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Ballpark Engine Lubricant Oil Flow Rate

Ballpark Engine Lubricant Oil Flow Rate

Ballpark Engine Lubricant Oil Flow Rate

Can anyone give me a guesstimate of my lubricating oil flow rate to help me size an oil cooler and calculate plumbing system losses?

Engine is a VW A1 (Rabbit, Scirocco) 1600cc 4 cylinder, 5 main brg, solid lifters, bearing clearances slightly bigger than std (~.002"), running SAE 30 or 50 oil.  Runs 60+ psi at revs of 3500-7000 RPM, oil temp (after cooler addition!) say 250 Deg F.  

Nothing really unusual about engine having said all that, so the flow rate for any roughly similar engine will get me pointed in the right direction.

Thanks in advance!

Al Seim

Replies continue below

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RE: Ballpark Engine Lubricant Oil Flow Rate

The applications engineer for Setrab Heat Exchangers gave a high side estimate of 2 gph, which surprisingly (to me anyway) gave a pressure drop of only 1.5 psi across a smallish (10 row) cooler, so it looks as if pressure drop is not a problem for me in this application.


(I'm still interested if anybody has any flow numbers for any remotely similar engines)

Al Seim

RE: Ballpark Engine Lubricant Oil Flow Rate


...high side estimate of 2 gph,

2gph ?


RE: Ballpark Engine Lubricant Oil Flow Rate

Oops, sorry, 2 gpm.

Got me!


RE: Ballpark Engine Lubricant Oil Flow Rate

Since oil is incompressible (for our purposes), the flow rate will be determined by the swept volume of your oil pump, times it's RPM (some run at crank speed, some at cam speed).
You could calculate the swept volume by carefully measuring the oil pump components, but it's probably possible to just measure.
Place the oil pickup into a container. Add a measured quantity of oil. Rotate the pump a known number of times. Measure the oil remaining in the container.
This is easiest if the oil pump is a seperate piece that can be operated apart from the motor. If not, you'll have to get creative.


RE: Ballpark Engine Lubricant Oil Flow Rate

You can push some plasticine into the gap between the gear and the housing, pat it down, smooth it off, then remove the plasticine intact, then drop it into a measuring cylinder with some water in it and note the volume displaced by before and after readings of water level.

You can do this foe a number of gears until you get enough to give an accurate reading with the equipment you have

From there you can do the sums on how many times a tooth passes the discharge port in a given time at a given engine rpm.

pat   pprimmer@acay.com.au
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