Don Terrill’s Speed-Talk

Looking for OE Std. volume oil pump GPM ratings for both a sbc and sbm from the same testing source.

Did a search that came up with a lot of info, but not that specifically.

Thanks

517-787-8172, Ext. 2506 for Melling Tech line. I would think that they have graphs for flow through a calibrated orifice for the SBC and LA.

Kevin Johnson wrote: ↑Mon May 11, 2020 3:49 pm 517-787-8172, Ext. 2506 for Melling Tech line. I would think that they have graphs for flow through a calibrated orifice for the SBC and LA.

Left them a message, thank you : )

Well, I got an answer, but Melling tested the sbc M-55 pump at 508 rpm, and the sbm M-72 pump at 310 rpm : /

Would it be a linear calculation if I adjust the M-72 to 508 rpm?

Physically calculate the cubic inch displacement of the pumps to determine gpm

IIRC at a "set" RPM a spur gear( GM) pump has less output volume than a gerotor( Mopar/Ford) style pump simply by design.

scoob314 wrote: ↑Tue May 12, 2020 11:57 am Physically calculate the cubic inch displacement of the pumps to determine gpm

The only correct answer there is.. From the displacement of the pump fairly simple to determine the flow rate. There are a bunch of hydraulic online calculators that will give you gallon per minute from displ and rpm. All melling needs to know is the displ of the pump which they should definately know and give you that. If you can measure the gears and cross section of the pump you can input that into any calculator.

In one of the older small block chry;ser books they had a graph of oil pump output, but I don’t know if it was graduated with actual GPM or GPH but if you have the test RPM from Melling and that graph you may be able to get what you want.

I’d post a picture of the graph, but I’m not at home and don’t have the book with me.

I’m also running what is considered tighter than normal oil clearance and I’ve tubed the block and I have way too much oil volume. I used a HV pump when I probably could have used a standard pump, or maybe even have been able to shorten the gears a bit from standard volume.

Since liquid is incompressible, with no outlet restriction to create internal leakage-inducing pressure I don't see why you couldn't just submerge the pump inlet in light oil, spin it with a speeder handle to purge any air and then measure the delivered volume for say 10 revolutions. Calculate volume per rev. and convert to GPM at any RPM, remembering that a distributor-driven pump pump turns at half engine speed.
Note: until/unless the bypass opens, flow will be virtually linear with RPM.

I think a positive displacement pump, pumping liquid should be darn close to linear

I would go with a test supplied by the manufacturer.

Pump internal bleed, rotor/gear to body clearance, and end plate clearances diminish calculated output volumes.

Cheers.

Generally calculate in 87% efficiency

Contact Verne Schumann @ Schumann Oil Pumps. 804.779.0888 or schumannoilpumps.com. He has done exhaustive testing of OEM oil pumps and offers many variations of oil pumps; i.e. high volume, OE standard volume, lower than standard OE volume, high pressure, low pressure, etc., etc.

In order to calculate the "net" volume of an oil pump, there are many related factors that must be included in the analysis. A few of these factors are pump type (gear or gerotor); pickup size and shape (i.e. radius of bends in the pickup tube, shape and dimensions of pickup screen); type of relief valve utilized; dimension and shape of oil pump outlet/engine oil inlet, etc., etc.
"Net" oil flow is all that really matters, but remember that higher volume and/or pressure will increase friction and use horsepower . . . . . . .