High volume oil pump

[GrabberOrange69]

This high volume vs standard vs high pressure is funny. Is not the oil pressure on the gauge, say 60 psi the measure of restriction that the pump is pushing against, or rather the size of holes (bearing clearances, etc) in the engine oil passages that the pump is trying to push the oil through. The bearing clearances don't change if you switch pumps so if you use a standard, high pressure, or high volume pump, all at 60 psi, you have EXACTLY THE SAME AMOUNT OF OIL PASSING THROUGH THE ENGINE WITH ALL THREE PUMPS. The high pressure pump may potentially start at a higher pressure and will therefore push more oil through the engine than a high volume pump. The high volume pump may BYPASS more oil through the pump than the standard or high pressure pumps at the same pressure but will have a greater reserve capacity to maintain the amount of oil pressure as the clearances increase as the engine wears. The only time the oil volume THROUGH THE ENGINE changes is when you change the pressure or the clearances.

+1

There was an interesting article in the mid 1980s in Autoweek magazine (of all places) written buy a guy who continued to grenade engines in his prepped 4cyl road course car (I don't recall the make). The essentials were he had and maintained 10psi per 1000rpm all the way to his 7,500 rpm limit, but kept grenading motors - all had the rod journal furthest from the oil pump looking staved for oil. He checked everything - passages clean, oil pump working. He then bolted a HV pump to no avail. He installed a full dry sump system with 10qts of oil and lots of volume - bam...still blowing motors. Then he upped the pressure - alot -and stopped blowing the engine, but gave up too much HP to drive the external dry sump pump at stupid high pressures.

The light bulb finally went off that the oil pressure was only indicative of resistance to oil flow through the system - as measured close to the pump. He decided to drill into the oil passages to put a sender at each main bearing to measure pressure at each main - with the gauges in the cockpit . Bingo! As the motor increased in RPM, there came a point where pressure started dropping off at the mains furthest from the pump - HV pump wouldn't solve it, only an increase in pressure.

The final solution for him was to plum an external oil line from the pump directly to the furthest main. He then lowered the pressure back to reasonable levels, saving the HP to drive the high pressure pump while oiling the furthest main from the pump.

Food for thought...

 

[bm02tj]

I have a HV pump and added the optional windage tray other than the double pan gasket (dont tighten bolts to much )
my 400 bored .040 with closed chamber heads has seen some 5500 plus RPM

 

[IQ52]

This high volume vs standard vs high pressure is funny. Is not the oil pressure on the gauge, say 60 psi the measure of restriction that the pump is pushing against, or rather the size of holes (bearing clearances, etc) in the engine oil passages that the pump is trying to push the oil through. The bearing clearances don't change if you switch pumps so if you use a standard, high pressure, or high volume pump, all at 60 psi, you have EXACTLY THE SAME AMOUNT OF OIL PASSING THROUGH THE ENGINE WITH ALL THREE PUMPS. The high pressure pump may potentially start at a higher pressure and will therefore push more oil through the engine than a high volume pump. The high volume pump may BYPASS more oil through the pump than the standard or high pressure pumps at the same pressure but will have a greater reserve capacity to maintain the amount of oil pressure as the clearances increase as the engine wears. The only time the oil volume THROUGH THE ENGINE changes is when you change the pressure or the clearances.

Heck, I've run the 451 at 75 psi, with the factory 4 qt oil pan and a high volume pump to 7600 rpm and not lost oil pressure.

 

[68 Sport Satellite]

I'm building my 451 and bought the Melling HP pump. Whoops, I think I was confused. Today I've been reading other threads talking about both the HP and HV Melling units having performance issues, especially with newly built engines and some are recommending the Mopar OEM units instead. Maybe Melling used to make good pumps and now having issues? This is a street car, 6-qt hemi pan, windage tray, 1/2" pickup. What's my best bet here and whatever I get, do I need to upgrade the spring?

 

[bm02tj]

just use the HV pump with the stock spring