Building a GMC 702 V-12

OK, Here is a problem the I was keyed into by Bob at Thunder V-12. The stock oil pump drops pressure around 3500 rpm. Now you can get a trick dry-sump set-up for a good bit of cash and work the plumbing issues OR here is the mod you will need to craft. I spent 6 months talking to the external dry sump manufacturers and also Titan who makes "beefed up" gerotor pumps for the nitro drag race crowd. The gerotor oil pump design has been around for a long time. Make a long story very short here, the 702 has the biggest gerotor of them all. It measures 1.37 inches in height compared to 1.10 inches that are run in nitro funny cars. So what gives? Cavitation! The suspended volitales and gases will cause a destructive cavitation issue under vacuum. Once your pumping cavity flashes with a vapor it looses the pressure on the compressing chamber (they are not actually chambers but "messhing" of the rotor and ring) and you have no oil going out to lubricate the motor. The design of the GMC gerotor used in these motors (both the V6 and V12) have just one surface of the gerotor fed. In this case it is the top and the bottom is left to take its fill from what is sucked from the top entry point. The owner of Titan Speed was very helpful in diagnosing the problem. I derived a modification to the standard pump to dual-feed it. As a note here the V6 gerotor is a 1.1 and the V12 is 1.37. Make sure you get a 1.37 if replacing the pump.