oil pump

a rebuilt engine with a stock pan and under 6000 rpm go stock volume pump. the hi volume pump has rotors that are 25% longer, and if clearances are larger than stock, like what we do for rods and mains in a race engine,can suck up and pump out more oil, and as rpms go up for any length of time, a 4 quart pan can get sucked dry. I have been there