Any disadvantages to running a vaccuum pump? (for oil)

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MOPARMAGA

MOPARMAGA

" The other hard member"
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I know of a couple pro's for running these. Cleaner oil, less windage, more horsepower
I'm looking at aerospace engineering they have a kit for big block mopar.
But are there any con's? & if anyone has anymore pro's to add, please do !
Thanks.
 
As my dad always said "the parts you don't add, don't cause you no trouble"
 
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You have to get the engine sealed, TIGHT. @gregsdart was dealing with rear crank seal issues, but I forget how much vacuum he is pulling.

If you don’t run thin rings, which is 1mm or less, back cut them and use gas ports, you won’t get the biggest power increase from pan vacuum.

And, and this is a big AND, the more vacuum you pull, the more it changes the surface finish on the cylinder walls, including cross hatch angle. So you have to be understanding of that.

There is more to crank case vacuum than just bolting on a pump. You need to consider everything it affects. There is power in it for sure.
 
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I always like to keep things on the simple side so I’ve never ran one. Maybe if I was running Pro Stock I would reconsider. Lol.
 
I run around 15"Hg of crankcase vacuum street/strip. Main seals installed backwards, no problems. Also no leaks. Even had an incident once where i melted a sight gauge tube in my oil sump, didn't leak oil until after I turned off the engine.

Oil pressure on the gauge does go down as vacuum goes up, but that's mis-leading as the oil pressure gauge is measuring the difference between oil pressure and ambient air pressure outside the crankcase. If the oil pressure gauge was located inside the crankcase (referencing crankcase pressure instead of ambient), indicated pressure would not change. Basically the loss of gauge oil pressure due to crankcase vacuum is an illusion.

Grant
 
weedburner said:
I run around 15"Hg of crankcase vacuum street/strip. Main seals installed backwards, no problems. Also no leaks. Even had an incident once where i melted a sight gauge tube in my oil sump, didn't leak oil until after I turned off the engine.

Oil pressure on the gauge does go down as vacuum goes up, but that's mis-leading as the oil pressure gauge is measuring the difference between oil pressure and ambient air pressure outside the crankcase. If the oil pressure gauge was located inside the crankcase (referencing crankcase pressure instead of ambient), indicated pressure would not change. Basically the loss of gauge oil pressure due to crankcase vacuum is an illusion.

Grant
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Thanks Grant
 
yellow rose said:
You have to get the engine sealed, TIGHT. @gregsdart was dealing with rear crank seal issues, but I forget how much vacuum he is pulling.

If you don’t run thin rings, which is 1mm or less, back cut them and use gas ports, you won’t get the biggest power increase from pan vacuum.

And, and this is a big AND, the more vacuum you pull, the more it changes the surface finish on the cylinder walls, including cross hatch angle. So you have to be understanding of that.

There is more to crank case vacuum than just bolting on a pump. You need to consider everything it affects. There is power in it for sure.
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Okay thanks Tim, I'll talk with my builder a little more about them, he runs one with his low 10 small block all steel dart & swears by them, no oil leaks, changes the oil 1 time a season & said he won't race without 1
 
yellow rose said:
You have to get the engine sealed, TIGHT. @gregsdart was dealing with rear crank seal issues, but I forget how much vacuum he is pulling.

If you don’t run thin rings, which is 1mm or less, back cut them and use gas ports, you won’t get the biggest power increase from pan vacuum.

And, and this is a big AND, the more vacuum you pull, the more it changes the surface finish on the cylinder walls, including cross hatch angle. So you have to be understanding of that.

There is more to crank case vacuum than just bolting on a pump. You need to consider everything it affects. There is power in it for sure.
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Kinda disagree , know some guys that are running them , added after the engine build , no oil related problems ----------??
I`m currently getting enough vacuum out of one evac tube so far , even sucks at idle .------no pcv valve .
 
weedburner said:
Oil pressure on the gauge does go down as vacuum goes up, but that's mis-leading as the oil pressure gauge is measuring the difference between oil pressure and ambient air pressure outside the crankcase. If the oil pressure gauge was located inside the crankcase (referencing crankcase pressure instead of ambient), indicated pressure would not change. Basically the loss of gauge oil pressure due to crankcase vacuum is an illusion.

Grant
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I'm glad someone else mentioned this. Actual pressure cannot and will not go down due to crankcase vac alone.
 
Phreakish said:
I'm glad someone else mentioned this. Actual pressure cannot and will not go down due to crankcase vac alone.
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I'm not arguing with this at all.......just learning......
So the "reading" on the oil pressure gauge goes down when crank case pressure turns to a Vac.........Does that mean, that if you had high crank case pressure.....say in a boosted situation, with bad rings blowing into the crank case(no vac system installed). That the oil pressure gauge would read higher at that moment?

When the pressure gauge goes down under crank case vac.......how much does the gauge read...less.......a pound? 10? More???
 
Cudafever said:
I'm not arguing with this at all.......just learning......
So the reading on the oil pressure gauge goes down when crank case pressure turns to a Vac.........Does that mean, that if you had high crank case pressure.....say in a boosted situation, with bad rings blowing into the crank case(no vac system installed). That the oil pressure gauge would read higher at that moment.

When the pressure gauge goes down under crank case vac.......how much does the gauge read...less.......a pound? 10? More???
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Yes, excessive crankcase pressure would make for a higher reading. But the higher the crank pressure, the more oil is going to be blowing out of the seals, pcv, breathers, etc.

The lower reading caused by crank vac will depend on the actual crank vacuum. 30" (hg) of vac is good for about 15psi, so 10" of vac would lower the reading by about 5psi.

The entire crankcase is at the same vacuum, so the oil pickup sees vac and so do the oil clearances, so the pump is still 'adding' the same pressure between the sump and the clearances. Now, if an engine is somehow very very heavily baffled, there could be a difference in the vac reading in the valve covers versus the sump, but it wouldn't be much - maybe a couple inches of vac.
 
Food for thought, but more expensive gauges can read what's called 'absolute pressure', which won't change with vac or pressure in the crankcase. It will measure only the 'deadhead' pressure at the sending port. But these types of gauges tend to be far spendier (the measuring device has a vacuum chamber inside it which requires calibration), so I'm not sure many oil pressure gauges measure absolute. Instead most measure 'gauge' pressure, which is the difference between atmospheric and the referenced port.

Some folks may actually have absolute oil pressure gauges, but the types of people to use them will likely know exactly what they're measuring.
 
Phreakish said:
Food for thought, but more expensive gauges can read what's called 'absolute pressure', which won't change with vac or pressure in the crankcase. It will measure only the 'deadhead' pressure at the sending port. But these types of gauges tend to be far spendier (the measuring device has a vacuum chamber inside it which requires calibration), so I'm not sure many oil pressure gauges measure absolute. Instead most measure 'gauge' pressure, which is the difference between atmospheric and the referenced port.

Some folks may actually have absolute oil pressure gauges, but the types of people to use them will likely know exactly what they're measuring.
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Everything for my car has been expensive (to me) so it won't hurt to go with that type of gauge, thanks for that info
 
MOPARMAGA said:
Everything for my car has been expensive (to me) so it won't hurt to go with that type of gauge, thanks for that info
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If the gauge need calibration, that mean that it will need re-calibration or check for accuracy. I think i would keep with the standard gauge and know that it will fall with X amount of vac.

You would need a data logger, and then, logging oil pressure, to even be able to catch this change.
 
Cudafever said:
If the gauge need calibration, that mean that it will need re-calibration or check for accuracy. I think i would keep with the standard gauge and know that it will fall with X amount of vac.

You would need a data logger, and then, logging oil pressure, to even be able to catch this change.
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I have no idea how to do a data log, lol.
Thank you for the advice
 
Not claiming to be an expert by any matter of means but why not just go with a nice little crankcase evac system relieve the pressure and call it good
 
I'm guessing one could get a liquid filled oil pressure gauge, remove the fill plug, then plumb the fill plug opening to the crankcase. Not worth the trouble to me.

Grant
 
weedburner said:
I'm guessing one could get a liquid filled oil pressure gauge, remove the fill plug, then plumb the fill plug opening to the crankcase. Not worth the trouble to me.

Grant
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Sure is abunch of b.s. in these threads !,
 
MOPARMAGA said:
I know of a couple pro's for running these. Cleaner oil, less windage, more horsepower
I'm looking at aerospace engineering they have a kit for big block mopar.
But are there any con's? & if anyone has anymore pro's to add, please do !
Thanks.
Click to expand...
I have heard that too much vacuum can mess with wrist pin oiling.
I'm gonna give a pump a try on my motor.

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