Cross Drilled Crank

[4sfed]

[quote="Kevin Johnson"]Jap Yamaha F350 V8 outboard marine crankshaft:

$_57 b.jpg

Is that a plug in the number 1 main?

[Kevin Johnson]

Is that a plug in the number 1 main?

Looks to me like a clean through cross-drill.

$_57 b.jpg

[Adger Smith]

Tell me that outboard engine doesn't spin high RPM with a cross drilled crank.. I think that is called a modified Y pattern if my eyes are working well this morning. Not sure what it is called over seas. That is similar to what GM put in the steel BB chevies.

I think this is just another one of those "Things" like rod ratio and flow theory that will be in constant discussion. That is all because of the engineering behind it is based on a complete system and application, not just the one part being discussed or looked at. There are some things that never have a"right or wrong" based on application.
BTW: I've freshened a few Super Class engines sold by R&M that had cross drilled cranks in them. Wonder why they did that when the "Book" says Cross drilled is so bad? Humm..Guess that could lead to a discussion about Business and Business practices.

[Kevin Johnson]

http://outboards.findthebest.com/l/166/Yamaha-F350 WOT is 6000 rpm.

You would have to have hands-on the B8444S crank to confirm it has the same cross-drilling pattern but I suspect it does.

http://en.wikipedia.org/wiki/Noble_M600 uses that block up to 7000 rpm.

[Adger Smith]

Kevin,
The Boat shop down the street brought one in to bore and clean. (a while back)
I'm saying that by memory & what I think I saw. I wasn't interested in detailed design when I looked at it, only doing the work required.

[Belgian1979]

Are always the same rod journals failing in crossdrilled cranks or is this not the case ? The reason I'm asking is, if the middle rod journals seem to fail, this is usually were the crank bends the most and could be that capwalk or something else is in play.

Furthermore, my own experience with a oil pressure drop and the mentioning of the problem occuring mainly at higher rpm, makes me also wonder if some other oil problem is involved as well.

[mustangcobra438]

From day 1 I have had issues with 3 and 7.
Best rod bearings ever did was with 3/4 groove bearings 7qts 20/50 vr1 .0025on rod and .0027 mains 60psi oil pressure which makes perfect sence to me.
When I switched to 7qts 10-30 syn vr1 after 30 passes 3/7 were wearing through my calico coated rod bearings. Car got faster after switching to 10/30 oil.
Next season went to a well know pump that bypasses oil external the pump instead to the pickup tube oil with 5qts same brand/wt oil, added a set of Keith craft Chevy style oil restrictors in back of block even though I have roller cam bearings that block off cam oil I wanted to slow it down to the rockers as well.
Engine made 5 passes faster than ever before and then 100ft out on the 6th I felt it drop a cylinder and shut it down immediately.
Best pass na on the 275 at 2900lbs was 5.62 with 1.25 60ft with 20% slippage on big end! (Didn't get new converter in time.)

What y'all thinking? Oiling issue from switching oil/wt/flow/ pressure? Or crank flex?

[Belgian1979]

From day 1 I have had issues with 3 and 7.
Best rod bearings ever did was with 3/4 groove bearings 7qts 20/50 vr1 .0025on rod and .0027 mains 60psi oil pressure which makes perfect sence to me.
When I switched to 7qts 10-30 syn vr1 after 30 passes 3/7 were wearing through my calico coated rod bearings. Car got faster after switching to 10/30 oil.
Next season went to a well know pump that bypasses oil external the pump instead to the pickup tube oil with 5qts same brand/wt oil, added a set of Keith craft Chevy style oil restrictors in back of block even though I have roller cam bearings that block off cam oil I wanted to slow it down to the rockers as well.
Engine made 5 passes faster than ever before and then 100ft out on the 6th I felt it drop a cylinder and shut it down immediately.
Best pass na on the 275 at 2900lbs was 5.62 with 1.25 60ft with 20% slippage on big end! (Didn't get new converter in time.)

What y'all thinking? Oiling issue from switching oil/wt/flow/ pressure? Or crank flex?

My thoughts :
An oil pump that bypasses externally would have to suck up the full flow that the pump can put out through the pickup tube. Not exactly sure if it can be done (have been thinking about doing something like that but finally went with less oil in the pan), but could be that your pump was heavily cavitating because of it. IT would be useful to know if on that last run your oil pressure was dropping at higher rpms.

Either that or you were having oil aeration.

[Kevin Johnson]

From day 1 I have had issues with 3 and 7.
Best rod bearings ever did was with 3/4 groove bearings 7qts 20/50 vr1 .0025on rod and .0027 mains 60psi oil pressure which makes perfect sence to me.
When I switched to 7qts 10-30 syn vr1 after 30 passes 3/7 were wearing through my calico coated rod bearings. Car got faster after switching to 10/30 oil.
Next season went to a well know pump that bypasses oil external the pump instead to the pickup tube oil with 5qts same brand/wt oil, added a set of Keith craft Chevy style oil restrictors in back of block even though I have roller cam bearings that block off cam oil I wanted to slow it down to the rockers as well.
Engine made 5 passes faster than ever before and then 100ft out on the 6th I felt it drop a cylinder and shut it down immediately.
Best pass na on the 275 at 2900lbs was 5.62 with 1.25 60ft with 20% slippage on big end! (Didn't get new converter in time.)

What y'all thinking? Oiling issue from switching oil/wt/flow/ pressure? Or crank flex?

I think that if you are going to be purchasing a new crank anyway it might be interesting to slice the old one apart and make sure there were not any defective or different drillings that could explain the 3/7 problem.

Aside: The Coventry Climax SAE paper has interesting notes on bypass oil pumps, the crank acting as a secondary pump and cross drilling during their development of Formula engines in the 1950s and 1960s.

[lorax]

My thoughts :
An oil pump that bypasses externally would have to suck up the full flow that the pump can put out through the pickup tube. Not exactly sure if it can be done (have been thinking about doing something like that but finally went with less oil in the pan), but could be that your pump was heavily cavitating because of it. IT would be useful to know if on that last run your oil pressure was dropping at higher rpms.

Either that or you were having oil aeration.

I ran a Systems 1 pump with an external dump for years/
The pickup and tube have to pass the same amount of oil when the relief is closed as a external dump. If its not large enough for flow of the pump, its not large enough.

[Kevin Johnson]

I ran a Systems 1 pump with an external dump for years/
The pickup and tube have to pass the same amount of oil when the relief is closed as a external dump. If its not large enough for flow of the pump, its not large enough.

You have to ensure that the decreased quiescent oil residence time in the pan (so less time for air release) with an external bypass (above pressure relief rpms) is countered by appropriate deaeration of the externally dumped oil. Either approach has issues that must be thought through.

[mustangcobra438]

From day 1 I have had issues with 3 and 7.
Best rod bearings ever did was with 3/4 groove bearings 7qts 20/50 vr1 .0025on rod and .0027 mains 60psi oil pressure which makes perfect sence to me.
When I switched to 7qts 10-30 syn vr1 after 30 passes 3/7 were wearing through my calico coated rod bearings. Car got faster after switching to 10/30 oil.
Next season went to a well know pump that bypasses oil external the pump instead to the pickup tube oil with 5qts same brand/wt oil, added a set of Keith craft Chevy style oil restrictors in back of block even though I have roller cam bearings that block off cam oil I wanted to slow it down to the rockers as well.
Engine made 5 passes faster than ever before and then 100ft out on the 6th I felt it drop a cylinder and shut it down immediately.
Best pass na on the 275 at 2900lbs was 5.62 with 1.25 60ft with 20% slippage on big end! (Didn't get new converter in time.)

What y'all thinking? Oiling issue from switching oil/wt/flow/ pressure? Or crank flex?

My thoughts :
An oil pump that bypasses externally would have to suck up the full flow that the pump can put out through the pickup tube. Not exactly sure if it can be done (have been thinking about doing something like that but finally went with less oil in the pan), but could be that your pump was heavily cavitating because of it. IT would be useful to know if on that last run your oil pressure was dropping at higher rpms.

Either that or you were having oil aeration.

I thought the whole purpose for the external bypass was to ensure that pump does not aerate or cavitate?
Can u explain the to me a little further.
I'm deff thinking about trashing this pump now.
Thanks

[Belgian1979]

It's all about how much oil the pump pums at a certain rpm. The volume increases with rpm. In a normal pump, the not used volume is recirculated to the inlet. Which makes that the pump only has to suck the difference through the inlet. If you bypass externally you have to suck all of the pumped volume through the inlet tube. You will experience a pressure drop, because the sizes of the pickup tubes is usually not very big vs the amount of oil that has to flow through it. If the pressure drop is big enough, you will pull the air out of the oil solution and get cavitation and that is detrimental imo.

I was contemplating dumping externally and used some calculators to see how much the pressure drop would be. I'm not saying it cannot be done, but it certainly will be borderline in the cases where there is already a good amount of air in the oil because of the rotating assembly.

Either system has advantages and disadvantages as was already said.

I reduced the volume of oil in the pan from what the manufacturer told me after I took off the pan and made tests. Turned out I needed about 1 1/2 quarts less in the pan in order to keep the oil level adequatly below the baffle + improved the baffling. Untill now (not enough high rpm running done yet) Idle pressures have been fine hot, so I assume it has worked for me. Still need to make a couple of high rpm passes when the FI is tuned right though for a final judgement. Looks good so far.

[mustangcobra438]

What is the best style pickup to use? Factory style or aftermarket rectangle boxes with mesh bottoms?
What kind if deflectors can be added to pickup and what works the best?
Anyone play around with this? Just brain storming.
Matt

[pamotorman]

What is the best style pickup to use? Factory style or aftermarket rectangle boxes with mesh bottoms?
What kind if deflectors can be added to pickup and what works the best?
Anyone play around with this? Just brain storming.
Matt

the factory one are make like they are because if the screen get plugged there is a hole in the center of the screen that will be sucked open to allow the oil to continue to flow. any pickup that does not cause a vortex to form will work