engine crankcase type vacuum pumps., do you need one?



engine crankcase type vacuum pumps., do you need one?

Postby grumpyvette » October 3rd, 2009, 9:05 am

The short answer is that, reducing the crank case pressure levels helps the piston rings seal and if the proper pressure levels are maintained it tends to improve power levels, and before someone brings it up, use of the emissions air pump is virtually worthless, unless you've got almost no blow-by or crank case pressure to begin with,as it just does not move sufficient air mass, to effectively drop the pressure levels enough to effect ring seal, now it might help on oil leak issues but it won,t prove effective on producing more hp,., the idea is to increase the ring seal, and reduce blow-bye,as you might know the rings use the pressure of both the compression stroke to start moving the rings out against the cylinder walls and the much higher pressures during combustion on the power stroke, the pressure above the rings forces them into the bottom of the piston groves, helping to maintain the seal and the space created, above the ring allows the pressure to get inside the piston groove over and behind the ring gap behind the ring forcing it out against the cylinder walls,this will obviously increase friction but in theory there is a layer of oil film the ring bearing surface rides on, that its downward movement ,is scraping an oil film partly off the cylinder wall as it moves downward, naturally if theres pressure below the rings, or excessive oil it tends to reduce the efficiency, so lowering the crank case pressure helps
ID also point out that one of the benefits of the DRY SUMP OIL SYSTEMS is that they tend to reduce crank case pressures as they act similar to a vacuum pump.
A vacuum pump has only one dominant function and that its to reduce effective crank case pressure that may have built up in the crankcase. In a well-built race engine, pressure builds up in the lower engine case from two main sources
1. combustion chamber pressure thats forced past the rings into the lower engines sump area,case , bye-passing the rings (especially low tension rings or rings,that don,t seat correctly on the cylinder walls, and/or ring flutter at high RPM.
2. Pressure is built up in the case by the pistons moving downward during intake and power strokes. By reducing crankcase pressures (as much as possible , bye in theory, creating a slight vacuum) the rings tend to have less oil and pressure and resistance under them reducing the ring seal to the piston grooves and piston to cylinder walll, especially when low tension, oil rings or improper piston ring groove clearances are used.
On a WET SUMP OIL SYSTEM, A vacuum pump will have very limited affect the engine's oil pressure, unless your running a very low pressure where its reducing the sump pressure enough to reduce the oil pumps ability to suck in oil, Id try to reduce sump air pressure no more than 1-2 psi lower than outside atmospheric pressure for that reason, as the 1-2 psi reduction in air pressure in the sump at any given rpm level is usually sufficient to reduce ring flutter issues(pumps don,t really suck, its the OUTSIDE AIR pressure in the sump forcing the oil into the oil pump pick up, as the gears in the oil pump reduce the pressure in the oil pump pick-up,) Oil pressure on the pressure side of the oil pump, is the result of the oil pump pumping warm oil against a flow restriction in the engine, keep in mind oil viscosity or thickness tends to be reduced as temperatures increase, and the clearances are mostly bearing,push rod, valve train and lifter bore engine clearances in the engine.
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now I could go into a long dissertation but the subjects been reasonably well covered in the quotes below, so rather than re-hash Ill just use the quoted info



some sources
http://www.rehermorrison.com/rmComponents.htm

http://www.gzmotorsports.com/complete-pump-kits.html

http://www.gzmotorsports.com/street-pump-kits.html






Quote: Originally posted on http://www.speeddemonmotorsports.com/Tech
Why a vacuum pump?

A vacuum pump will create a lower pressure zone relative to atmospheric pressure through continuous evacuation of air (since the system isn't sealed perfectly. Why would you want this? A crankcase vacuum reduces internal motor losses since the pistons have less to "work" against, improves ring seal, and improves oil control. On a stock car the PCV generally does the same thing - though it will not function very well in high load situations, and allows oil to get into the intake/cylinder heads. With an electric vacuum pump we can create the same depression, but over a wide variety of operating conditions, and without introduction oil into our engine induction system!

Tired of oil getting into your intake/engine through the PCV? Have a few oil or oil consumption issues that are driving you crazy? You might consider an electric vacuum pump

Vacuum pump - what?
You may or may not have heard of the concept of running a crankcase evac system. Generally there are three ways that you can do this.
Header/collector aspiration vacuum:
You have probably seen something like this before on a rail dragster. This consists of 2 tubes which fit into the header collectors at a 90 degree angle to the exhaust stream. The velocity/inertia of the exhaust gas will actually pull out gas through the tubes, which are connected to the crankcase (often through the valve-covers). This technique works well on open headered cars, but as ad backpressure (exhaust) the effeciency drops dramatically

Belt-drive vacuum pumps:
These systems use a vacuum pump which is powered through the engines belt system. This is most commonly used in dry-sump oiling systems. This allows for a great amount of vacuum to be generated (enough to maintain vacuum on even the largest motors). It requires custom bracketry and belt re-routing on a production sytle setup though.

Electric vacuum pumps:
These are by far the easiest to setup on a street vehicle. The can be mounted virtually anywhere, and only require a power, ground, and connectiont to the crank-case to operate.

Quote: Originally posted on http://www.competitionplus.com
Vacuum pumps are fast making a statement in drag racing, and with good reason. There's power in oiling systems. That's an obvious statement, given the fact that there's dozens of products on the market to control oil, from pans to scrapers, and everything in between. In the search for every exclusive ounce of horsepower, racers have sometimes gone to elaborate or unconventional means to accomplish oil control.


Alcohol racers are really enjoying using a vacuum pump. After one run, this is how much water, or moisture we pulled out of the drain can. Imagine this ending up in your oil.
The elimination of pressure in a crankcase has long been sought after. With parts swinging around and pistons going up and down, there's no possible way you can expect to make any power if the crankcase is plugged up. The engine has got to breath. Years ago people tried running hoses from the intake manifold down to the engine in an attempt to keep the crankcase under vacuum. One main benefit of vacuum is increased ring seal, which makes power because during the intake stroke, the combustion chamber is in vacuum trying to suck fuel out of the manifold. But it can also literally suck oil up past the rings. Keeping your crankcase under vacuum alleviates some of that. The problem with manifold vacuum, other than sometimes oil contamination with the fuel mixture, was that you only had vacuum at idle. Wide open at the end of the track, where you needed the power, there was little or no vacuum available. Enter the Vac-U-Pan system, which plumbed hoses from the header collector to the valve covers in an attempt to utilize exhaust pulses to create vacuum at the other end of the track. Truth of the matter though, is that they provide very little vacuum, even at best.

The next step in the evolution was the air evacuation pump from new car, which would suck vacuum. With that pump, the faster the engine spins, the more vacuum it produces. The people at Moroso, being the innovators that they are, knew that the OEM style pumps had their downfalls. For one, they didn't last. After all, they weren't designed for the rpm we were spinning them at. And two, they weren't rebuildable. Which meant that when they went bad, they became scrap metal. Moroso's fix was simple. Get out a clean sheet of paper and design one from scratch, which concluded with the manufacturing of their line of 3 and 4 vane Vacuum Pumps.


Moroso's Scott Hall explained the simplicity of their design and said, "There's very little moving parts inside this pump. We designed it that way so that it's relatively trouble-free."
Scott Hall, the sales engineer responsible with the design at Moroso says, "The three vane pump was our first piece and it works well with wet sump motors because it has more swept volume than the four vane, however, we added another vane to help the timing issue internally and we like to use that pump on motors using dry sump oil systems because it will also pull more vacuum". Hall does recommend you monitor the vacuum with either a gauge on your dash or one plumbed into a valve cover. "You don't want to pull more than around 14-15 inches of vacuum because than you're literally suck the oil out from the piston pins and valve guides, which can have dramatic consequences."

The nice part of their unit is the simplicity of it. Four allen head screws on the front of it and it comes right apart in your hand. From there it can be cleaned or rebuilt. The actual vanes are made of graphite for sealing purposes and upon first startup they tend to scrape and wear off until they're seated in. Hall recommends that after the first five minutes of running time, you take carb cleaner and spray it directly into the inlet. This will clean out any break in material that might be get caught in the vanes. "You could disassemble the pump and clean it out", says Hall, "but we've found that spraying cleaner into the inlet seems to work just as well."

Not having your crankshaft slapping through puddles of oil is the basis for most all oil system products today. Oil control is the key and dry sump systems, where the oil is in storage in a separate tank and fed to the motor by means of an external oil pump, is the ultimate for power and the reason you'll see them on most engines that demand every bit of power that can be squeezed from them. But in some cars where space is problem or maybe even finances dictate a wet sump system, running a vacuum pump in addition to any carefully designed oil pan devices will give you the most benefit you can derive from your combination.


There is one inlet and one outlet port built into the aluminum housing. While there is no pressure on either line, we still used #12 AN fittings and hose to plumb the pump.
As I said earlier, the last thing you want is the crank running through oil and here's a quick tip to check that on any engine using a deep, wet sump pan. First, know the height that the crank at its lowest part in the oil pan. Next with the oil pan on the bench, take quart cans of water, fluid, whatever, and fill the pan up to that point or slightly below it. However many quarts you counted is all the oil that you should put in the motor. Naturally, add one quart that's usually held up in the filter and if you'd like, maybe an extra half for oil stored throughout the block's oil passages.

Are there any downfalls to a vacuum pump? Not really, only if you count a slight loss in oil pressure because the vacuum is trying to pull oil out from the bearings. "This can easily be cured with an external pump, but without one", says Hall, "it's still not a problem because really what you want is oil flow, not so much oil pressure. If you could, a better gauge would be an oil flow gauge, because it would tell you that you have enough volume going to all the right places."

Another benefit to a vacuum pump is the ability to run low-tension oil rings. Ring drag is a horsepower killer. But with low tension rings, the possibility of the piston sucking oil out of the crankcase is amplified somewhat. By utilizing the vacuum pump to keep the crankcase under vacuum, that problem is rectified by closer balancing the pressure, or lack of, above and below the piston rings.


Those of you that run alcohol as a fuel, (not through your bodies), can attest to the nasty "mayonnaise" that's noticeable in your valve covers, especially on a cool day. This is due to the cooler running of alcohol that will literally suck the moisture out of the air, and mix it with the oil. While it's not a big problem, some have noted that more frequent oil changes are necessary with an alcohol fed fuel system. The vacuum pump will suck all that moisture right out. On a cool day, if you drain the dump tank hooked up to pump, it'll fill a spray can top full with water or moisture. Without it, think of making numerous runs while this moisture drains down and mixes with the oil. Easily you can see the problem.


The mandrel kit available from Moroso for either a small or big block Chevy is a quality part. It comes complete with pulleys for either a standard v-belt or a toothed belt.
The Moroso pump comes complete with an aluminum adjustment bracket that bolts to the back of the pump. But other than that, some type of fabrication is necessary to mount it. "Most guys bolt it right to their motor plate if they have one", Hall says, "but to make dedicated bracket that would fit everyone's application would be almost impossible. Plus we figured that most people who buy one would have some kind of fabrication skills anyway and it'd be better for them to mount it where ever they could".

Another must have for this is Moroso's Part #63845, which is a drive mandrel for a small block Chevy, while part #63844 fits the big block. It comes complete with spacers and pulleys to drive the pump off the crankshaft. We opted to run a toothed belt rather than a v-belt because it requires less tension on the belt. With a v-belt, it's necessary to keep belt tension so that it doesn't slip, and having the pulley driven some 3 or 4 inches off the end of the crank could cause some flex in the mandrel. We also decided to run steel braided line, but it can be plumbed with oil resistant #12 line as well, as there is no pressure, obviously, on the hose or fittings.

"The ultimate from an engineering standpoint", says Hall, "is to run a dry sump, and I recommend it where ever I can, but regardless everyone should be running a vacuum pump. From a horsepower standpoint, you should see 2-5% increase, and based on the cost of the unit, that's a cheap way to pick it up". Another very good reason for running a vacuum pump.
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: engine crankcase type vacuum pumps., do you need one?

Postby guysmontess » October 3rd, 2009, 2:01 pm

Thanks for the info Grumpy.I've got my car put away for another Canadian winter,so this gives a person too much time to think on things,like the next possible rebuild.I think I have a pretty good combo with the Brodix Race Rite heads & custom ground solid roller cam,but I think that different pistons with low tension rings and a vacuum pump would be beneficial.Now that I understand more about static & dynamic compression and quench height,the more I think that I could squeeze more HP out of my 468 bbc.As I am learning more all the time,thanks to forums such as this one,I think that a bit more static compression,a little less quench height,low tension rings used in conjunction with a vacuum pump,could be quite do-able,and still have fairly good street manners.But this is all just speculation for now,I've got a long winter ahead of me !!!
Guy
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Re: engine crankcase type vacuum pumps., do you need one?

Postby guysmontess » October 3rd, 2009, 3:33 pm

I have question Grumpy;I have seen belt driven vacuum pumps,but never an electric one.Got any info on these ???
Guy
1986 Monte Carlo SS 468 Big Block,UDHarold Custom Solid Roller Cam,.668 Lift,243/249 Dur. @ 0.050,Isky EZ Roll Lifters,Manton Pushrods,Jesel Rockers,Doug Nash 4+1 5 speed,Hurst Inline Shifter,Ford 9 Inch w/3.00:1 gear
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Re: engine crankcase type vacuum pumps., do you need one?

Postby grumpyvette » October 3rd, 2009, 5:55 pm

guysmontess wrote:I have question Grumpy;I have seen belt driven vacuum pumps,but never an electric one.Got any info on these ???
Guy


theres NO electric vacuum pumps that IM aware of that are not a TOTAL JOKE, designed more to thin your wallet than significantly reduce crank case pressure, think it thru, it will take approximately a 2-3hp pump turning the typical 1700rpm to make any real significant difference in the vacuum readings at the 5000rpm-6500rpm range where they really make gains, that 2-3 hp off a serpentine belt drive off the crank is negligible, but a 2-3hp 12 volt electric motor will use most or all of your alternator out put and weight easily 40lbs plus

200 amps x 12 volts= 2400 watts

you can find the horsepower. The easiest way is to determine watts by multiplying amps X volts. Next multiply watts by .00134 and you have horsepower.

2400 watts X .00134 = 3.216 horsepower

most alternators can,t support a 200 amp draw even for a few minutes and still run a cars ignition effectively


you would be far better off installing a dry sump oil system

http://www.lindseyracing.com/LR/Parts/LRDSUMP.html

viewtopic.php?f=54&t=1058

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http://en.wikipedia.org/wiki/PCV_valve

http://www.tegger.com/hondafaq/pcv-replace/

http://www.autoshop101.com/forms/h63.pdf

http://www.aa1car.com/library/pcv.htm

step one

make sure the pcv valve is functioning correctly
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: engine crankcase type vacuum pumps., do you need one?

Postby grumpyvette » March 25th, 2011, 7:44 pm

if your getting oil mist spray or oil mist from the breathers, BLOW-BY is frequently the cause when you rev the engine or something else?
As I'm sure your aware those breathers on valve covers need to have a baffle design to reduce oil traveling along with the vapors and on race cars the breather are frequently linked with a one way pvc style valve to header collectors , but can be linked to a belt driven vacuum pump, or a PCV system of some type if your rings are allowing a good bit of crank case pressure to build up resulting in constant oil mist from the valve cover breathers

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http://www.summitracing.com/parts/SUM-120108/

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BTW we found we could just insert one or two stainless steel scrub pads in the breather tube space, (A and B) as that will absolutely control any air flow turbulence, that tends to drag oil out the breathers and make the engine a oil soak mess.
I know we did that on road race cars, for oil control on crank case breathers, and it drastically improved the flow back rates and controlled the formation of oil foam, allowing the oil to flow back with a noticeable reduction in air trapped in the oil.
these threads may help

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viewtopic.php?f=87&t=4636&p=12610&hilit=breathers#p12610

/viewtopic.php?f=52&t=2005&p=5328&hilit=+valve+vacuum+PVC#p5328
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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