Low volume oil pump

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1972ho
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Low volume oil pump

Post by 1972ho »

Any of you run any of the low volume wet sump oil pumps in your stock oil pan and if so does the pressure fluctuate a little at idle about 5 to 10 psi at around 1500 rpm idle speed mine does but a standard volume pump does not I’m thinking it’s just because it has a hard time keeping up up with the leakage in the engine at idle.
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Re: Low volume oil pump

Post by rebelyell »

1972ho wrote: Sat Apr 10, 2021 1:15 pm Any of you run any of the low volume wet sump oil pumps in your stock oil pan and if so does the pressure fluctuate a little at idle about 5 to 10 psi at around 1500 rpm idle speed mine does but a standard volume pump does not I’m thinking it’s just because it has a hard time keeping up up with the leakage in the engine at idle.
? What is part number of your "low volume OP" ??

? What is OD of your pickup tube (typically 5/8" or 3/4") on your "low volume OP" ??

? Are you working on an LS ?? ... ? Which motor are you working on ?
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Re: Low volume oil pump

Post by rustbucket79 »

We did a test on a mild 400 sbc first with a high volume then a standard volume oil pump, changing from BR oil to 10w 30 synthetic oil. The results? No gains.
1972ho
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Re: Low volume oil pump

Post by 1972ho »

This pump is a modified 351cleveland standard volume pump with a modified lobe and a bronze spacer installed to take up the clearance I believe it was done by Stewart.
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Re: Low volume oil pump

Post by Walter R. Malik »

1972ho wrote: Sat Apr 10, 2021 4:48 pm This pump is a modified 351cleveland standard volume pump with a modified lobe and a bronze spacer installed to take up the clearance I believe it was done by Stewart.
A one inch thick Gerotor has been plenty of oil for FE fords for years ... I have personally machined many Ford oil pumps, (351W, 351C & M and 429/460), to that one inch thick measurement with absolutely no issues, if all the clearances within the engine are in spec.
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Re: Low volume oil pump

Post by swampbuggy »

1972ho...What is the I.D. of the line from the engine oil port to the gauge ( mechanical gauge i am assuming). ? Mark H.
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Re: Low volume oil pump

Post by nhrastocker »

1972ho wrote: Sat Apr 10, 2021 4:48 pm This pump is a modified 351cleveland standard volume pump with a modified lobe and a bronze spacer installed to take up the clearance I believe it was done by Stewart.
If the pump was built by Larry Stewart, they work great and make power. Take the pump apart and check the bypass to make sure nothing is sticking and it is free to move. I have the same happen to me with a Schumann Low Volume oil pump and was a the bypass sticking. After cleaning it up, the problem went away.
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Re: Low volume oil pump

Post by 1972ho »

Nhrastocker I have already caught that bypass valve sticking and when I pulled it apart it was stuck open so I cleaned it out and ran some emery cloth around in it and the valve itself and it was really free to move when I put it back.I just wonder why the oil pressure does this little fluctuations cycling stuff idle.Does your oil pressure cycle are is it rock solid I know some it is the way the engine idles because of the camshaft is really radical.
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Re: Low volume oil pump

Post by rebelrouser »

Most pumps have the relief valve spring calibrated at the rpm they are going to run. Most stock oil pumps pressure spec is usually a certain pressure at a certain rpm, like around 2,000 rpm. It is a waste of HP to run a pump at high rpm and then just have a large part of the output simply dumped into the pan. If it is a low volume pump the pump may not keep up at idle, especially when hot. My old race engine with aluminum rods held 100 psi cold, and 20 lbs up the return road after a run at idle, just touch the throttle and it went to 70 psi, which is where I wanted it to be. I had an externally adjustable pressure relief valve, and that is where it settled in at. I never worry about idle oil pressure, it is under a load at rpm that I pay attention to.
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Re: Low volume oil pump

Post by Tuner »

If you have a large enough line (1/4" or larger), so there is very little restriction from the engine to the gauge, the gauge needle will swing as fast as the tach needle from idle up to whatever the pressure relief bypass is set. If it doesn't go below 5 psi at 500 RPM or so I wouldn't sweat it as long as it jumps up with RPM.

The 1/8" nylon line that comes with a new gauge will make the gauge very slow to respond.

I changed a 10 foot line from 1/8" to 1/4" and about choked to see the BBC in my boat only had 5 PSI at ~500 RPM idle when the oil was 240 deg. It had been that way for 2 racing seasons with no ill effects.
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Re: Low volume oil pump

Post by swampbuggy »

Yes Tuner, this is why i ask the O.P. the question i did, I know for a fact that with a large I.D. line to the gauge you will see the gauge bouncing / fluctuating when the oil gets to full temp. I should include that what i am testifying to is a Ford 4.2 L V-6, #6 line--3/8" I.D., Auto-Meter Mechanical Gauge. BTW the large line came about by accident, when i attempted to buy the hardware that is what was available to get me going. I am wondering if the results would be the same with a Dry-Sump System ?? Mark H.
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Re: Low volume oil pump

Post by benno318 »

just in the process of assembling it now, but i have purchased a low volume LS pump for a customers production circuit race car.

he had not long bought it from interstate, did a few race meetings with it (engine already built by who knows who???) he wanted to get some more power from it - he had to remove the heads for a valve job and we sent the cam for doctor report - it already had a double row chain - the 2 alloy oil pump spacers, the one to the oil feed passage to the block was upside down which half blocked the feed from the pump!

unbelievable... no issues from it luckily, even 12 months later a full stripdown bearings all looked good so hence the decision to try the low volume pump
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Re: Low volume oil pump

Post by swampbuggy »

I should add this information to my remarks above, the oil pressure gauge only bounces at "Idle" and it bounces about 20 P.S.I., 20 to 40 and stabilizes with increased RPM's, Mark H.
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Re: Low volume oil pump

Post by swampbuggy »

Edit: Stabilizes to appx. 70 P.S.I. at 3500 R.P.M.'s, Mark H.
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Re: Low volume oil pump

Post by 1972ho »

Do you think if I put a gauge right at the front of the block at the pumps first discharge and watch the one at the rear of the block if that would tell me anything if the one at front would not be fluctuating and the one at the rear would be.
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