Rod bolts streatching L19 min. strength as for a rpm ing BBC you will see babbit bewteen your rod caps with anything less.
So is it your cross drilled crank or did you just learn something here that went unchecked and blame the crank because it was crossed drilled. Bet ya it was your main caps, and you didnt know it.

N/A and love spinning the bitch like a sbc and dont ask why]

[rally]

Still wouldnt use a cross drille crank.

[4sfed]

A little off topic . . . does anyone have any reference material on the evils of cross-drilled rod journals? I've found only one SAE paper (2004-01-1599) with some information. My customers are stuck with the choice of high quality OEM forged cranks (4 cylinder) with cross-drilled main and rod journals, or a $3500 billet. I've only been able to convince one to go the aftermarket route. If plugging the trailing side of the rod journal would improve bearing life, that would put me a step ahead of my competition.

[pamotorman]

Well this comment on YB says a lot I think :

As for the Chevy BB crankshaft cross drilled 5140 came out because of Nascar racing, i received afew back in the day and they were also made of 1053 cross drilled as well.
With the much better 4340 forging made aftermarket cross drill as well i have ran all of them. Including non cross drilled bbc cranks.
To many other problems have been assocated to running crossdrill cranks and blamed on cross drilling. Yes they are a breed that must use a diff. style of building but they all survive to 9500k and into the 10k area. Drag racing. I build my own engines and some of the problems others blame cross drilling to are

A= Low oil pressure due to not enough Volume of oil. No volume no pressure. Crossdrilled cranks requires more oil to keep up the pressure and a sump of 8 qts, or more. Be it centrifical force throw it off or main bearing cavitation not getting fed by enough oil. High volume oil pump required.
B= main cap walk, and or main cap hole getting distorted under load, caused by 80 pounds out of balance and the usual 5 and 10 gram balance job aint gonna cut it at 8000 plus rpms, trumendious amount of force on the mains.

C= No real race motor esp. BBC ever should use oem main caps period and 98% of people think of a damn good reason to say otherwise but 1" of iron main cap under the crank will only support maybe 7200 rpms at a modest HP level before they start bending downward and take out the main bearings and then rods Hence cap walk . Bolts in hell will stop this. You need a billet steel main cap with a 1.5 inch thick mian cap web at a min. of heat treated 1045 steel 4140 is super. That is needed to keep a 80 piund crank thats flexing and bending at any HP level. So dont blame it on a cross drilled crank when the rest of it isnt ready to do battle.

D = So many ideas have been tried in the past and what doesnt work is fully grooved bearings , half or none at the most. Yes you lose oil wedge. Grooving the crank lost out real fast as well.

E= Motor mounts including steel replacement esp. On a good hooking clutch car and auto chassis are almost right there today being connected to oem frame mounts will pull apart the block at mains 2 and 3 and cause suspected main cap walk, but really caused by block getting pulled apart breifly at the hit long enough to start the lose of them two main bearings and the process has been started. Real High hp cars use motor places which allows crankshaft to spin freely undistorted and live.

F = Oil control , keeping the oil in the bottom with the pick up covered at all times even under decel. Time. Takes 4.5 qts of oil in the system of a bbc HV pump to stop cavitation just on a non moving car Minus crankshaft windage. So everything you can do to get it back in the pan bottom is a plus. Plus i throw in a extra qt.
Rod bolts streatching L19 min. strength as for a rpm ing BBC you will see babbit bewteen your rod caps with anything less.
So is it your cross drilled crank or did you just learn something here that went unchecked and blame the crank because it was crossed drilled. Bet ya it was your main caps, and you didnt know it.

N/A and love spinning the bitch like a sbc and dont ask why]

cap walk is a big problem as you stated. the block register is only to locate the caps in the block so to prevent them from moving around because of the clearance around the cap bolts as they are pushed downward and pulled inward with the force of crank is dowel pins either hollow around the bolts or solid ones if enough room to install them.

[n5ifi]

My son purchased a crank, rods, pistons and bearings for one of his motors (I assembled) from a well known company in California and when it came in I noticed that it was a cross drilled crank.
It scared me so I talked to the owner of the company about it and told him about my concerns due to what I had read about cross drilled cranks on this site as well as other sites.
He told me, trust me it will be fine. I did and he was right. 408W Ford turns 7500 every pass and no problems at all. It's a bracket/Index motor that only makes about 650 HP but it runs strong and never has had any oil pressure issues at all. I was skeptical but the proof is that it's been working fine for several years now. I was trying to remember what I saw that was different about it from say a non cross drilled crank and if I remember right it had a full groove bearing (or 3/4 groove) on the thrust only. I may be wrong about that because it's been a few years ago that I built the motor. We run Brad Penn oil and methanol for fuel.

[Walter R. Malik]

This is just spitballing here, but maybe there is a reduction in friction in that area, and it doesn't need the surface area requirements to support the load in that section?
Maybe extending to increased cooling/flow as well? I know the flow should be limited by the smallest clearance, but I recall seeing something about "pulsations" if you will in certain oiling systems that could cause momentary cavitations in an oil feed, and having extra volume in certain areas could help with this.

I honestly have no idea, but I'd like to learn why, if such is the case.

As some SAE testing and evaluation has shown, 3/4 or full groove main bearings can only be advantageous to an oiling deficiency on the rod bearings.
It is actually less supportive to the main bearings and the SAE testing has shown that even LESS than a 180 degree groove in the main bearing will support the mains with a better hydrostatic layer of oil.

They could be wrong ... but, I doubt it.

Cavitations usually happen when the oil boils or aerates at on the INLET side of the pump causing the pulsations.

Ok, I'll bite.
What causes the rod bearing oiling deficiency you speak of in the first place?
You say "some SAE testing"? Does this mean there is differing opinions/results to this testing?
Are you saying these longer grooves show positive because they provide an increase in rod bearing oiling time?
Does this increase in groove length actually increase flow to the rod bearing, or just the time it is oiled?
What loads and rpms where these test you mention conducted at?
At a higher rpm, like a performance engine would run at, is the groove pressure consistent throughout the length of the groove?

Let's take 'em in order;
1. Lots of different criteria can contribute to create rod bearing oiling deficiencies.
2, Every SAE test conducted is NOT something to do with oiling.
3. I am not saying ... only repeating that it happens; read the SAE report.
4. BOTH
5. Again, get & read the SAE report; I am sure it is in there.
6. NO

[af2]

From the dead LOL.

http://www.speedtalk.com/forum/viewtopi ... 1&start=15

[naukkis79]

I know very little about BBC and them using cross drilled crankshaft.
What I do know is I have built thousands of 4 and 6 cyl Honda's, Mitsubisha's and Toyota's.
Most were turbo charged engines using factory cross drilled cranks.
These engines made 100 to 250 HP per cylinder turning RPM of up to 10,000.
These engines have no lower end problems.

They use cross-drilling in different meaning in jap and euro engines. In straight engines you could
drill straight hole from one main bearing to 2 rod journals, if drilled with more holes to get
individual support from one main to one rod journal it's called cross-drilled as drillings kind of crosses.

Usually low-performance engines come with non cross drilled cranks. But there ain't more than one
oil hole per journal, for performance engines there's usually 360 degree grooved mains.

In V8's they use cross-drilling with through drilled journals which ain't any good and which is newer
used in euro or jap engines.

[Kevin Johnson]

In V8's they use cross-drilling with through drilled journals which ain't any good and which is newer
used in euro or jap engines.

Jap Yamaha F350 V8 outboard marine crankshaft:

$_57 a.jpg

$_57 b.jpg

$_57 c.jpg

$_57 d.jpg

Looks like that same style crankshaft is used in the Volvo B8444S

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