15 replies to this topic

[Supercar]

I have a question about a dry sump system. Hopefully someone here has experience working with or designing them.

The engine is a 3.0L V6 twin turbo with rod and piston squirters. I chose an external dry sump pump that is made for a small block Chevy and is capable of pumping about 12 gallons/min at 2500rpm of the pump. It is geared down at 67% the crank speed. I performed a scientific experiment, measured the flow, and it turned out that this pump will flow 25% more oil than the old stock pump. Hopefully this gives you some idea of the oil flow requirements.

What alerts me is a huge discrepancy in the oil line sizes. The stock oil cooler lines are only about 8mm (0.315") on the ID, but most of the new pump fittings are AN12 (15mm or 0.591" ID). The single scavenge-out fitting is a huge AN16 (21mm or 0.827" ID) !!! That's a HUGE and heavy AN16 hose to run to the trunk, where I am planning to install the oil tank! That and the oil tank return line will store about 1.8 liters of oil (1.8 quarts).

Do these line sizes sound normal? If someone knows of a methodology how to properly size these lines I am all ears! Thank you in advance.

[McGuire]

-10 scavenge and -12 pressure, max. Larger can cause aeration problems. At one time it was popular to run one large (like -16) hose on the main scavenge inlet (sump to pump) but multiple smaller lines are better. Most tanks come with -10 or -12 female fittings.

I don't care so much for braided hose in long free lengths. It cannot support its own weight so it needs lots of Adel clamps to be straight and nice and keep out of harm's way. Plus it can't handle much bend radius, it's bulky and heavy and costs like ten bucks a foot.

Hard line will look and work nicer esp. if you fab up some nice little bulkhead plates for both ends. Naturally you will want enough hose at each end to allow flex and to hang without strain. It is best to think of braided hose as flexible, not bendable. If you need a 45 degree turn do it with the fitting, not the hose. Also you will need a shut valve or when the car sits for a few days you may find the tank dry and three gal. of oil in the oil pan.

Also, this sounds stupid but good practice is to plan out all the plumbing systems on the car so it is impossible to hook up the lines wrong -- they will only reach and fit one place each. It will just come out looking cleaner and more orderly that way, and will save you time answering a hundred questions from part-time helpers about wheredoesthisgo. Wiring too.

[bobqzzi]

I agree with McGuire, and would add that I find Aeroquip socketless hose much easier to deal with than braided stainless. It is much ligher, more flexible, cheaper, easier to use, and doesn't try to saw a hole through everything it touchs. It is certainly up to the job of an automotive oiling system. Assembly is much easier and eliminates the common novice mistake of misassembling the ends.

I normally size lines as follows:

(2) -10 scavenge lines from pan to pump
(1) -12 scavenge line out to tank
(1) -12 pressure from tank to pump
(1) -10 pressure from pump to engine inlet


McGuire, what are your thoughts on oil cooler placement? In the pressure side or scavenge return?

[Greg Locock]

Wiring too

The HUD (instrument pack) in the Esprit used to have two identical D plugs, one to go in the left, one in the right.

Problem on the assembly line with a no-start, some guy had pulled enough slack to plug the wrong one in the wrong side of the HUD, and the other in the other side.

So they made a harness change, switched to male plug on one side, female on the other.

Problem on the assembly line with a no-start, some guy had plugged the two body side plugs together, male to female.

I think we got it right third time lucky.

[Supercar]

Thank you all!

I looked into the stock pump and most of the channels there are 15 mm in diameter, which is more like -12. I think I will go mostly with -12 fittings then, and then probably -10 for the scavenge inlets.

Thanks for the tip about watching the oil level, McGuire. I would have never thunk about this. I will keep an eye on the dry sump tank, it has a transparent sight tube on the outside. If the oil level goes low after sitting for a while I will have to start worrying.

I am now thinking that perhaps I should go ahead and buy a 4-stage pump with 3 scavenge sections. It will work much better on a V6 that has a shallow oil pan. I originally bought a 3-stage pump with only 2 scavenge sections because I thought I would keep the deep stock pan and install the pump somewhere on the side. I ended up shoving the pump right under the engine. Now I want to collect all that oil from the individual crank sections right away and not wait for it to flow to the far corners of the pan.

That Aeroquip socketless hose looks like a the best hose to use for the individual scavenge sections. I can weld those barbed nipples right onto the oil pan! Thanks, bobqzzi. I am a little bit worried about using it for other hoses because there may be some pressure and vacuum spikes that will exceed its ratings of 250 psi / 18 in Hg if I start the car in winter. Can I trust this hose for winter starts?

The oil cooler location is a great question. I have seen both schematics. Let's see:

A) Keeping the oil cooler after the pressure pump and filter:
- Hotter oil in the oil tank, better deaeration
- Hotter oil in most of the system, smaller pumping losses
- No air in the oil cooler
- Oil temperature control (thermostat) right before the engine; most stable oil temperature; quicker system warmup.
- Minimal modifications to the current system

B) Moving the oil cooler after the scavenge-out:
- Hotter oil in the oil cooler, more efficient to cool, if the oil cooler can be kept mostly air-free.
- More constant temperature in the oil tank

I think the winner is A. Mainly because B does not control the oil temperature well. Plan B controls the oil temperature coming out of the engine, regardless of the oil temperature in the oil tank and in the test of the system.

Thanks for the layout and wiring tips too. If the system works I will people wanting to buy it, and I do not want to troubleshoot their installation if they decide to the filter the aerated oil and then dump it back into the oil pan!

[Fat Boy]

Put the cooler after the filter. That way if you lose an engine you'll have less crap to clean out of the cooler.

As far as lines, fitting, etc., I prefer to use XRP stuff. I think they're about the best stuff out there right now.

[Supercar]

Well, since we have touched upon the less glamorous and more practical subject. Should scavenge inlet filters be used? Is there still a contravercy on this subject, or is there a consensus now? Would some wire windage tray be sufficient to catch the big chunks that the pump would otherwise choke on?

The pump is relatively cheap and rebuildable, so I am mostly worried about seizing the whole pump here and oil-starving the engine, rather than putting a few scratches on the inside of it.

[AndrewD]

While we are on the subject of dry sump systems, sorry to hijac your thread,

Does anyone know of any good literature out there on these systems. i.e. research papers on the net?

In particular the design of the tank and the dearation system?

[vvillium3]

yes, agreed. Any suggestions on design lit???

[bobdar]

I would definitely recommend a scavenge screen in the pan, but haven't any experience with scavenge filters. About the most common oiling system failure in our formula fords is jamming the scavenge rotor with a chunk of something, usually timing chain roller bits, which could be prevented by a good screen.

[bobqzzi]

Originally posted by Supercar
Well, since we have touched upon the less glamorous and more practical subject. Should scavenge inlet filters be used? Is there still a contravercy on this subject, or is there a consensus now? Would some wire windage tray be sufficient to catch the big chunks that the pump would otherwise choke on?

The pump is relatively cheap and rebuildable, so I am mostly worried about seizing the whole pump here and oil-starving the engine, rather than putting a few scratches on the inside of it.

I prefer to use in pan screw-in filters. A number of places sell them.

The socketless hose is up to the task of cold starts.

To me, when and engine blows, it means the oil cooler goes in the trash. I don;t know how you would actually clean one so you trusted it.

[McGuire]

I want a full-flow filter in the pressure line before the cooler. (Many setups like the original Cosworth DFX had the filter mount built right onto the back of the pressure pump.) So it's pump, then (centrifuge if equipped) then filter, cooler, engine supply. This puts the cleanest, coolest, least aerated oil in the system into the engine as I see it.

If space and weight are not an issue I also want an Oberg or similar inspection screen "filter" in the scavenge line. (I believe it also provides some defoaming.) Then, because I am Mr. Anal, I watch both filters like a hawk. I adore those nifty spin-on oil filter cutters that came some along a few years back. When it came out people who know me sent them to me from all over. Look, it's McG's dream tool. I still have a half-dozen of them I think.

I don't want any of those little finger screens anywhere in the lines. Near as I can tell they merely ensure that the oil supply will be totally interrupted if something does go wrong.

[McGuire]

Originally posted by AndrewD
While we are on the subject of dry sump systems, sorry to hijac your thread,

Does anyone know of any good literature out there on these systems. i.e. research papers on the net?

In particular the design of the tank and the dearation system?

There are a zillion SAE and NACA papers, and magazine articles cribbed from them. Also, many of the dry-sump mfg'ers supply manuals and technical support.

[McGuire]

Originally posted by Supercar
Thank you all!

Thanks for the tip about watching the oil level, McGuire. I would have never thunk about this. I will keep an eye on the dry sump tank, it has a transparent sight tube on the outside. If the oil level goes low after sitting for a while I will have to start worrying.

This usually won't happen right away. When the pump is brand new it will be tight enough to hold oil against gravity. (The tank will invariably be higher than the pump.) Then when it gets a little wear on it, the pump will let the oil drain back through. You can fix this by a) draining the oil out of the tank between events, which is good practice anyway, or b) installing a shut valve or check valve in the line.

[Supercar]

Bobqzzi, couild you send me a link to at least one of those pan screw-in filters? Google can't find any "pan screw-in filters".

Many thanks for that tip about the socketless hose. I dreaded cutting and assembling those AN fittings and paying $30-50 for each of them.

McGuire, do you install a single Oberg inspection screen filter after the scavenge pumps and before the oil tank? I hope you are not that Mr. Anal who would install one of those square CNC machined billet blocks before each scavenge section inlet? Would you think that a good wire mesh in the oil tank would do the same thing?

Philip

[bobqzzi]

Originally posted by Supercar
Bobqzzi, couild you send me a link to at least one of those pan screw-in filters? Google can't find any "pan screw-in filters".



Philip

http://www.drysump.com/screenfit.htm