Sump + Cooler

[deezee]

I've chopped up a sump off a Sierra DOHC to suit my 16V RS 2000 engine. Now cos its aluminium I tried to keep the cut as simple as possible to make the welding back up easier. So effectively I've just taken out 30mm from the sump.

Now my plan was to add back this stolen capacity by fitting an oil cooler, however my buddy tells me this is a daft idea. He believes that that the sump needs its original capacity to avoid starvation? Surely as long as there is plenty of oil in the system, its all that matters?

Could you guys shed some light on this?

[HandyAndy]

i personally would agree with your buddy on this one, sorry if thats not what you want to hear

but with the correct oil capacity actually in the sump you get a "splashing effect" over the main big end bearings which aids the lubrication & cooling effect needed for that area.

cheers
andy

[deezee]

I was under the impression that splashing is the worst thing ever for an engine. Thats why people put extra baffles, or like Caterham, fit sponge, into the sump. Otherwise splashing adds air to the oil and massivly reduces its ability to lubricate your engine Otherwise when you dry sump the engine you'd wreck it, if you needed splashing.

Cooling isn't an issue if you have fitted an oil cooler

[spud69]

The oil level should be set to the original max level on the dip stick, the level is set just below the crank so that frothing of the oil does not occur which will detract from its performance. The most importance thing is if you have chopped the sump is to try and retain oil capacity by lengthening the sump and baffle it, making sure the pick up is close to the bottom of the sump.
If you add a cooler you will need to add extra oil for the cooler and pipe capacity but still fill to the max level on the dipstick.
The most important thing from my experience is to fit a good oil pressure gauge so that you can be sure the oil feed is running properly.

Regards....AndyH

[Bonzo]

Here's my thoughts on the subject

Not being able to remember the shape of the Sierra DOC sump it is difficult to estimate the reduced volume of oil ( Photo would help )

If I take the 25mm reduced from my CVH sump as an example.

My logic is this.

Not actually reduced the sump oil level, just the depth of oil & the amount available.
In my case I have extended the deeper part of the sump forward to regain some of the lost capacity.

Dipsticks are marked with a max & min level, usualy about 20mm apart.

The engine manufacturer would have set the minimum oil level at a very safe margin to warrant that the engine will continue to perform in all conditions.

Most cars that have come to me with the customer saying " when cornering the oil light comes on " .
When the oil level is checked it is barely visible on the dipstick.

In an ideal world the solution would be to extend the sump a little to make up for lost capacity.

Provided the sump is well baffleld & there is enough oil available to the oil pump in all conditions an oil cooler may be of some benefit in so much as it will cool the reduced volume of oil available.

Lubrication of the main & big end bearings is provided via the crankshaft. The crankshaft is drilled at each journal, oil is fed direct from the oil pump, through the crankshaft & onto the bearings providing lubrication.

This is why it is possible to use a dry sump set up.

Early in the morning, so hope it make some sense

[deezee]

I'm still a little confused. I appreciate that the oil needs to clear the crank to avoid frothing of the oil, I also realise that my dipstick is now useless as the sump is 30mm lower and the dipstick strikes the sump before its seated. So the most I can fill the sump is to below the crank / crank baffle.

My concern is that under cornering the shallower oil level may expose the oil pick up. No amount of wings or extensions are going to be able to raise this oil level. However I think making a new baffle for the sump might help reduce any surge in the sump.

[HandyAndy]

sorry Deezee, duff info from me this time,

yes you are correct, air in the oil making it froth is not good, tho i didn,t mean it to that degree,

my own sump has been chopped but extended to still allow the correct qty of oil tho the level is not the same as original sump due to the "floor" of the sump being raised up,

sometimes the brain gets all befuddled

cheers
andy

[flyerncle]

Adding wings to the sides is the best option to increase the capacity not the oil level. You will need baffle's to stop surge and therefore loss of oil pressure which is the last thing you want. Fitting an oil cooler will have the effect of adding slightly more capacity and cool the oil but make sure you fit a thermostat to it as well ,low oil temp is as bad as too high a temperature.
Main thing is to make sure the pick up will always be covered in oil no matter what !s


Follow Spud,s advice and fit a guage and a large warning light.

[car.mad]

i would agree with 'flyerncle' although if you can you need to keep the oil capacity the same as it was originaly

we just finished doing lubrication systems at college, some oil does need to be 'splash fed' up the cylinder walls to lubricate and cool them (oil provides up to 40% of the engine cooling) with a 'dry sump' system this is usualy sprayed up the cylinder walls.

but also be sure the strainer is always submerged in the oil so that there is a constant feed of pressurised oil to wherever it needs to be.

i would say and dont hold me to this bit that too much 'splash' is bad but not enough is bad aswell.

hope this helps a lil bit

Jake

[snapper]

The dip stick top level is the maximum safe fill for your sump, this level stays whatever you do with the sump because the top level is relative to the engine block/crank position.
Cutting the bottom off the sump does not change the fill level it just reduces the volume.
Adding an oil cooler will increase the amount of oil in the system but will not make anymore oil available to the pickup pipe.
Calculating the "Lost volume" is easy measure the square of the sump in mm you have removed, multiply by the depth in mm you have reduced the height/depth of the sump by, i.e 150mm x 150mm x 30mm divide by 1000 = 675 mm or 2/3 of a litre.
The usual diference between Min and Max on a dipstick is about 1 litre so you will now be on near minimum when indicating full, with the extra volume of an oil cooler no problem.
However less oil in the sump means more chance of uncovering the pickup when cornering hard.
Simple solution is a horizontal sump oil level baffle which sits just above the top oil level like a lid limiting the oil from climing up the sides of the sump, a bit more baffling can be welded verticle baffles and the best type of baffle before going dry sump is the horizontal baffle with verticle box that has 4 doors that only open inwards, these are firmly closed by the oil when it tries to excape under centrifugal force but allow oil to flow in easily