std vs high volume oil pump controversy

[DOTracer]

This seems to be quite a controversial topic. I've read opinions on both sides and still don't know what to believe. I've read some tech articles on Mellings site as well as the opinions of several machinists & engine builders.

Here's the basic combination (drag race).

high compression bbc (estimating approx 650-675 hp), solid roller cam with Crower Severe Duty lifters with the HIPPO option, 7000 rpm max, assuming pretty typical bearing clearances in the .0025 to .0003 range rod & main, steel rods, GZM belt driven vacuum pump set at 12" max.

My machinist prefers the Melling M77HV high volume pump and it appears as though Melling does recommend the HV in host high performance applications (they claim no real negatives of HV). EDIT: just spoke with a Melling tech rep and he recommended a "#10777 special HV pump along with their thread on #12701 pickup)"

I know Mike Lewis who posts here prefers the M77 standard volume pump with the high pressure spring installed. The oil pan I run is a B&B steel drag pan with a 7 quart capacity (internal screen & scraper along with the typical baffles & trap doors in the sump). The tech at B&B claims they prefer the same standard volume as Mike does...This tech even spoke of pumping the pan dry with HV which is also a controversial statement in itself.

OK, I respect the opinions of the board members here and would really like your input on this subject. Maybe we can get a good discussion going on here and dispell some myths on oiling systems and when to and when not to use a HV oil pump.

I'm gonna have both pumps here as well as the needed matching pickup to go along with that pump combination. I just need to decide which is really best suited to my combination.

Two variables in my combination are the added oiling holes in the Crower lifters and also the way the vacuum pump alters the oiling process inside the engine (helping pull oil through the system). Does these two factors change my oil pump selection?

thanks for any input
Todd

[Rick360]

I have a 360ci (4.06x3.48 ) 18* sbc with a full depth pan with a kickout. It has a stock oil pump and a moroso vacuum pump. The engine dyno'd 750hp @ 8000rpm carrying 15"Hg crankcase vacuum. It showed 49-50psi oil press thru 8500. Had no problems with the bearings etc running 2 years this way.

This engine had a roller cam so it had oil restrictors. This reduces the oil required for the top end so more is available to the crank/rods.

If the oil is at the bypass pressure of the pump, having more volume will not help anything. It won't pump more oil anywhere except thru the bypass port in the pump, heating and aerating the oil more.

Use a stock pump put a spring in it to provide the needed or wanted pressure.

Rick

[DOTracer]

I am not going to use top end restrictors. I had a bad experience in the past and refuse to use them anymore, plus this engine will see some minor street use, so I'd rather have oil up top tp cool the springs.

Knowing that, would that change your recommendation away from the standard volume pump to a HV pump?

BTW, thanks for taking time to reply.

[bill jones]

-I quit using hi-volume pumps in the late 1960's on Chev and Ford engines.
-It is my belief that they pump way too much oil up to the top and drainages back thru the block are never adequate enough.
-The Fords twist off the shafts, shear the roll pins and Chevy chew up the distributor gears.
-I have run stock SBC wetsump pumps on winged sprint cars on asphalt tracks where G-force is a big deal, with 4 quart sumps and NEVER had a bearing problem as long as we ran a straight 30W valvoline racing oil.
-Frank Parks ran his dragster in the late 70's with 30# oil pressure and 10,000 rpm and that engine had a stock oil pump and I have run lesser quality oval track engines with 30# for a full season with no oil related problems.
--------------------------------------------------
-The only details that I feel are extremely crucial is:
1-that you have an oil pressure warning light set up to about 5# less than what you see when the engine is hot and at 4000rpm.
2-that the drainage paths back to the pan be seriously enlarged on SBCs and on the Fords.
3-no heavy or thick oils.
4-I always enlarge the internal bypass channels inside the pumps or inside the pump covers to whatever is fairly easy to do.
5-I do NOT like the pickup tube any closer than about 1/2" from the pan floor and since I fabricate my own pickup tubes I always incorporate a mechanical stop so the pickup tube can't suck to the floor at high flow rates (high rpm).
---------------------------------------
-I am from the era when we never had vacuum pumps and none of us ever used any synthetic oils so we did it the only way we knew and it worked for us.
-The idiot light is the big story teller and will let you know when you have a problem.
-But I would prefer to have 50 to 65# on a SBC and I would never purposely set up an engine to have more than 75# (hot) for any reason that I can think of at the moment (other than maybe a blown BBC with aluminum rods and sloppy loose clearances but I don't build those types of engines).

[Guest]

Bill if you don,t mind telling us what do you enlarge the by pass chanel to and i would like to know if any body has ever used a pump that returns the oil to the pan instead off the gears like the callies oil pump.





mike

[Walline]

I agree with with Bill

It is my belief that they pump way too much oil up to the top and drainages back thru the block are never adequate enough. and Chevy chew up the distributor gears.

I have built many SBC always Drag race, with stock oil pumps. Last 406 turned 7600RPM and used a stock pump. No oiling issues. Just my two cents!

[panic]

IIRC Bill Jenkins commented that directing blow-off pressure back to the inlet (suction) gear set can cause chatter and cavitation if the relief valve shuttles open and closed too rapidly.
The purpose of excess volume into the feed side is that the volume going into the motor is the same (duh), but the volume going into the pan is reduced.

[bill jones]

-If you look at a stock SBC pump cover there is a small plug that looks like a freeze plug that I think is 5/16".
-That is the passage diameter that ultimately restricts the bypassing oil.
-I remove it and ream that hole to .390" or so and then I thread the plug hole 7-16"-20 and install a loctited allen screw.
-I also get in there with a small carbide ball burr and detail the corners of the intersection so oil can flow easier.
-The bypass piston & spring hole is 3/8" if I remember right so this makes it so that when the oil is cold you don't see quite as much oil pressure on a cold engine.
------------------------------------
-One other small detail is I flat sand the pump housing until I have .0020" to .0015" endplay on the gears, and I sand away the machine marks on the mounting surfaces of the pump and I remove the main cap dowels temporarily and also flat sand away those machine marks, so that the oil doesn't squirt out thru the parting surfaces.
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-If you haven't ever seen the leakage that occurs there maybe you need to drop a pan a little ways and prime the engine and watch all the oil that squirts out of those two places on stock pumps.
-------------------------------------
-I have never done the oil return back to the pan but I'll pull Ryan Brown's chain here and see if he will comment on that as I know he has done or still does do that.
----------------------------------------
-I think these modifications are like anything else, it all depends on how serious you are about taking care of your own problems.
-The idiot light is the single best thing I ever did and it took me destruction of two of my own personal engines when I was young before I got smart enough to understand the importance of what those lights teach you.

[Trev]

My experience with HV oil pumps is bad
On our Holden V8 the oil pump is driven of the cam by a gear and shaft to the oil pump
When using hi volume pumps they put extra pressure on the cam and chew the cam gear out in 50000 kms
I go with a blue printed standard pump

[Wolfplace]

This seems to be quite a controversial topic. I've read opinions on both sides and still don't know what to believe. I've read some tech articles on Mellings site as well as the opinions of several machinists & engine builders.

Here's the basic combination (drag race).

high compression bbc (estimating approx 650-675 hp), solid roller cam with Crower Severe Duty lifters with the HIPPO option, 7000 rpm max, assuming pretty typical bearing clearances in the .0025 to .0003 range rod & main, steel rods, GZM belt driven vacuum pump set at 12" max.

My machinist prefers the Melling M77HV high volume pump and it appears as though Melling does recommend the HV in host high performance applications (they claim no real negatives of HV). EDIT: just spoke with a Melling tech rep and he recommended a "#10777 special HV pump along with their thread on #12701 pickup)"

I know Mike Lewis who posts here prefers the M77 standard volume pump with the high pressure spring installed. The oil pan I run is a B&B steel drag pan with a 7 quart capacity (internal screen & scraper along with the typical baffles & trap doors in the sump). The tech at B&B claims they prefer the same standard volume as Mike does...This tech even spoke of pumping the pan dry with HV which is also a controversial statement in itself.

OK, I respect the opinions of the board members here and would really like your input on this subject. Maybe we can get a good discussion going on here and dispell some myths on oiling systems and when to and when not to use a HV oil pump.

I'm gonna have both pumps here as well as the needed matching pickup to go along with that pump combination. I just need to decide which is really best suited to my combination.

Two variables in my combination are the added oiling holes in the Crower lifters and also the way the vacuum pump alters the oiling process inside the engine (helping pull oil through the system). Does these two factors change my oil pump selection?

thanks for any input
Todd

Hi Bill,
Excellent post ,, couldnt' agree more,,,

Hey Todd,
No controversary here, you know my thoughts on Hi vol pumps
I have stated them before but here they are again just for giggles,,,


Hi Vol oil pumps,,,This is stuff I have posted this before but here it is again.

In my opinion, there is just no reason to run a hi volume pump in a BB Chevrolet.
It is unnecessary for almost any application.
You will be on the bypass about 80% of the time which does nothing but waste power, heat the oil & is harder on the distributor & cam gear.
A stock BB pump is probably one of the best designed factory wet sump pumps ever made.
The only reason I can think of to run a hi volume pump is if your engine builder insists on running bearing clearances you can drive a truck through.
The pressure & volume of oil going through your engine are not dictated by the pump, they are directly related to the clearance you run.

Will it "pump the pan dry? Absolutely not. This is not possible as the extra oil it pumps is dumped into the bypass & returned to the inlet side of the pump unless the pump has been modified to return it to the pan which I feel should have been done in the first place.

Will it accelerate drive gear wear?
Probably, especially if you are running excessive pressure.

Will it put more oil through the bearings?
Only if you have too much clearance.
It will put slightly more oil through the bearings but only because of added pressure not volume.
You can do the same thing with a hi pressure std vol pump.

Can it cause a drop in pressure at high rpm?
Yes if the pickup is too close to the pan you can suck a hole in the oil & it can cavitate.
Also there are some including me that believe the return circuit can cause cavitation under certain circumstances at high rpm.
Reasoning,, you are dumping hi pressure oil into the inlet which is a low pressure area & my feeling is you can actually cause a cavitation issue by "blowing" too much hi pressure oil into this circuit.
I could be way off here but have seen pressure drops of 5-10 lbs at high rpm on the dyno for no apparent reason & know the pickup was not the problem & windage shouldn't have been so I feel something was aerating the oil???
Bypassing to the pan cured the problem.

I do like to use a hi vol pump in a small block if you are using EDM lifters & doing much lower speed driving but you still don't want more than 60-70 lbs max.
This mostly applies to small blocks.

I have never used a hi vol pump on a rat including a 482 I used to run years ago that was shifted at about 8500.
I ran the stock L88 pump which did have slightly longer gears than the stock rat pump & had zero bearing problems.

[DOTracer]

One other small detail is I flat sand the pump housing until I have .0020" to .0015" endplay on the gears, and I sand away the machine marks on the mounting surfaces of the pump and I remove the main cap dowels temporarily and also flat sand away those machine marks, so that the oil doesn't squirt out thru the parting surfaces.

Quick question Bill...

How do you remove the dowel pins in the cap without destroying them? Or do you have a source for new replacement pins if the pin is damages upon removal?

[DOTracer]

I'm leaning towards using the Melling M77 standard volume pump with the high pressure spring. In the past, I've deburred & contoured the oil hole in the main cap which I'll likely do again. I'll also set the gear end play at .0015 to .0002 and try to sand the cap & pump mounting surfaces flat if I can figure out how to remove the dowel pins without ruining them. Will set the pickup at approx. 1/2" off the pan floor. I'll look at the pickup once installed and clearance set and possibly make a second brace to fight vibration.

[Wolfplace]

One other small detail is I flat sand the pump housing until I have .0020" to .0015" endplay on the gears, and I sand away the machine marks on the mounting surfaces of the pump and I remove the main cap dowels temporarily and also flat sand away those machine marks, so that the oil doesn't squirt out thru the parting surfaces.

Quick question Bill...

How do you remove the dowel pins in the cap without destroying them? Or do you have a source for new replacement pins if the pin is damages upon removal?

=
Hi Todd,
I use a collet type puller for them, same thing as is used for flywheel pins.
You can buy new pins from Pioneer if you need them. 1/4"

If you pickup doesn't have one add a brace on the bottom so it can't get sucked against the pan as Bill mentioned above.
Almost all the newer Milodon stuff comes with one now,,, probably copied Bill

[bill jones]

-I drill and tap the pins for a 10-32 threads about 3/8" deep, then I made a small slide hammer with a 10-32 end to jerk'm out and reuse them after I flatsand the parting surface.
-I also radius the hole within the cavity and the oil hole joint coming from the pump to the cavity to fit each other real nice and THEN do the flat sanding last.

[R.Brown]

"-I have never done the oil return back to the pan but I'll pull Ryan Brown's chain here and see if he will comment on that as I know he has done or still does do that. "

Sorry, I did not see this thread until now.

Returning the bypass oil into the pan has been a good deal, I do it on most pumps. Things you have to watch is where you direct the oil 'spray' back into the sump. A screen helps to diffuse the energy so that frothing is not a problem. This deal helps on oil temperature, and makes the bypass more responsive to spring pressure changes.

With a less restrictive bypass route, the bypass spring requirements change. To test it in the real world, I built an adjuster that goes on the pump, and with an access hole in the side of the pan I can reach in and turn a set screw to add or subtract the bypass valve spring pressure when dyno testing and feeling out a combination.

This started out as a debate on HV vs. Standard volume pumps, and Bill Jones hit it on the head. A properly built standard volume pump gets the nod every time. I am also a believer in 'porting' the oil galleries and generally putting a radius on every sharp edge where the oil travels thru the block. This includes the prep that Bill mentioned to pull the pins on the cap, along with working the feed holes to the groove behind the cam bearings, the path to the oil filter adaptor... etc. Generally about heavy hour worth of work with some special ball end carbide burrs. With attention to things like that, I have run the oil pressure down to as low as 30PSI (WFO MAX) on a 420 HP 2bbl engine without any negative effects.

Once you equip your engine dyno with oil flow meters on the feed and bypass, things start to make more and more sense.

Ryan