Oil consumption - rover k series (R500)

[Colin_T]

What is considered a “normal” amount of oil consumption of a tuned k series with track use? 

 

 

[Gridgway]

can't give a specific number but my SLR used pretty much nothing on the road, but I remember a lot being used on track

[7 wonders of the world]

Are you talking oil being burnt in the chambers or discharged into a catch tank. 

Is your car wet or dry sump

What symptoms are you expiriencing...? 

 

[Colin_T]

Little to nothing in catch tank. No leaks. No excessive smoking out the exhaust. however tops of the pistons do look like they have quite a lot of deposits on top. Plugs are not oily or wet. Engine rebuilt 1000 miles ago. 

dry sumped.

oil level was topped up and level checked accurately before trackday.

used 1.5 litres on the trackday after refilling and accurately checking the ammount required to reach the same level as it was before. 
 

[Gridgway]

I'd say that was what my SLR used to use on a track day.   Nearly caught me out first time as I thought it used nothing!

That was no oil used on the drive to Barcelona, thirsty at the track and nothing on the drive back (to the UK).

[7 wonders of the world]

on the rebuild was it bored with new pistons and rings....

if so how was it bedded in ...

[Colin_T]

New forged pistons, rings, new liners. Also had new valve guides and stem seals. 
(plus rod bolts, springs and caps, all new gaskets / seals, oil pump etc) 

running in oil (unsure which, was in the engine when I collected the car)

instructed by engine builder to avoid high revs or labouring. Normal driving mixed with moderate / mid  throttle pulls for couple hundred miles.

after this oil was dumped into clean bowl and thoroughly inspected - all clean. 

Drained as much oil as I could, oil pipes allowed to drain down, bottom of oil bell tank plate removed, drain in sump removed.
 

Then refilled with fresh oil and filter.
Millers 10/50 CFS NT+

[7 wonders of the world]

so assuming the rings were bedded in correctly, all to often people pootle aorund with new engines.

Is your DS plumbed open or closed...?, if open this gives the scavenge more work as it has to evacuate excess air in the crankcase this carries oil mist which is then dumped in the catch tank.

running closed pulls a partial vacuum and greatly reduces this, the windage is also reduced so there is less volume of air being forced thro the catch tank, hence less oil dumped, the primary reason for running closed is to reduce aeration in the spent oil

 

[Gridgway]

4 minutes ago, 7 wonders of the world said:

so assuming the rings were bedded in correctly, all to often people pootle aorund with new engines.

Is your DS plumbed open or closed...?, if open this gives the scavenge more work as it has to evacuate excess air in the crankcase this carries oil mist which is then dumped in the catch tank.

running closed pulls a partial vacuum and greatly reduces this, the windage is also reduced so there is less volume of air being forced thro the catch tank, hence less oil dumped, the primary reason for running closed is to reduce aeration in the spent oil

 

Not sure the catch tank is an issue as there's nothing in it?

[Englishmaninwales]

16 minutes ago, 7 wonders of the world said:

so assuming the rings were bedded in correctly, all to often people pootle aorund with new engines.

Is your DS plumbed open or closed...?, if open this gives the scavenge more work as it has to evacuate excess air in the crankcase this carries oil mist which is then dumped in the catch tank.

running closed pulls a partial vacuum and greatly reduces this, the windage is also reduced so there is less volume of air being forced thro the catch tank, hence less oil dumped, the primary reason for running closed is to reduce aeration in the spent oil

 

I’m not an automotive engineer and I’m probably wrong, but would a scavenge pump’s efficiency for oil suction for an engine sump that is a partial vacuum be lower than if the sump is at atmospheric pressure ? ( I take your point though for less oil aeration).

[Englishmaninwales]

31 minutes ago, 7 wonders of the world said:

so assuming the rings were bedded in correctly, all to often people pootle aorund with new engines...

 

Agreed, during run in, I was advised to avoid prolonged periods of idle and to do repetitive 3-5k 3rd gear accelerations with WOT to maximise cylinder pressures to bed the rings in.

[7 wonders of the world]

21 minutes ago, Englishmaninwales said:

I’m not an automotive engineer and I’m probably wrong, but would a scavenge pump’s efficiency for oil suction for an engine sump that is a partial vacuum be lower than if the sump is at atmospheric pressure ? ( I take your point though for less oil aeration).

The lower the crank case pressure the easier for oil to return to the trough. Reduced wind age. 

Reducing the air volume increases the pumps efficiency as less of the pumps working volume is occupied by compressed air. 

[SLR No.77]

12 hours ago, 7 wonders of the world said:

Reducing the air volume increases the pumps efficiency as less of the pumps working volume is occupied by compressed air. 

I hear what you’re saying but you’re not convincing me! It’s the pump that produces the lower pressure therefore surely the pump is needing to work harder to suck out air/oil/mist if it’s pulling against a partial self-induced vacuum.

I’ve run sealed, unsealed with a small filter, and my current setup could best be described as semi sealed. Theres the added issue with the K-Series belltank that the capacity is marginal and over-filling by even a small amount will dump oil into the catch tank, for some cars this is a way of finding the right level, for others it’s a continual fight between dumping oil and having enough. A taller tank would be better and much of the standard thinking with dry sump systems could then apply, but the belltank limits the system massively. 

Add to this that measuring the level of frothy oil is hit and miss so there’s a tendency on track to want to add more oil, causing more froth, and so on. I reduced this a little running with a breather on the cam cover (to breath in, not out) but still not completely satisfactory. 

The setup I now run is one that IIRC was an idea of Peter Carmichael’s around 20 years ago which involved bringing together the vents from the belltank tower, catch tank, and cam cover. After trying a few different setups I now have the tower vented to the cam cover, and cam cover vented to catch tank. This setup has given me far more dependable oil levels and consumption has reduced. The caveat here is that don’t vent back to the engine if running AP bearings, my understanding is that the acidic nature of the gasses can damage the bearing material. Mine has standard o/e Rover bearings.

To answer the original question … I believe previous high consumption was a result of too much frothing causing over-filling and more oil dumped into the catch tank, plus on track a tendency to burn a little more as well. I certainly found measuring the level accurately during a track day impossible. Even with general road use the oil level was a complete lottery, the low level telltale being the OP gauge dipping a little under braking. 

Back to my setup, a photograph probably explains it easier. The catch tank is out of view under the airbox and there’s a vent pipe from the catch tank running to the back of the car. I used to have a catch tank on the bulkhead but breathing in vented gasses is not a good idea.

Stu.

[7 wonders of the world]

Understand your bell tank points thankfully I don't run one.. 

Although the pump may be working harder in a sealed set up it is more efficient since it's primary function is to pump oil this is hindered by excess volume of air which is present in open systems. 

Even in a sealed system it does still vent to atmosphere after the catch tank, the intention is only to reduce the free flow of air into the crankcase. 

Worth noting that all DS tanks are not the same this also applies to catch tanks both should be correctly designed, located and plumbed. 

 

[Gridgway]

24 minutes ago, 7 wonders of the world said:

it's primary function is to pump oil this is hindered by excess volume of air which is present in open systems.

I'm still not getting this.  The oil pickup must be substantially below the level of the oil to be pumped.  How does lower air pressure affect this?  Also how much below atmospheric pressure would a sealed crankcase be? 

And is this related to oil usage (burnt) that the OP is asking about?

[Colin_T]

I have breather setup closely matched as possible to how I ran it on my dry sumped 8v Vauxhall race engine.

this ran a single outlet from rocker cover, to top of the oil tank (in this case was a millington style tank, which had an integral separator built into top of the tank) then single outlet to a catch can with breather filter on top. 

the fitting on the rocker cover was drilled and tapped to accommodate carburettor jets so I could experiment with bringing the crankcase pressure down on the rolling road - even rigged up crankcase pressure sensors for this testing.
I have not done such mods to the k series rocker cover yet, but I did inspect how the galleries on the rocker cover work and I use the most rearward one as that was smaller of the two, the other one remains blanked off. I have tried to utilise the filling tower on top of the bell tank as a seperator, kind of like how my millington tank was, so it has an in/out drilled and tapped into it.

so I have single outlet from rocker cover > to top of bell tank tower  > outlet from top of bell tank tower > mocal catch tank with breather/cap. 

crude drawing of my setup below:

I get little to nothing in my catch can, from 2 trackdays and maybe 800 road miles I drained probably less than 100ml of the usual vapour collected watery fuel stinky oil

i get no residue out the actual breather on top of the catch can or anything. 

just trying to work out if the on track oil consumption I’m experiencing is normal for these, my k series experience consists of this one.

other pipe going to catch can comes up from gearbox. 
 

Colin