Dry sump thoughts

[DeathBySnuSnu]

I just almost dry sumped my scooter when last into it. But I did not.

I am cracking coolers. Never had that before. I am thinking the stack of fittings and the very short hoses on it this time are stressing the cooler or transferring vibrations.

So in order to move some parts around and have more flex to the hoses I am thinking of the dry sump again.

I dont have a problem with making the oil pump pickup from a tank.

The hold up is the scavenge pump system. Well not really the system but the scavenge pump itself.
I am looking at an electric pump. But I have no idea what kind of gpm it would need.
I am full hoovered and rocker squirters. Thin oil and lots of flow.

The cb bolt in 4 gear has a 21mm pressure and a 23mm scavenge. Seems like overkill for a scavenge. You certainly are not going to take out more than you put in. Their pressure bypass is into the sump, but mine is not.

It all makes me think just a couple gpm would be plenty.

Thoughts?
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[theKbStockpiler]

I thought that the oil pump has two parts ,one to feed the reservoir and one to feed the gallery. The expense of a premade reservoir was the big deciding factor as far as I was aware.
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[mcmscott]

You always run a larger scavenge than you do pump in a dry sump system, but I might be confused, you cannot afford a couple of synchros and a slider for your transaxle but you can afford some exotic oil system that may, or, may not benifit you???
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68 Ghia
67 T-1
65 Notch
02 Mexican beetle
74 Thing
15 Long travel rail
07 Nomad
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[slalombuggy]

Look at a Porsche 911 oil pump, the scavenge pump is HUGE, like 50-60mm, the pressure side is about 30 (it's been a few years since I rebuilt a 911 engine) The scavenge pump is always bigger so it keeps the internals clear of oil and since there is no restrictions, it does not build up pressure like the engine side of the pump.

Why not just make the hoses longer, put a loop in it to relieve the strain on the cooler instead of spending a few hundred dollars on a dry sump system?

brad

[Type 5 Joe]

My experience with a 2 gear dry sump system:

Even though the the scavenge pump was just a bit larger than the pressure pump...

It created a very measurable difference in crankcase pressure scavenge.

Positive piston displacement, it relieves the pressure on the backside of the pistons. This eases the force required to drive the piston on the power stroke...

Effectively freeing up power that would normally be consumed by fighting the internal pressure.

It takes longer to warm up the oil (10 quart), it also takes longer to cool it once heat saturated... Just running a dry sump system does not automatically mean cooler running : Myth.

I use it off-road... Having less oil windage on the spinning crank rods, and internal parts frees up power and makes a noticeable power difference.

I like jumping my buggy, and going through the rhythm sections of the dunes... The engine sings more like a 2 stroke motorcycle.

A regular VW engine would have the oil rapidly transferring from the bottom to the top of the case, hitting the spinning parts and slowing everything down, whipping the oil into a froth.

Then there's the benefits of running almost vertical on the side hills and up/down huge sand dunes for long periods... My engine gets oil to the bearings.

They need modification to work correctly... I have been down these roads.

I would ditch the electric pump idea.

If your going to use one, do it correctly and the benefits will be way more than just relieving stress on your oil lines. You can fix that or have that problem with any system.
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[mcmscott]

And it will probably cost more than 6 bucks
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There are no stupid questions, only stupid people,

68 Ghia
67 T-1
65 Notch
02 Mexican beetle
74 Thing
15 Long travel rail
07 Nomad
05 f-250

[Type 5 Joe]

Yes, it takes money to have fun... Lots of money, and I have to do all the labor myself.

It takes money to make mistakes

That's why they are called valuable lessons.
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[DeathBySnuSnu]

Well.
My pocket is not always full of money and there is not always time on my clock to do the things I want to do.

I found enough parts local to me and tossed the trans together and drove it to an event in three evenings after work.

Which does make a very very valid point......I really should be looking at going through the trans correctly instead of doing something else.

I do thank you Scott for your help though. I did not have the time or money right then and really did not want it to be so deep. But you knew exactly what had happened and pointed me in the right direction.

As this thing is a toy and winter is coming.....I will have some down time and time to save up money for it.

Do I need a dry sump? No I dont think so. That is why I did not do it to start with. Not looking to negative pressure the block/case just move oil. The moroso pump I had on a small block had 4 scavengers and one pressure. All external belt drive stuff, as in v8 race parts, nothing like this vw stuff. The scavengers in it each were smaller than the pressure side. But total of the 4 would be much larger. One pick up where the oil should be under acceleration and one where the oil should be with the chute out. The other two probably only pumped air where they were.

I was thinking of a system more for convenience.....much like a harley motorcycle engine has.

Ok so I should be looking at other ways to improve the oil line flex and cooler. I suppose I had these dry sump ideas stuck in my head from when I considered it before.
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[andy198712]

scavenge generaly wants to be twice the size of the pressure.

you always want a good supply of oil to the pressure pump, always.

if the scavenge was too small it would not keep up.

you have to think, the oil the scavenge is sucking up is hotter, aerated ect, the scavenge side has to work harder.

i nearly went this route and the pump i had was 60mm scavenge and 30mm pressure.
but after adding it all up the money just fly away a bit as all the fittings and extras and tbh hassle of drain back and packaging kinda put me off.

maybe one day.
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[Type 5 Joe]

From years of my own personal use of these:

The scavenge side does not have to be 2 times the volume on a VW engine...

The CB style pump keeps up just fine and actually draws a measurable vacum on the case.

A large pump creates clearance issues... The small CB pump has its own clearance issues... Something with a huge pump would need to run a tiny lower pulley... Or be belt driven off to the side like a V8 application.

The reason for multiple scavenge pumps on V8 applications is to allow you to scavenge port from multiple locations...

Usually a couple sump pick-ups and a couple valve cover outlets.

Usually the right side of the engine on a NASCAR or other oval track car.

There is a bit more to setting these systems up.

They need to be modified, you need more stuff than what they sell you.

I run a stock sized pulley too... That is a project to do correctly in itself.
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[DeathBySnuSnu]

Thanks Type 5 Joe.
I also used them on a v8 or two. But that is a whole different world.
I have not ever on a vw engine.
Not scared about the pulley. All that is hand made non shelf items anyway. Not scared of making a tank. Not scared of the pressure pump.
But it looks like if it was going to happen it would have to be a belt drive scavenger pump v8 style. Single point pick up.

But after all the input.....I do not think I am gonna go that way. All I really need is to move the pressure regulator somewhere else so I can get some line length/flex. I do not need to make it more complicated than it really needs to be.

Thanks for the thoughts.....tis why I asked.
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[mark tucker]

yes you want to pull out more than you put in,you have to or it will cavatate, also any air it lost in a dry sump thus no air going to bearings. if it's just the cooler issue cant you just add a ext cooler? I have one of those dry sump pumps somewhere,never looked at it hard, never pulled it appart,I think it was unused. Im not really fond of that type,I would rather run one off a cog belt if I was going dry sump, and not try to run it off that small tang on the end of the cam...witch has iissues with thick oil any way or the in/out pumps that have big gears and small gallys.