Dry sump system capacity .....

[SLR No.77]

My K-Series car is running the Caterham belltank d/s system ...... but I'd like to increase the "effective" oil capacity somewhat (currently IIRC it's approx 4.5L). Would adding the R500 short Apollo tank help with capacity (this one) or does it just increase the total without changing the "effective" capacity, ie. will there still be the same issue with the small margin that exists between blowing excess oil from the top of the tower into a catch tank, and starvation at the belltank exit particlularly under heavy braking? I realise the theoretically correct answer would be to have a much taller tank but this doesn't seem feasible if retaining the belltank/tower setup.

 

.... Or is there a way of increasing the belltank oil level without it blowing out?

 

Stu.

[guilleracing]

Hi Stu,

 

If I could offer some of my experience I could save you some money and grief at the same time.

 

This summer, we were developing a bike engined prototype sports racing car. Using a standard design tank, the 14,000 rpm engine threw all the oil out through the breather system into the catch tank. This was at a rate of one litre per mile! It was due to the incorrect design of the de-airation system. We had a number of tanks manufactured before finding the right solution. Eventually through a contact in an F1 design office we found that you need a tank with very tall de-airation tower. This can be made inside the actual tank to keep the overall low but it is the only way to keep the oil in the tank. More oil is not what is needed to prevent the loss of capacity but a better designed system. We discovered this after having five tanks made up!

 

I hope this helps.

 

Greg.

[Paul McKenzie]

Stu,

 

Why do you want to increase oil capacity? I have the same DS belltank set-up on my VX and I've never experienced or heard of any lubrication problems related to the oil volume. However if you've got an oil temperature issue, then the answer is obviously to fit an oil cooler and thermostat. I did this thinking it might be necessary on my engine....however I should have listened to Arnie 😳 as it led to over cooling even on track. I've now removed the cooler and once I've reassured myself after a couple of early summer trackdays, then the whole gubbins will be on sale 😳

 

Paul

 

Edited to say just reread your post and you say you are getting oil starvation...how is this evidenced, on the OP gauge or a low pressure warning light? Can see why you're concerned if that's whats happening!

 

Edited by - Paul McKenzie on 19 Dec 2010 10:18:52

 

Edited by - Paul McKenzie on 19 Dec 2010 10:19:45

[Englishmaninwales]

Paul

The k series retains a large quantity of oil in the engine, partly due to the capacity of the scavenge pump compared to the pressure pump and partly due to its design, compounded by a single sump pick up at the rear. That 4.5 l belltank capacity then gets low under some circumstances. eg under heavy braking

 

Malcolm

[Richard Price]

Stu,

Would adding the R500 short Apollo tank help with capacity

 

It's capacity in the tank that you're needing, not in the pipes (which is effectively what the anti cav tank is)

 

partly due to the capacity of the scavenge pump compared to the pressure pump

Wasn't that the purple pump that was a little marginal with bigger engines, and the gold pump has a greater capacity to cure that?

 

I'd say that either you change to an external, larger DS tank (where its less critical if you run a little short), or you become fanatical about checking the oil level whenever the car is used on track.

 

[guilleracing]

Hello again,

 

I have re-read this and feel that some clarification is needed to understand my answer.

 

A dry sump scavange pump recovers oil from the sump pan at the bottom of the engine. This we all know.

 

What is not always understood is the condition of the oil being scavanged. It has run under pressure through the engine and been whipped into a froth by the effects of being sprayed through the small orifices in the various sections of the engine.. If that wasn't bad enough, the scavange pump draws the oil out of the sump pan was copious amounts of air. The intake of air happens as a result of the oil level dropping during acceleration and cornering and simple low levels of oil. What you end up with is an oily emulsion of oil and air. With the added air, the volume of this mixture is increased a great deal more than the original oil level and this is why is gets blown out of the top of the dry sump reservoir tank ( In your case the bellhousing oil tank.) and you end up with problems related to low oil levels. The answer to this, (If this is your problem) is to have as many oil pick ups in the sump as is practical, at least two. (Front and rear.) and to have a proper de-airation system in operation. Incidentally current formula one dry sump systems employ centrifuges that expose the frothy oil to 2500g to remove the air. I know for a fact that they still suffer from momentary oil starvation problems even with this system.

 

I hope this reads correctly and the explanation is clear.

 

Edited by - guilleracing on 19 Dec 2010 16:25:47

[Jason Plato]

why the assumption that the belltank is too small ?

 

there is no problem to be cured *confused*fill it to 10.75" and not less than 9"

 

unless your engine uses masses of oil 🤔 and you cant complete a race or session ...

 

here is my Duratec R .... C7 TOP

Taffia joint AO with Al

 

[guilleracing]

A little caution on overfilling the tank may be prudent.

 

As indicated in my previous post, the frothy oil does take up more volume than clean pure oil.

 

You may end up with an over flow problem if you do this.

[Englishmaninwales]

Richard

purple pump.......gold pump has a greater capacity to cure that?

Indeed, but I understood from DA that whilst the gold pump was better, but still is somewhat suspect in capacity, but I'm no expert on this!!...

[SLR No.77]

Okay, so the current setup probably suffers in that the volume differential between over-filling and starvation, may in some cases not be enough to allow for frothing, and would benefit from better de-aeration, ie. an improved tower design or maybe the addition of the small Apollo?

I first noticed the starvation at the new Anglesey circuit - heading down from Church it's fast and long up to 6th gear, followed by "long" and heavy braking into a sharp 2nd gear left hander at Rocket - oil starvation everytime! During heavy braking no oil will be scavenged due to the pickup design of the sump.

 

Dave you mention a 1.75" differential from min to max - is this enough to cope with variation in the amount held in the engine and the lack of scavenging under an extended braking time?

 

Also ........ is an external tank a much better option?

I've considered fitting a tank in place of the extended passenger footwell area, although if loosing some length I'd ideally like to retain at least the slope at the bottom of the footwell rather than just swapping for the flat plate .... maybe a "mini" footwell extension! Are the Pace Easy Clean tanks generally though to be the best? What size?

 

Stu.

[Jason Plato]

is this enough to cope with variation in the amount held in the engine and the lack of scavenging under an extended braking time?

 

---

 

yes

 

100's of other caterhams with this instalation cant be wrong - its proven beyond doubt.

 

I imagine you are checking the level incorrectly or your scavenge pump is worn out.

 

placing another tank in that still holds 5 l wont change a thing...

 

here is my Duratec R .... C7 TOP

Taffia joint AO with Al

 

[guilleracing]

Hi Stu,

 

This is possibly not a complete answer but will give you some things to consider.

 

My information is based on a long period of research to cure this problem with a racing sports prototype car. This resulted in a system that managed to keep a full house, 13,000 rpm K8 GSXR 1000 side-car type engine alive in high G turns without loosing one speck of oil. It was also done with 4 litres of oil with no loss of oil pressure. I am confident that the oil was completely pure when being fed back to the engine. (35 psi oil warning lamp.)

 

A lot of racing car type cylindrical tanks on the market do not have a centrifuge fitted in the tank to return the frothy oil back to a pure oil state. They merely send the oil at the point of entry into the tank round the wall of the tank in the hope that this will do the job.

 

They also look nice on the outside but do not have proper baffles inside to slowly allow the de-airated oil to drip down to the bottom of the tank.

 

A tall, small diameter tank will concentrate the oil near the bottom more than a short fat tank.

 

Too much oil is heavy, will cost money, will take a long time to warm up and finally takes up space.

 

Given all the above I would have the following.

 

The tallest cylinder shaped oil tank that will fit under the bonnet. ( Infront of the passenger footwell.) This, to have with a proper centrifuge. The installation of the tank as close to the supply oil pump that you can.

 

(I have a Formula Vauxhall Junior in the workshop at the moment. This will experience more G than a Caterham but the engine revs are similar, the dry sump tank is 27 inches tall and 4 inches in diameter.)

 

 

I hope this is of some use to you.

 

Greg.

[SLR No.77]

I think for now I'm going to work on DJ's advice and play with the level a little . My d/s tank has the Caterham dip stick fitted which obviously measures downwards from the top of the tower, but may not be helping - Dave, are the measurements you mention with the standard blue bottom plate, or using the drain plate we worked on?

 

Stu.

[Jason Plato]

based on std blue plate.

 

I cant recall by how much the modified plate recess's into the tank .

 

dj

 

here is my Duratec R .... C7 TOP

Taffia joint AO with Al