Dry Sump Tank Size Questions

[Jeremy Soule]

My FST conversion is still wet sump due to size and cost of the tank. I've been a-thinking bout repurposing a medical oxygen tank, 4" diameter and 24" tall approx. Any thoughts ideas on that. Is there an advantage to adding length (2") to the car? Thank. J

[Bill Bonow]

Jeremy,

Lets get you some good information based on what you have to work with.

Looked through the master list and did not see a car for you, so a good start is the make/chassis you are converting. It's possible someone may have built a tank (or two) for that model car. Makes info a lot easier. Many of the guys are on their way to Grattan, but I'd bet there are still plenty reading here who can help.

I've been working on a universal tank for a while with the intension of not lengthening the chassis. It's a tough deal, those 2" sure make life easier in many ways. That said, I have raw extruded aluminum in a 4" round that I'm now focused on for a "simple" tank. Maybe not 100% universal, but I'd bet it should fit a bunch of converted FV models. So, if you're making your own, a 4" dia. X 24" tall should be a great starting point.

Bill

[Jeremy Soule]

Bill thanks for your interest, the manufacture of my car is in question. I am in Arizona and currently the only FST running so did't update the list(May start another thread on that topic).
Here, I hope, is a photo of the engine compartment. There is 6.25" between the large part of the cylinder and the fire wall. I noticed that there is actually more room on the other side of the engine bay due to the asymmetry of the engine by about an inch and a quarter, but the distributer tilts into that space a little.
I am have a slim extended sump that seems to work fine at my newbie speeds, I've run the car once at Indy Motorsports Ranch in southern Az. I modified the kit to lower the pickup some. I noticed that the stock pickup sits quite high due to the factory screen thing. J

[Bill Bonow]

Jeremy,

Dumb question, if still wet sump, where does the oil go in?

The thinnest tank I seen to date was just over 1" thick (Dr Doug Sharp's Jacer), so it's not an impossible task. If you go to a dry sump, no extension will be required, all stock stuff including the original screen.

6" or better will be plenty of room as is. How tall is the firewall/body at that point?

[Garry Sharp]

Here is my Citation tank fitment. Tank is from ARE.

[Brian]

How much oil do you need in your system? 4" diameter ID is 2.45 litres per foot, so your tank will have less than 5 litres capacity total, say 3.5 litres of oil with a decent head space for de-aeration. Is that enough for your engines?

Brian

[Bill Bonow]

Brian,

That is pretty close to the minimum in these engines. We started in 2007 with 8 quart systems and then kept shrinking them down. 4 quarts in the tank (about 3.5 litres) with about 1.5 quarts in the engine, seems to be about as small as you want to go.

[WASP]

Jeramy: You need to have about 41/2 quarts capacity to feed the dry sump system.
make a 4quart mock up out of construction paper and work it in the space you have
available. Cut the mock up in half or what ever you have to do to make it fit. Make
a final mock up and send it to us and we can make a tank for you. Remember that you will have a fitting on the bottom of the tank to plumb the pump. Vent, fill, and oil
temp sender. A baffle is needed inside the tank to remove air bubbles. The lines
required for the system make up the 1/2 quart you need. The tank will be about 2/3
full at full throttle.

[Jeremy Soule]

Yes I was thinking of mocking something up with cardboard.
If a 4" diam. tube was used as a starting point. 4 qt =231 cub. inches. Using the formula for the volume of a cylinder a hight of 18.38" would hold 4 qt. (check my math).

Bill I fill the oil by removing the breather tube fitting, 3/4" brass to 1/2" barbed hose, and using a long funel. The brass barbed fitting is screwed into a 1"-3/4" reducing bushing which is steel and is threaded into the case, fits perfectly with out any drilling I might add. I can add a little oil through the breather tube if needed and shouldn't need to change the oil to often. Would you say that 6 hours of track time with synthetic oil is ok assuming I don't get the oil to much over 240 degrees?

[Bill Bonow]

Jeremy,

You're good on oil life, but the oil adding procedure is a little different

Just remember that a round tank is not mandatory at all. Make what fits your car keeping in mind that "tall and skinny" is preferred.

I've been using a rectangular box (2.5" x 5" x 23") with no baffles for the past 4 or 5 years. I'm happy as a lark with the OP numbers on the DA.

Here is a photo of my tank

[Jeremy Soule]

Very nice installation Bill, I like that it's tucked in in front of the pulley away from the L. side exhaust pipe. Looks like a fabricated steel tank but the cap and filler neck were re-purposed from something else?? Good to know that a circular tank is not necessary.
Noticed you have an extinguisher nozzle pointing at your fule pump, very wise, I'm going to do that! By the way if you don't mind me asking, what is that brass fitting on your fuel line( looks like a schreaider valve).
I am digging your carbon fiber cover plate. J

[Jim Nash]

Just a bit more info I have found about oil tanks. I have tried 2 tanks in my car. The one on the left is the original desgin and the other is one I tried in an effort to make it easier to fit in a conversion. The original is 3.25"x6"x17.5"(.065 wall). The second one is 2"x6"x23.5"(.12 wall). You can work out the volumes.

The original worked great, no problems. The second one was run for a day at MidOhio. I noted some significant drops in oil pressure on the data. I knew the tank was as full as I could run it and decided it simply did not have enough capacity. It could have been something else but I have no interest in doing more testing to figure out what that might have been.

The second one was significantly cheaper to have made as I used 2x4 alm. tube rather than having it bent up out of sheet. I would use this method again if I were to make another tank but with 3x6 rectangular tube. The added weight is not an issue.

I doubt the 3x6 tank will fit your car but hopefully this gives you some food for thought. Maybe you could build a 2x6 tank with a step at the bottom for added capacity.

Jim

[greg V]

I would never use anything but a round tank with baffles. I have seen these square tanks fail as far as really foaming up the oil to where it all ends up in the breather tank.

[dereklola]

How are people using or planning a square/rectangular doing to deaerate the oil?

Obviously one way is to incorporate a cylinder somewhere - on top, inside, or even remote -and use that as a "swirl pot". The other which I learned from my early Lola FF is to feed the returning oil into an internal tube with several small holes mounted near a sidewall - the oil then squirts at an angle against the wall and "squeezes" out the air.

[rgu]

Our two cars have one, a round Pace tank and two, a tall rectangle tank. The Pace has all the desired features but they both are very successful installations. I believe the extra height of the rectangle tank makes up for its lack of features. Used with properly maintained oil level neither has given us any trouble. The key in Formula First is to have at least six quarts of oil in the system. More is fine but unnecessary.

[Jim Nash]

I have put baffles in my tanks to minimize foaming. I doubt they are optimized but I have not had any problems with a lot of oil ending up in the catch tank. I ran a Lola 540 for probably 18 race weekends that had a rectangular tank with no baffles and had no problems. I am sure others have had problems but I can't say that I have.

I have attached a drawing of the tank for the MRC.

Jim

[SamF]

After having two engines expire into a pile of small metal particles into my oil system at the past two races, I would strongly recommend a tank that you can remove the top off of and clean it out at the track. Speedway sells a nice little 16 inch tall 6 inch round tank with a removable top and baffles that to me looks like the near perfect off the shelf item for a FST. They have taller tanks as well if you have room in your engine bay. My tank has a removable cover plate that allowed me to open the tank and completely clean out the chips and other expensive rubble that found their way into the tank, and that was key to getting the engine change done quickly and safely at the track.

[dereklola]

This one? Neat.
How does the top seal - o-ring, gasket, silicone goop?

[SamF]

That is the one.

It has an o-ring under the top I put a very small bit of sealant to just hold it in the groove to make putting the cover on a bit easier. You would need a to put a plug into the lower return port and a step down fitting from pipe thread to -8AN in the upper return port.. The lower port either needs a new nipple welded on or an adapter fitting they sell to step it down to a -8AN.

Two open ports in the cover are used for the engine sump vent and to the puke tank.

The one modification needed is a 1/8 inch pipe thread port welded on to put an oil temp sender in, if you are not putting the oil temp sender someplace else.

i would use the tallest tank that you can fit in you engine bay for max oil and venting capability.

[Jeremy Soule]

I think true foaming, as in the oil becomes wipped up with teeny bubbles like whipping cream is caused by something else besides the shape of the tank. I've heard it takes a long time(days?) for this foam to dissipate. Aeration I would think would dissipate quickly as soon as the engine was shut off. I have never witnessed either case. I did read an interesting article by Smoky Yunik where he built an oil pan with a sight glass and used a strobe light to watch oil behavior in the pan.
Sometimes I think that in a round tank where the oil is fed in tangentially and the outlet was set in the middle of the bottom would cause a whirlpool effect like a bathtub drain and introduce air to the outlet but the hight of the tank, volume of oil, would probably cancel that out.
Any thoughts or actual experience??

[dereklola]

- - - - Aeration I would think would dissipate quickly as soon as the engine was shut off.
Sometimes I think that in a round tank where the oil is fed in tangentially and the outlet was set in the middle of the bottom would cause a whirlpool effect like a bathtub drain and introduce air to the outlet but the height of the tank, volume of oil, would probably cancel that out.

I'm no expert but that's my understanding as well. The height of stored oil in the tank, while running, is probably the clue to avoiding the bathtub drain effect.

On a practical level I've had experience of three oil tank designs - the Lola I described above (small holes squirting oil/air at an angle against a wall) - a Ralt with an 8" diameter and not-very-high tank with nothing but a tangential return pipe on the 8" inside diameter - and a March which is mostly rectangular but has a 2-2.5" diameter double cylindrical extension on top which I haven't yet figured out! I think the space between the two cylinders is for the oil to swirl and the inner cylinder is for air to escape ( and for fill oil to enter).

All three tanks above were smaller and /or conical at the bottom than the top and the internal feed pipe for the outlet just had a wide slot at the very bottom about 1/4" from the very base of the tank (to make sure that only oil was sucked even under high G loads.

Laugh - I bought a beaten up Ralt tank to cut open to see what was inside - and found nothing!

I think the bottom line is - if it works it's fine - and Sam's tanks apparently work.

[Bill Bonow]

Looks like a fabricated steel tank but the cap and filler neck were re-purposed from something else??

Nope, aluminum with rattle can black. No real reason for the paint, just thought it would look different

Good to know that a circular tank is not necessary.

If you look around, round tanks are not all that common in formula cars. Typically due to the "no room" factor.

By the way if you don't mind me asking, what is that brass fitting on your fuel line( looks like a schreaider valve).

That is the SCCA required fuel testing port. And for what it is worth, I've had it installed for 7 years (when the car was built) and NEVER used it.

I am digging your carbon fiber cover plate. J

Had to have something "high tech" on the car