electric vacuum pump

[rayruner]

I'm going to put a vacuum in the oil pan on my 3100, can't deside which electric vacuum pump to use, though i would ask on here as to the best one. thanks in advance

[trotterlg]

You know that if you pull a vacuum in the engine there is no pressure to push the oil up to the oil pump right? Larry

[Superdave]

lol, Larry that's not true.


OP, the electric ones draw a ton of power. Check out the belt driven ones, they seem to do a better job. Both are very pricey though.

[caffeine]

Isn't there normally vacuum in the crankcase due to PCV?

[Superdave]

Nope, it just vents the pressure from blowby (and sucks up oil fumes into the intake).

The OP wants to draw a vacuum on the crank case, that takes some good power. IIRC 5" of vacuum is about right, some guys go more but it all really depends on how well the engine is sealed. There are some nice performance gains that come with it.


The old school way is to use slashcuts in the exhaust, it never really pulls more than 1" at the most with open headers but even that's an improvement over the PCV system. It does make the car smoke at WOT though, and it will murder o2 sensors if they are after the slashcuts.

[trotterlg]

I am right on this one, you cannot pull a vacuum in a vacuum, the only way the oil gets into the pump is the air pressure, if there is a vacuum in the crankcase the pump cannot pull the oil up. Worked on an aircraft program once, flew a recip to 71,000 feet, 2% atmosphere there, this is a big problem. Larry

[trotterlg]

OK, I do have to admit that this would be an extreme case, but if you pulled 15 inches of vacuum in the crankcase you could never deliver oil to the engine. Also, there is a problem with oil boiling at extremely low pressure, probably something not many will encounter, but somethign that can happen in extreme conditions, mostly when trying to operate recip engines at really high altitudes. Interesting stuff however. Larry

[pocket-rocket]

If that were true I don't think roots type superchargers would work at high altitudes, and that's why they were developed, to boost performance at altitude.

If our engines used a diaphragm type pump I could see it being a problem.

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[Superdave]

I am right on this one, you cannot pull a vacuum in a vacuum, the only way the oil gets into the pump is the air pressure, if there is a vacuum in the crankcase the pump cannot pull the oil up. Worked on an aircraft program once, flew a recip to 71,000 feet, 2% atmosphere there, this is a big problem. Larry

no, sorry.

People have been running mechanical and electric vacuum pumps on engines for a long time on race engines.

Car Craft had mixed results but there is good info in this article: http://www.carcraft.com/techarticles...uum_pump_test/

More info here: http://www.starvacuumpumps.com/about/

[rayruner]

vacuum pump

Thanks for the replys, I already got a vacuum in the oil pan using my pvc, the car is a malibu 3100 with a rsm blower, i had a audi electric pump installed,for under boost, that was used and didn't last to long, the reason i ask, looking for somethi,ng better

[trotterlg]

is.jpgLots of ford diesels have belt driven pumps on them, that should be dead easy. Some Isuzu diesels had vacuum pumps built ont he rear of the alternator also. Larry

http://www.ebay.com/itm/ALTERNATOR-Isuzu-Medium-Duty-Truck-NPR-GM-5-7L-v8-93-97-PREMIUM-w-Vacuum-Pump-/230551250872?pt=Other_Vehicle_Parts&hash=item35adece7b8&vxp=mtr#ht_4483wt_1161

[geoffinbc]

You can pull a vacuum inside the engine and there will be no change in oil delivery. However you will see a change in the gauge. Reason being is the inlet of the pump and the outlet like the clearances in the bearings, lifters, rockers and so on will also all be under the same pressure or lack there of (vacuum). The gauge however compares pressure on the inside of the oil galleries to the atmosphere. So unless you have a fancy gauge with a reference port or somehow put an electronic sender inside the engine your gauge will be off.

This is the same principal with multi port fuel injectors. Many think that the vacuum line connected to the regulator is there to increase pressure when you floor the gas. While this is true when referencing the atmosphere, if you reference the pressure inside the intake manifold the pressure never actually changes.

[trotterlg]

I know it is hard to get your mind around, but if you have a complete vacuum in the crankcase (as in 30 inches of mercury) you will not be able to pump any oil. There is simply nothing to push the oil up to the pump. Now I know you will never have that kind of vacuum in this kind of engine, but there are cases where it can occur, like at 70 or 80,000 feet, then, the only way to get oil pressure is to put a pump at the bottom of the crankcase and rely on gravity to feed the oil, gravity seldom fails. Larry

[geoffinbc]

If you have a complete vacuum in the crankcase the oil will boil so you have bigger problems. Here on the ground in a normal engine your oil flow and pressure (when referencing the crankcase) will not change.

[The Hulk!]

Is this Larry guy serious?

I ran a vac pump on my Cadillac escalade pulled 12 inches made 12whp and makes the intake nice and clean... I loved it only problem is it didn't like cold weather.... To the op I have said vacuum pump kit that you can buy off me and retrofit to your app lmk

Jordan