ZCP M3

Hello all,
I've been trying to find some solid numbers for the flow rating of the stock oil pump and have come up with some interesting results that need clarifying. Reason I am asking is so i can get a properly sized pressure section in my dry sump pump.

1) The manual has been quoted as stating the pump is rated for 56LPM @6000 RPM. Is that pump RPM or engine RPM?

2) What is the speed of the pump in relation to the crankshaft? I've seen 34/21 and 21/34. I find it hard to believe that pump is turning at 14,000RPM when the engine is at redline.

3) What is the oil pressure that needs to be maintained during VTEC and under WOT enviroments?

Thanks,
-Zach

SpitfireS

ZCP M3 Posted on Oct 15 2007, 09:25 PM
My manual says 58.4 liter @ 6000 (crank) rpm.
It doesn't specifically state crank rpm, but the waterpumps flow rate is also stated @ 6000 rpm.
99.9% sure its engine rpm.

Whatever the ratio is, the pump sprocket is the smaller one.


Its also oil type dependant (a little) IMO.
My manual specs 590 kPa @ 3000 rpm (with the old oil jet bolts).
I've seen Slows2k post the revs at which the oil pressure is at max but I don't recall the pressure or the revs. (and the pressure @ revs is oil type dependant as well)

ZCP M3

Thanks for the reply!

So based on my calculations, at 6000rpm crank, the oil pump is turning at 9714rpm. Dividing 58.4LPM/9714RPM, I get 6mL of oil per revolution.

The pump is turning at 34/21 the speed of the crank, so at 9,000rpm crank speed, the pump is turning at 14571rpm.

Assuming the pump is efficient at that rpm, it would be supplying oil at 92.8 liters per minute.

That just seems incredibly high. To quote the dry sump pump manufacturer, "96LPM is what a 600 cubic inch diesel pulling tractor requires to maintain 160psi of pressure."

modifry

Maybe an engine with a redline of 3500 rpm doesn't need as much flow as one with a 9000 rpm redline?

Or maybe activating a second set of cam lobes with oil pressure requires a higher capacity pump?

ZCP M3

I guess that has to be it. My assumption is that when that VTEC soleniod opens those passage ways up, it basically doubles the area the oil has to flow into. So, to maintain the required pressure over an instantly bigger volume, it has to flow an insane amount. RPMs should have nothing to do with it.

ZCP M3

Bump. I guess the last question i have is this. Is the oil pump efficient at 9000 crank rpm? Has anyone hooked up a flow meter to the motor while on a dyno?

INTJ

That is way scary: 9,700 rpm is strato stratospheric. This confuses me why Honda is soo lukewarm on synthetic. I would assume all sorts of issues at that speed, like cavitation, impeller damage, etc. That must be some outstanding engineering.

SpitfireS

modifry Posted on Oct 16 2007, 03:21 AM
Engaging VTEC doesn't require that much engine oil.
VTEC is engaged by 2 little pistons that slide over and lock 3 rocker arms together.
Only during engagement itself you need the extra oil, the pistons aren't that big in diameter and the stroke is not that much, the oil volume needed (once) won't be much IMO.
Once VTEC is engaged, oil flow is almost like it was.
Only the oil that leaks past those little pistons is the extra oil you need (for maintaining VTEC)

Ratio's don't lie and chains don't slip, so the oil pump IS running at the revs you mentioned if the ratio is what you mentioned.
From the drawings (they look like drawn photo-pictures.. btw) in my service manual and from the picture on SanLeandro Online Parts it looks like the sprocket on the oil pump shaft has only 18 teeth.
Te crankshaft sprocket has 34 teeth as far as I can tell.

If that is correct the oil pump is spinning even faster!

ZCP M3 Posted on Oct 16 2007, 04:11 PM
How fast would a fluid, 9 to 13 times thicker than water, be able to flow into the pump?
One more reason to use a xxW-30 oil.
Once the oil pumps bypass valve is open at higher revs (= higher pressure), some of the oil will flow directly back into the sump anyway.

IMO, getting a solid reading on oil flow one needs to hook up a flow meter inside the engine, between the oil pump and its outlet.
And then you miss the oil flowing back into the sump because of the opened bypass valve at higher revs.
In other words: its very hard to measure IMO.

INTJ Posted on Oct 16 2007, 07:30 PM
It's a Honda
Well.. in the PDF service manual (English version) they mention the engine oil pump being a Trochoid Pump and those pumps were designed and patented by Nippon Oil Pump company.
Google is our friend

ZCP M3

Interesting. So it isnt a linear correlation at higher rpms and the motor isn't recieving 96 liters per minute at 9000rpm. I have a feeling they list the flow rate at 6000rpm because it is the max flow the engine sees before the relief valve opens up. Looks like I'm ordering a pump that can supply 54 liters per minute at 85psi!