Dumb questions about dry sump use...

[vwjim]

As forums prevent you searching for three letter words, like "dry" and "oil" I've not found the answer to what is probably a really dump questions...

So if you have a dry sump engine with no dipstick...

1. How do you check the oil level? Do you have a sight gauge on your tank and check with the engine running at idle? Or some other method?

2. I assume the larger the oil capacity the better? So aim for the same as a stock engine plus a big deep sump would have

3. Tank location? Where's best? On the shelf behind the rear seat inside the Bug? Oil hoses would be quite long, but it's safe in there and plenty of space. I know 911's had it built into the RHS rear wing area, but I don't think there's enough space for it like that on a Bug.

Thanks

[twodollardoug]

I have a sight tube. My tank holds 10 - 12 quarts. The bottom of the tank should be above the oil pump.

[ONEBADBUG]

What I used to do was; rev the motor and watch the level in the tank. It would go down as you revved, so just made sure it had enough. Never did just figure out what volume it took to fill it up. The problem is, sometimes there is some oil in the block. sometimes there isn't.

[woodsbuggy1]

I run a dry sump in my offroad buggy, I built my own tank and have a sight gauge and run 6qts of oil. My tank sits on the floor of the buggy and has a ball valve to keep the oil from filling engine ( it is fine for a few hours but will drain overnight). I use a CB pump and the scavenge side is larger than pressure side of pump so I could probably run a smaller tank with less oil and still be fine. Also after hearing of issues from others; I use hydraulic hose on suction side(to prevent hose from collapsing) and Summit clampless hose and fittings on pressure side.
Kenric

[vwjim]

I run a dry sump in my offroad buggy, I built my own tank and have a sight gauge and run 6qts of oil. My tank sits on the floor of the buggy and has a ball valve to keep the oil from filling engine ( it is fine for a few hours but will drain overnight). I use a CB pump and the scavenge side is larger than pressure side of pump so I could probably run a smaller tank with less oil and still be fine. Also after hearing of issues from others; I use hydraulic hose on suction side(to prevent hose from collapsing) and Summit clampless hose and fittings on pressure side.
Kenric

Do you have details of the ball valve?

Thanks all.

[FJCamper]

Our custom tank

Hi VW Jim,

The "ball valve" is a precision plumbing item used to shut off compressed air, water, gas, whatever. They typically have levers on them. The term "ball" refers to a steel ball inside the valve body rotated by the lever to turn the ball so a hole it in allows oil (in this case), to pass.

The other precision valve type is the "needle valve" which allows calibrated amounts of (whatever) to pass. Like the name implies, a tapered needle is inserted in a machined hole by a lever or screw mechanism to control the amount of flow. We use a needle valve in our pump-fed water injection system on our LeMons VW Super Beetle road racer.

We do not use ball valves on our dry-sumpted VW Super Bug or Historic Sportscar Racing Ghia, as we have the oil tanks mounted so low that drain-back is a minor problems. We have a custom-made square tank in the Bug and use a conventional circular tank in the Ghia. Both are 3 gal. capacity.

We do not use sight glasses on either, as they are mounted low behind what was the passenger seat (US left hand driver cars) and the circular tank actually protrudes an inch below the floor pan.

We have a dip stick on the Bug's tank, but have to remove the Ghia's filler cap to insert a dip stick in it. We run each tank at about 90% full to allow for heat expansion of the oil. The oil lever gap in a dry sump is called "head space." You need at least a half-inch inside diameter vent line off the tank to a catch tank so if you overfill, the tank will "burp" and makes it own head space. Very messy.

On our engine test stand, we use an old 5-gal. NASCAR dry sump tank with a ball valve to feed our engines.

Once you get used to dry sumps, you'll never use anything else.

FJC

[twodollardoug]

My 914 is a dry stumped type 4. Like fj said, I love my dry sump system. I give a quick look at the sight tube (I made my own tank) about once a month. My car is my daily driver. I don't run a ball valve. If the car sits for a week, about half of the oil will leak through the oil pump into the sump of the engine. But it's no big deal and I don't even think about it any more. I have let the car sit until the whole sump tank has bleed into the engine. 10 qts. Never a problem it will smoke for a minute after start up but clears up right away. It's not enough to hydrolock. The down fall of my dry sump system design is that it takes a few minutes to get all that oil warmed up.

[vwjim]

Great answers guys. Very grateful.

I'd assumed the ball valve was automatic, hence asking for details. Like a solenoid valve. Though that would be simple to plumb in, it would be very costly if it ever failed... Think a manual one would be safer if I mounted the tank high up, like inside the Bug.

[DORIGTT]

So if it isn't that big of a deal (drain back) why do so many get worked up about it?

My 914 is a dry stumped type 4. Like fj said, I love my dry sump system. I give a quick look at the sight tube (I made my own tank) about once a month. My car is my daily driver. I don't run a ball valve. If the car sits for a week, about half of the oil will leak through the oil pump into the sump of the engine. But it's no big deal and I don't even think about it any more. I have let the car sit until the whole sump tank has bleed into the engine. 10 qts. Never a problem it will smoke for a minute after start up but clears up right away. It's not enough to hydrolock. The down fall of my dry sump system design is that it takes a few minutes to get all that oil warmed up.

[twodollardoug]

Who knows.... Like I said my car is my DD and it's been dry sumped for about 7 years now. I like it so much that I am currently building another one for my 62 bus.

[vwjim]

I GUESS, if you have substantial drain back, you could have the pistons sitting deep in oil? Plus if the tank empties completely, then you won't get any oil pressure to the engine until oil is scavenges out then pumped back again.

[66brm]

That's why the scavenging side of the pump typically has larger gears, to return oil to the tank faster than the engine needs it

[vwjim]

Yep. But there must be a delay IF the tank has drained completely empty?

[FJCamper]

IF THE OIL TANK IS EMPTY ...



If the oil tank is empty, having drained-back into the case, you are going to have a very full case. That might mean hydraulic lock if the cylinders are full.

I have actually seen this situation. It happened to us not because of drainback, but because the oil pickup inside the case had become clogged. We were using an "oil suction kit" as shown, and this, as compared to a standard oil strainer, has considerably less intake area. At Daytona, a
wad of foreign material resembling a well-chewed Brillo pad somehow got stock to the red-anodized oil intake and totally blocked it off.

No oil was being picked up to refill the oil tank, but the pump was still going, and the tank was filling the case. The engine choked and died and by the time the tow truck got our car back to us, there was oil splashing out of the carbs. We found the foreign material when we dropped the oil plate. The material turned out to be the remains of a stainless steel cleaning pad. Had it come from inside the oil tank, a forgotten item in a clean-out attempt?

The pad had been pulled into the engine through the -10AN braided steel OIL IN line. That's suction. Then it had been chewed up by the oil pump gears, and the cam gear, and finally lodged up against the oil suction intake screen. Incredible.

The oil tank was empty. We had to drain the case, get 3-gallons of oil back in the tank, and keep on racing.

In times where we've had a lot of drainback, we estimated how full the case is, and crank the engine over for a minute of so, no ignition. Usually the pump will refill the tank, and we can run the engine normally.

FJC

[andy198712]

the thing that put the nail in the coffin so to speak for my dry sump setup was the cost of the oil.... at about £55 for 5 litres and i'd need two of them every 3k miles..... or do you extend that out with more oil?