[curtis73]

Originally Posted by ScoTFrenzel

4000 to 6000 rpm will NOT quadruple the pressure, nor the volume.
Oil pressure is controlled by a spring loaded pop off valve, which controls not only the pressure maximum but the overall volume pumped into the galleries.
Bypassing only reroutes the output to the input side of most of the pumps.

Actually it does on any of my builds. 20 psi at idle up to an 80 psi pop off... that's quadruple. Not quadruple the absolute pressure, but quadruple the pressure relative to atmospheric.

IMO most shafts fatigue and twist off do to harmonic pulsations, not "oil pressure" that somehow? spikes to a million pounds and twists it off.

You're right, harmonics play a very small role in pump fatigue, but I was intending to demonstrate how 15 hp drag is plausible at peak pressures. Racers don't upgrade to 7/16" drives because they're afraid of vibrations, they just have twisted small ones off too many times to risk it.

Dyno tests show that 60 amps draw on an alternator pulls 1 1/2 hp beyond the mechaincal load, which, I do not know how much power it takes to turn an alternator at 5000, do you?

No, but again, my point was to demonstrate that you can't judge something by its performance outside of the real operational parameters. Comparing an oil pump's drag by spinning it with a drill to being anything like operating parameters at redline and 60-70 psi is pretty pointless. Sure it only takes 1/8 hp to produce idle-like pressure in an otherwise empty block, but it takes a heck of a lot to produce 60 psi while spinning 6000 RPM.

[machine shop tom]

IIRC, the stock-volume BBC pump actually pumps less volume than a stock-volume SBC pump because the additonal teeth on the gears in the BBC pump teeth occupy more volume..........


tom

[barnym17]

The simple fix for the stock small block oiling system is DON'T FIX IT ,IT AIN"T BROKE!

[SSedan64]

Here's a few good pump Mods>
http://www.chevytech.com/2c63.html

By David Vizard
http://www.gofastnews.com/board/tech...ower-mods.html

[machine shop tom]

Originally Posted by barnym17

The simple fix for the stock small block oiling system is DON'T FIX IT ,IT AIN"T BROKE!

Bingo.

tom

[CNC BLOCKS NE]

We have seen engines come in the shop with BBC pumps and have seen the rear main cracked from I would say the extra weight of the BBC pump and being a 400 cap is weaker then a 350 cap because of the housing bore size it may not be a good idea to run that pump.

We have seen that the Milidon pick up fit to tight it the pump cover causing distortion in so beware.

[Schurkey]

Originally Posted by curtis73

No, but since the drag on the pump is exponential, (a function of the square of the speed and the pressure based on viscosity) and the pump spins the same speed as the engine (double the cam speed), try spinning that pump to 6000 with some cold 10w40 in the case. Now you've quadrupled the pressure, which (other factors excluded) has multiplied the drag on the pump by at least a factor of 16 - and that is simply from the oil pressure. That doesn't take into consideration the exponential increases in friction on the driveshaft, the drive gear on the cam, and the gerotor friction inside the pump.

What gear mechanism causes the oil pump to spin at crankshaft speed?

Oil pump runs at DISTRIBUTOR speed, which is same as camshaft speed, because the cam/distributor gear ratio is 1:1, which is 1/2 the crankshaft speed due to timing gear ratio.

SBC and BBC do not use a gerotor design except perhaps as specialized aftermarket equipment, but you're correct that higher RPM would cause additional friction even with spur gears.

Originally Posted by Guy Hiltz

as to DoubleVision's statement that a high volume oil pump takes 12 or mor hp to drive,I would have to see a back to back dyno test beforeI would believe it.
Guy

First Guess: The cam/distributor gear cannot transmit 12 horsepower.

Second Guess: Cam/distributor gear would have problems transmitting 2 horsepower with any reasonable life-span.

Originally Posted by machine shop tom

IIRC, the stock-volume BBC pump actually pumps less volume than a stock-volume SBC pump because the additonal teeth on the gears in the BBC pump teeth occupy more volume..........

Taller gears. Larger diameter, too, I think.

[327NUT]

Schurkey, this thread is 3.5 yrs old.