Do any engine buliders on here know what the GPM flow is required for BB mopars? After reading this article from Johnson oil pumps it has me interested. It seems alot of people waste power with really high flow and thick oils.

Flow rate depends on bearing clearances and how many other leaky areas are inside the engine. Tight clearances, roller cam bearings, bushed lifter bores, etc allow you to run with a lot less volume. Some guys work on this issue a lot and they are able to run low volume oil pumps. I'm not sure if anyone makes a low volume pump as a shelf item but they aren't too hard to build yourself. Just grind down a standard volume pump.

I'm going to have my motor built "tight" next freshining. I plan to run Amsoil's 5w20 racing oil.
I'm going to install a Johnson wet/vac oil pump. It's belt driven so I can adjust the pressure and volume.

How tight is tight in thousands, rod and main bearing and side clearences Looser might be better, let the oil flow

Not sure on the clearances, but I know thinner oil cools better and flows much faster.

What about RPM and stroke ?

How does that factor in?

A 4.5 stroke vs 3.75 stroke crank.

8200 RPM vs 6200 RPM

Bearing clearance is only part of the equation.

Spinning your oil pump on your engine stand is obviously taking less flow than running at WOT yet they still have roughly the same clearances.

I dont know the answer , just putting it out there.

I would like to know the answer too. I think Nascar teams have this down to a science. Of course not many are going to reveal anything.
Hell the spend millions just on oil research.
The only thing I know about their oils,is that it smells like rotten eggs, due to really high sulfer content.

It just depends if you're trying to get the last ounce of power out of the motor or not. You are only going to see about 2-3 hp difference between a HV pump and a low-volume pump. You are correct that some engine builders have worked this issue over the years and they just keep pushing the limit. The NHRA stock guys are probably the experts at cutting down on wasted energy since they have least amount to lose.

Roller cam bearings take less oil, Jesel rocker arms require less oil, bushed lifter bores help reduce volume a ton, etc. Do all of those tricks and go with tighter bearing clearances and then you might be able to run the 0-20 oils and a low volume pump.

Some guys use chillers in the pits to keep the engine cold and then an oil heater to warm the oil. They run zero weight oil and they leave the line with the water temp at less than 100 degrees. Unless you're chasing a world record there probably isn't any reason to go to all that work.

for 20+ years I've been a big advocate of using a ported stock pump...plenty of volume and pressure at higher RPM and a little less drag on the motor.

440Jim has done a great job documenting all the porting 'tricks' and I believe he still runs one on his 7200+ RPM 511 which I believe is essentially the same things I did on our Enginemasters 470 Pump. Do a search within the past couple months and you'll find great pics and step by step. I recently ported the #5 cap and all the internals similarly on my last small block and use the stock pump with a rear sump truck pan on my 341" Rocky.

Hot rodding is all about efficiency, the oiling system is a parasitic drag on the Cam and the distributor which puts more load on the crank through the timing chain. Using ahigh volume pump that uses the same internal "head" dimensions as a stock pump is kinda like building a stroker with stock heads.....With a HIGH performance application you typically are insuring the oil supply pressure and volume can keep up with the increased crank/valvetrain speed. Just like porting a head makes an engine more efficient at high RPM, I simply apply the same logic to the oil pump.

I always wondered what is the point of a 1/2" pump pick-up when the internals of the pump inlet and outlet passages themselves (including the HV) were barely 3/8"?

As the discharge pressure of the pump hits the crank there is a cumulative drop of pressure as oil "bleeds" through all the orifices of the Mains and rods as well as up the lifter galley....in essence that is "fixed" and predicable by the blueprinted specs of the system. Fluid dynamics (simple hydraulics) will dictate that any change to an upstream dischage orifice size will have a proportional effect on anything down the line. By making the pump more efficient you are effectively guaranteeing a more efficient pump flow to and discharge supply pressure and volume to the system.

Back 30 years ago Bracket motors ran heavy 40 and 50WT racing oils so bigger pumps were required just to feed the large clearances and bigger passages at the higher RPM, with modern oils (and typically lighter stronger components) this is seldom the case anymore.

According to this article http://johnsonsoilpumps.com/
The proper oil system can pick up 30+hp

just remember the oil system is also for removing heat. if it's race only that will be minimized with the shorter duty cycle.

Old engineering formula: total cross-sectional area of all leaks × 30 = pump volume.
Yes, it's linear: running .003" instead of .002" requires almost exactly 50% more oil volume.

Remember that the leak pressure from a working bearing at speed is many times higher than "gauge" pressure, can run into the high hundreds.

Lower pump volume is limited to 2 choices:
1. reduce the gear area
2. reduce the pump speed

For #1, the height of the gear stack is the easiest to do, as Andy said - just shorten the gears, shafts and body and put the cover back the same way. Extra plus: your bypass valve is now more efficient (= bigger proportion of volume).
Why not just use a low pressure spring?
Because every single molecule of oil still goes through the gears.

For #2, (obviously) an external pump can just change the pulley sizes to slow the pump down as much as you want. For people with money and using a crank trigger, you could replace the cam and pump gears with a shallower pitch and run it at any ratio you want since it's not timed (unlike the ignition).

the oil system is also for removing heat

True, and should be considered for any longer race than 30 seconds.
Since the volume passed through the cooler (if any) is reduced, the cooler rejects less heat.
The cure is to keep the oil in the cooler longer (more passes), and/or expose more cooler area to the airstream (ducting).

Very long post on this at SpeedTalk.
What actually provides pressure at the bearing is viscosity × local speed differential × the distance to the closest leak (which is why grooved bearings reduce oil pressure). The pump pressure is needed to refresh whatever is leaked away, but very little to do with the bearing support itself. If it were practical, you could pump acetone through at 2,000 psi and be safe (except for the film's load capacity).
The "10 psi per 1K RPM" is simply a good guess at the total leak rate of common engines - if the pump supplies this, the pressure continues to rise with RPM (never mind what the gauge says) unless the pump can't keep up with the leak, then you drive over the crank.
So, RPM is a factor?
Only with the main bearings.
???
The mains are stationary, the journals rotate at 100% engine speed (duh), but how fast does the rod journal rotate?
Trick question, the relative speed of the rod journal and bearing is lower, and stops and reverses during the crank stroke. The rod is only fully rotated vs. the block, not to its journal.
Then, how does it work?
Damned if I know, because dipper rods (= almost no delivery pressure) worked very well for 50 years as long as the bearings were big enough. The short oscillation period before reversal is evidently enough as long as it gets oil.
Example: pre-1953 Chevy L6 rod bearing is 2.311" ID and about 1.024" wide, gets about 20 hp each and 4,000 RPM in service and does fine.

X2, This is my setup with a 4.25 arm, 10w-30 @ 8700 every pass. never had a problem.

Don't know how he came up with these recommendations, but Joe Gibbs uses bearing clearances and operating temp as a means of selecting the correct engine oil viscosity in racing applications.

For example:

SAW 0W-20 = .0020 Clearance; moderate temperature applications (130F to 220F)

SAE 5W-20 = .0025 Clearance; best in engines operating with oil temperatures between (180F to 240F)

SAE 10W-30 = .0027 Clearance; best in engines operating with oil temperatures between (200F to 280F)

SAE 10W-40 = .0030 Clearance; No temp recommendation

SAE 15W-50 = No Clearance Recommendation; High temperature applications over 280 degrees (F)