Landracing Forum
Tech Information => Technical Discussion => Topic started by: Rocket123 on July 16, 2014, 11:27:40 AM
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First time with a dry sump. A rather expensive lesson trying to make wet sump work. I thought I bought a 4 stage pump but it is only 3 wanted to run 3 to the pan and 1 to the valve cover. What I am wondering is if I could split 1 line probably the one going to the front of the pan and run it to the breather also. help is appreciated.
Thank You, Rocket
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another option might be to plumb the valve cover lines to the pan or to the fuel pump block off--
-no matter what you do--the stage you split is going to feed from the path of least resistance
I would just take a stage upstairs, if you feel like you have to-- but I have no personal knowledge, of going upstairs with a stage---
I run a four stage just like you with 3 on the pan and 1 pressure I make sure it can drain back as well as I can get it to and just run 16 quarts at B'ville
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sounds like I didn't know how to count stages and I do have a 4 stage pump 3 scavenge and 1 supply. plumbing the valve cover to the fuel pump block off plate sounds good to me, any other input welcome.
Thank You, Rocket
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I am assuming that you intend to seal off the lifter valley and suction the upper end oil back to the pump.
I would suggest that you pull a AN 12 from the valley and tie it into a AN 10 from the front area of the oil pan. If the pan already has a AN 12, use a reducer.
On the other hand you don't want to pull any more air than you have to into the Dry Sump Tank. Make sure your tank has a anti-aeration screen in it.
On my BBC, I mounted the magneto in front and built a 3/4" copper manifold which lays tight to the lifter valley and is "hung" from the bottom of the intake manifold
and runs from front to back and then turns up thru the now vacant distributor hole terminating to the An 12 line.
Don't forget to run inline screen filters on each suction line BEFORE the pump and a Big filter on the pressure side of the pump.
Bob Drury
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Bob brings up a good point---what are you trying to accomplish?
HP or removing oil from up stairs?
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basically what we are trying to do is control blow by out the valve covers. our lifter valley is not plugged off. we do not want to put more air into the tank. maybe with a dry sump there isnt as much blow by. Would it still be a good idea to plumb the valve covers to the fuel pump block off plate.
Thanks a lot, Rocket
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you want to create a vacuum---and you should the whole eng should be sealed so that it can pull a vacuum---if you have a leak you are just going to move the blow by to the dry sump tank---my lips are sealed as to why I know this first hand---it does create NEW problems :-D
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got it. valve cover breathers sealed and 3 scavenge lines to the pan. TY
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I started to do the same thing (sealing engine). Then thought about what would happen if it holed a piston. I can visualize the pressure blowing out valve cover and pan gaskets and oil on the headers with it. Check valves on the vents should let a vacuum be pulled and still release excess pressure.
YMMV
Ron
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one of the benefits of dry sump---there is very little oil other than in the sump tank---I have not burned a piston yet---but mount a vacuum gauge to the pan lifter galley area---if you start getting blow by you will know it before it blows--- if you have an idiot light on the PAN vacuum or happen to be watching the gauge rather than the track!! :-P
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Not meaning to argue with you, Sparky.
Aviad says BB Chev flows about 12 gallons per minute at high RPM. That's about 25 ounces per second that's being thrown around in the engine. To me that is enough oil to make a mess. :-(
Ron
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good point!
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A vacuum gauge connected to the engine valley/sump is an essential item to properly develop a dry sump system to "evacuate" blow-by. Don't be surprised if it takes WAY more pump stages or capacity than you think to create a vacuum. You will need to reverse your crank seals (think about it . . .) OR run seals with a "dual-lip". High levels of vacuum create strange sealing problems within engines. Think carefully about using gaskets Vs. a sealant, ie: RTV.
Serious reduction of the internal "oil mass", MAY create weird wear issues within the engine. Be sure to do a thorough evaluation of components & wear patterns during teardowns. This is VERY important and should not be ignored.
BTW, some engines respond very well to this, others just don't seem to respond with any bhp pickup.
Check out a current WINSTON CUP engine, IF you can get close enough for a picture. Dismiss publicity photos, NOBODY gives away ideas at that level. CUP engines circa 2002 ran 5 stage pumps, 4 scavenge & 1 pressure. And all sorts of oil flow reduction. These engines had 0/1% hot leakdown and pulled at least 5" of crankcase vacuum. Consider for a moment that in 1992 the same engines had 4/7 cfm of dynamic blow-by at WOT on the dyno in the power range . . . . . . .
Think seriously about blow-by reduction in the first place. Blow-by is LOST combustion pressure, ie: horsepower. Do what is necessary to get it sealed up.
:cheers:
Fordboy
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Does it matter where I put the oil tank, how far can the pump pull the supply oil? Thank You
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also any suggestions on line size was going to use 12an supply with 12 an scavenge to the pump and 16 an from pump to tank. Thanks again
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Assuming you meant to say "a pair of -12 scavenge lines", your sizes look okay to me (excepting some very small or large engine with unusual oil flow rates).
In general, it's best to avoid the pressure pump "pulling", if possible. Gravity feed is best, to assure liquid oil always at the pump (during startup, etc.). Although my reason for using dry sump was unusual (avoid pumping any air while front of tractor danced nervously in the air!), I had the tank (funnel-shaped bottom) above the pump and close to it. [This photo was right after doing the dry sump setup. The S-shaped hose wanted to trap some air in its high spot, so I raised the tank a couple inches and changed to a very short all-downhill hose]. It served me well for a number of seasons after that.
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Assuming you meant to say "a pair of -12 scavenge lines", your sizes look okay to me (excepting some very small or large engine with unusual oil flow rates).
In general, it's best to avoid the pressure pump "pulling", if possible. Gravity feed is best, to assure liquid oil always at the pump (during startup, etc.). Although my reason for using dry sump was unusual (avoid pumping any air while front of tractor danced nervously in the air!), I had the tank (funnel-shaped bottom) above the pump and close to it. [This photo was right after doing the dry sump setup. The S-shaped hose wanted to trap some air in its high spot, so I raised the tank a couple inches and changed to a very short all-downhill hose]. It served me well for a number of seasons after that.
X2.
Your dry sump tank should always gravity feed the pump inlet. If the pump has to "suck" the oil, your pump pressure output will be reduced by the amount of suction. Remember, a pump is only a "differential pressure device". Ie: with a pump pressure differential of 60 psi, with gravity flow of 1 psi output = 61 psi. With a suction of -5 psi, output falls to 55 psi. Line size has a HUGE impact on oil flow when the oil is cold. Pressure pump inlet size should be -12 minimum, maybe -16 if the run is long.
:cheers:
Fordboy
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99% of all dry sump pumps are gear type and although gear pumps have pretty good ability to suck, they should not be put into a situation that requires them suck, they should always have a positive pressure head on their inlet (talking about the pressure section). That means the oil level in the tank needs to be above the pump inlet, the higher the better, the hose from the tank to the pump should be large, -16 at least , even if you have to use a reducer at the end of the hose to fit the pump inlet port, and short, and direct. The oil tank needs to be well vented. Although Fordboy is correct that a pump is a differential device the out put pressure of the pump is (should be) controlled by the pressure relief valve that is connected to the pump outlet, if the situation occurred that he describes, pump out let pressure drops because of a reduction of the inlet pressure, then your pump is undersized. You should have, under all conditions oil flow from the pressure control relief valve to insure you maintain your target oil pressure which is an indication of proper oil flow to the engine. A note regarding Fordboys comment about the reduction of the inlet pressure by 5 psi, which would make the pump inlet pressure 9.7 psi absolute, at this inlet pressure and if the pump is turning at 2-4000 rpm you will most likely cavitate the pump, which means there will be air entrapped as "bubbles" in the outlet flow and air is not a good lubricant.
I also need to make a comment regarding filtration, if you check the NASCAR set ups you will see that they use a large and fine (usually below 10 micron) filter in the return line from the scavenger pumps to the reservoir, they also use the small screen filters that Bob Drury recommended but these only catch rock, birds and small children so any trash that may come out of the engine will then be sent to the reservoir and then to the high pressure pump. This contamination can, will, cause the high pressure pump to degrade and eventually not be able to provide sufficient flow to maintain system pressure. Having a filter on the pressure section out let is not a bad idea as it can (will) catch the gear teeth from the pump when if fails because it ingested some large chunk of metal that was not filtered out of the scavenge return flow. Buddy has been using a large 6 micron filter on the scavenge return line on the Flatcad with great success.
Rex