First some history, and then a little tech.

I've just replaced the spring in my oil pump.

I had a high volume pump which gave me about 35 PSI of oil pressure
at ~900 RPM and 60 PSI by 3500 RPM.

Once the pressure hit 60 PSI on the gauge at 3500 RPM, "SOMETHING"
limited the pressure to 60 PSI as the RPM of the motor raised from
3500 to 6000 RPM.


The new spring (Black) allows for 60 PSI cold up to about 5500 RPM and 20 PSI at 900 RPM.

Once the engine is warm, the pressure "LIMITS" to 40 PSI at
3500 RPM. As the motor raises above 3500 RPM, the pressure
drops to about 30 PSI and climbs back to 40 PSI...it never exceeds
40 PSI.

My questions are:

1. How much oil pressure is adequate for 6000 RPM? This is a street/strip
motor. I use 10W30 motor oil.

I've always been told that 10 PSI per 1000 RPM is the rule.

2. Should I return to the high pressure spring that limits 60 PSI
from 3500 RPM upward to 6000 RPM?

3. What is regulating the pressure? Is it the valve in the oil pump,
or the adapter at the oil filter?

4. Lastly, if I use the high pressure oil spring, is any oil getting
bypassed around the filter once the pressure is limited to 60 PSI,
or does it flow back into the oil pan? What and when does the
spring open in the device located at the oil filter adapter?

I've tried researching the oil circuit and protection devices, but
I'm coming up with vague information.

Tomorrow I'd like to drop the oil pan to fix a leak and adjust the oil
pump pressure while I'm in the process.

Some pros and cons for high volume pumps, as well as oil circuit protection
devices would be awesome!

 

Just so you don't think I took the easy way out, here are my
findings:

1. I was told 10 PSI per 1000 RPM

2. Not sure, what is the difference?

3. I believe the valve in the oil pump is regulating the pressure.

4. The relief valve in the oil filter adapter only opens once there
is a block in flow. The pressure differential between the spring
in the adapter and the oil circuit must be at least (xxx PSI) before
the bypass circuit is active.

I am guessing this bypass circuit opens once the pressure differential
reaches about 35 PSI (60 PSI of filter flow plus 35 PSI of pressure "back up").

 

10 psi per 1000 rpm is normal but also excessive. A pump trying to produce 60 psi at 6000 rpm is using up a lot of HP doing it. A maximum of 40 psi is all that's required and 10 psi at idle is fine.

Pressure is just an indication of how tight or loose the internal parts are. The key is to have volume. You want the pump to push as much oil through the system as possible to keep everything lubricated. If pressure is too high then there's restriction somewhere. Too low and oil is flowing out somewhere too quickly. Think of a garden hose. A half inch hose free flowing could probably fill a bucket in about a minute but there's little pressure. Cover part of the opening with your finger and you increase the pressure but it should still fill the bucket in roughly the same time.

The old trick for pumping more oil is to use a BBC pump on a SBC. They're interchangable but the BBC pump pushes more oil. A SBC pump has 4 bolts on the pump cover. The BBC pump has 5.

 

I thought thats what most "high volume" pumps were. Basically just big block pumps with screens to fit small block pans? (in reference to the basic Melling or Speed Pro pumps)

Becuase, before the M55-HV, wasn't the M77 what was used?

 

Personally I would go to a regular volume pump with a high pressure spring. The GM white spring is a good one to use.

 

Good article on oil pumps.

http://www.stockcarracing.com/techar...134_0309_pump/

Should answer many of your questions.

-Mindgame

 

Nice! What a great article.

Thanks for all of the replies everyone. My assumptions have been
confirmed - and then some!

You don't realize the impact on the ignition even though the distributor
is driven from the same point.

Cool stuff!

Now I just have to get my head around watching the oil gauge
sit at 30 PSI @ 6000 RPM.

It will be a big psychological hurdle to over come. I'm sure the
paranoia will set in for a while

 

That's easy. I don't even watch mine. Right beside it I have a 2" round red clearance light mounted in the dash. I would have used a 4" round tail light but there wasn't enough room to mount it. It's connected to another sensor on the block. When oil pressure gets below 5 psi, the big red light comes on. That's the only time I worry.

One race I crossed the finish line and the light was flickering. I quickly glanced at the gauge and it said I still had good pressure. I came back up the return road and the light was still flickering but pressure was good. I use a mechanical gauge. When I got back to the pits I found the wire at the sending unit for the light fell off. It provides a ground and was brushing up against the header creating a ground and making the light flicker.

I use both the pressure gauge and warning light but rely more on the light. It's hard to watch gauges while going down the track but when a big red light comes on, you can't miss it.

I just finished reading that article. Just about mentions everything I said in my above post

Another trick to do is to use a larger capacity oil pan but don't use the extra oil. The engine only needs to have enough oil to keep everything lubricated so only a minimum of oil is needed in the pan. I use a 7 quart pan on my BBC but keep it at the ADD level. This still allows plenty of oil to cover the pickup plus it keeps the oil below the crank and windage tray. The baffels in the pan keep the oil in the sump during hard launches and decelleration. There are even some racers that only keep 3 quarts in the pan.

The block can also be modified for better oil control. SBC require the drain holes in the lifter valley to be plugged which will force the oil to return to the front of the block and drain into the timing chain area. This keeps the oil from draining down onto the crank causing windage.

 

I meant that quote more to mean, I'm accustomed to seeing
50 PSI @ 6000, not 30 PSI.

I don't want it to freak me out once I glance down and see the
new reading.

That's a good idea about the warning lamp. I guess it wouldn't
take much to screw in an electric sender and wire up a light.

As for my only unanswered question: When/How does the relief
valve in the oil filter adapter come into play?

How much pressure is required to open that valve? 100 PSI? 5 PSI?

Does it partially open under high pressure oil pump action?

What if the filter was totally plugged, how sensistive is that bypass
valve to allow unfiltered oil to the engine?

Are you picking up what I'm putting down?

 

From a GM service manual

"Oil enters the pump through a screened inlet located near the bottom rear of the oil pan. The pressurized oil from the pump passes through the oil filter. The oil filter base has a by-pass valve which, in the event of filter restriction, will open at 5.5 to 6.5 psi."

Oil flowing through the filter although it's pressurized, it's unrestricted. The by-pass valve is actually looking for backpressure. If the outlet pressure is less than the inlet pressure then there must be a restriction in the filter and the by-pass opens. It's just a simple valve with equal oil pressure on both sides. When the outlet side pressure drops, the valve opens. Newer vehicles with a factory oil cooler have a similar system but it's set at around 12 PSI difference. If the cooler plugs and the pressure drops more than 12 psi, the oil is by-passed around the cooler.

Something like the brake pressure differential valve. When brake pressure is the same on both sides there's no fault. Lose pressure on one side and the valve moves over, completes a curcuit and turns on the brake warning light.

 

Generally,and I mean generally,40PSI will be good enough out the back door.It has to have the volume to produce the pressire.
10psi per thousand RPM's is not needed except on a loose clearanced,8000+RPM,trailer queen or a BB F***If you have a street/strip engine 40psi@ 6000RPM's hot should be plenty.The pump spring is doing all the regulating.

 

Nice answers guys. That puts a wrap on my 'black box' understanding
of the oil system.

I'm actually impressed that I picked off most of the operating
principals in my second post.

It's so difficult to find good information these days. It's amazing
how many different versions of concept you'll hear by talking to
a handful of people. The sad part is, most of them picked it up
from daddy, or Mr. Dumb's Internet site and take it to the bank.

Thanks for all of your time everyone!

 

And then some.



System One has a pretty nice, and easily adjustable, oil pump on the market. Not that it's too tough a chore but the price is a little steep.

-Mindgame

 

I'd prefer it to state push as much oil through the system as NECESSARY. Pushing as much as possible, is too much/overkill. Sounds like to old adage, more is better. In due respect, I find your post contradictory.

I read the article through. I find it misleading and contradictory as well. If you can generate pressure, you have adequate volume for the circuit/passages/clearances needing lubing. As noted above, the circuit in question, will determine the pressure generated.

Although I subscribe to these very techniques myself, in fairness, a warning could be attached to these paragraphs to prevent some unwary individual from copying these techniques on their stocker. Depending on pump in use, a qt. low, could be fatal. Even though roller lifters are used, for high mileage expectations, it should be noted, there is no direct lifter/cam lobe lubrication, so this area depends on oil 'splash' for lube. Some of this splash comes from center access holes in block.

The testing I've done, concludes something more like 8.0-8.5#, so, I consider the manual.... ah, close. More in line with what I've read elsewhere.

The LT systems I've come across, use the same identical valve/spring assembly in the oil filter differential bypass valve as what is in the cooler adapter. Not able to speak for all LTx vehicles, but would believe they are the same.

I prefer to describe it as a pressure differential bypass valve myself.


I agree with this guy, especially about the "It has to.... pressure".

 

Alot of stuff there, which part(s) do you find "contradictory" or "misleading" arnie?

That article was obviously a product of interviews with the two engineers from Melling, Mike Osterhaus and Cal Rydjord. So maybe they are "misleading" on purpose or are they unaware of such deeds?



-Mindgame