K-Series - Oil surge

[Graham King]

Folks, I know there have been a lot of posts on this subject before, I've even contributed to some of them, but having done the club trackday at Brands last week I am after a better understanding of what is occuring as it doesn't make sense to me. This also happens on the road so it's not just a track only issue.

 

I am running a 1.8K, EU2, DVA modified to 210BHP, with forged pistons, wet sump (all DVA mods to gasket etc, no foam) and apollo. I know a Dry Sump is the real answer but a) that's an expensive option for the small number of trackdays I do and b) there is no realistic offering on the market now. So I'm stuck with making the best of what I have.

 

Symptoms: been discussed by others before, on right handers the oil pressure drops away markedly (down to 15 - 20 psi), depending on temps.

 

I always understood that popular opinion was that this was due to the fact that oil surge moved the oil away from the pickup, but the oil pickup is on the left hand side of the engine (from in the car) so on right handers it should be better than on left handers but the opposite is true as on left hand bends there's little if any change in oil pressure. I used to run with a Hellier baffle to try and combat this behaviour but it made no discernable difference so I removed it at the last oil change.

 

At Brands, my brother was also there in his car, which to all intents and purposes is a similar spec (EU3 not 2) but he also runs a Laminova to control oil temps, on reviewing video footage afterwards, on his car the oil pressure hardly fluctuates whereas on mine it's all over the place. Obviously as my oil temp climbs the surge and change in pressure becomes more exaggerated but even when we are showing similar temp on the gauge the difference in behaviour is marked.

 

Can anyone explain what is actually going on, or have any theories? Is it possible that the Laminova is having an impact (other than temp)? I may well go down the laminova route anyway to control temp but I would love to know how to address the issue properly or at least understand properly what is going on.

 

Apologies for the long post and appreciate anyone with a better understanding than I obviously have.

 

Thanks.

 

Graham.

 

 

[AndrewGP]

Graham, I take you're both running mech oil pressure gauges so comparing like for like? Also I found that the oil level made quite a difference to the amount the oil pressure dropped. Perhaps worth checking your oil levels are identical and retesting to see if the luminova is making a difference.

 

In the end, because I'd spent a lot of money getting my engine rebuilt and also because I was fed up of seeing it drop on the road (I've not done any track days since the engine was worked on) I bit the bullet and bought one of the last of the CC K Series dry sump kits. Yes it was expensive but I view it as an investment and now I get more enjoyment out of the car not worrying about right hand corners. FYI, CC do have several kits still in stock as I've only just done my car.

 

Appreciate that probably isn't the answer you wanted though

[oldbutnotslow]

Hi Graham,

I too would be concerned.

I run a 1.6K wet sump with Hellier EU3, modified 190BHP, with forged pistons, wet sump and an Apollo but no sump gasket (I use an anaerobic sealant in stead), so not all that dissimilar. Also no laminova.

 

I run an SPA digital gauge Pressure and temp here so i am confident about the readings. I have a big LED set at 25psi as a warning and 110⁰c temp warning.I use Fuchs 5-40 titan race oil. My car is track only so lives between 5 and 8k I regularly get 100+ degrees oil temp but a rock solid 80 degrees water temp. My son and I share driving so on an average TD we will cover 200 to 240 miles depending, I run slicks and have never had the warning light on even in 35 degrees ambient at le Mans Bugatti track. At Idle I may get 30 psi after ragging the ar$e off it. I also use a higher capacity oil filter

 

OK some basics and do forgive me if I start with the simple things first most of which I am sure that you will have already considered.

What type of oil are you using? Its more expensive but an Ester based oil is worth it in my view.

How full are you running it?

The pressure senders and gauges are notoriously unreliable. Are you sure that what you are seeing is actually what you are getting?

Has the oil pump had the oil ways fettled to allow better flow? The standard Rover oil pump is not the best so if not or if its well used it may be worth considering a look in this direction.

I take it that you have modified the strainer to allow better oil pick up.

Has the oil pick up still got the small rubber O ring fitted where it fits into the block?

 

As I say you may already have looked at this.

[Mankee]

Grant, can you post up the part number of the oil filter you use, please. Also, does omitting the sump gasket have any other effects, if the "shelf" isn't there any more?

[Titanium7]

Like Grenpayne my engine, wet sump with Apollo suffered the same starvation on RH bends and did damage to the bearings. I also have decided to DS the engine after spending so much on taking it to above 200bhp I don't want another rebuild.

 

Using a CC DS sump, gold pump and Brise Kidney tank. Sourced all but the pump second hand from Blatchat.

[oldbutnotslow]

Hi Mankee

I will consult my book of part numbers and advise

 

I haven't noticed any effects regarding omitting the bump gasket. I don't have any empirical evidence but no shelf should mean that flow of oil as it drains back into the sump is not interrupted.

I take the sump off at the beginning of each year and have the ribs re-welded as sacrificial alloy as the sump gets worn as we hit the kerbs on track during the year. The cost of keep replacing new gaskets was ridiculous ( In know that they can be cleaned and reused but only a certain number of times)

[Mankee]

Cheers, Grant.

 

What's the "shelf" of the gasket actually for? I have a link bookmarked from the archives about gasket removal, but not attempted it myself: here.

 

When I took the sump off my previous engine, the gasket had been kind of "modified" around the oil pickup, in that the shelf was folded up around it. Never really understood why it was done, but that engine never suffered from low oil pressure. Then again, I didn't push that engine or the car anywhere near what I do now...

[Graham King]

Sorry folks have been on train back from work, to deal with the queries;

 

Grenpayne, we are both running mechanical gauges so pretty confident in the readings, oil level on both was correct, according to the dipsticks of course. I wasn't actually aware that Caterham had the Dry Sump kits back in, I assumed they were permanently out of stock but I'll have another look.

 

Grant, we are both using Halfords 0-50 Track Day oil and as said both using mechanical gauges, I tend to run at or just over the level on the dipstick. I'm pretty sure that Oily modified the oil pump when he built the engine for me, how worn it is I don't know to be honest but the engine was 2nd hand when I got it, I then had the bottom end rebuilt but pretty sure the oil pump was retained so that's a possibility. I've not heard of a modified strainer, what does that involve? Can confirm the O-ring is fine as I checked that.

 

My OP at idle after a track session is approx 20, it does come back up after cooling so never been too worried about it but would be interested in the larger capacity filter.

 

What I struggle with is why right handers cause the issue when the pickup is on that side of the engine and why two similar engines behave so differently.

 

Thanks for the responses so far.

 

Graham.

[Graham King]

Mankee, interesting link, I'd not seen that one before. I've just recently fitted a new gasket whilst trying to fix a persistent weep from the sump and did consider cutting the whole "ledge" off the gasket but instead went for 5 holes, it's made no discernible difference. I've only found the North/South issue that PC refers to when the oil level gets a bit too low then it is noticeable under heavy acceleration.

 

The thread does sort of explain why right hand bends may be an issue in that it implies the oil may go beyond the pickup. But why this is more of an issue than left hand bends when the oil surges completely away from the pickup is still not clear. Would the angle of the engine have anything to do with it, although I would have thought that the cornering forces were sufficient to overcome the slight angle the engine is canted at.

 

Interesting stuff though, still interested in any other views.

[Mankee]

I posted a thread about this before, but with a genuine MG Rover oil filter, I got surge on left-handers and solid pressure on right-handers. But with a Halfords filter, I got surge on right-handers and solid pressure on left-handers! How random. *shrugs shoulders*

[SLR No.77]

Quoting Graham King: 

What I struggle with is why right handers cause the issue when the pickup is on that side of the engine

It's because in the Caterham install the engine is tilted slightly to the left side of the car resulting in the majority of the oil returning from the head doing so down the left side of the engine. When you corner hard to the right the oil is held against the left side inside wall of the block and just stops returning soon after which you see the starvation issue. The holes in the gasket help but getting oil back to the sump is simply a fight between gravity and the cornering force pushing the oil back. This is why the Hellier baffle sometimes works, sometimes doesn't, there's more than one issue.

 

You really need to get your head round what's happening in the engine and it all centres around the sump not being deep enough. The reason why (on the K) the oil is checked immediately after the engine is stopped is that the sump level needs to be checked after oil has been removed from the sump and is sloshing around the rest of the system, in the head etc. However the amount that is retained varies dependent upon driving conditions, the more you thrash it on track the more there'll be at the top .... oil pump feed up, gravity return down. Run sustained average higher revs and you increase the up, corner hard you reduce the down. Then as you suffer starvation you get more foaming of the oil further exasperating the problem. It also varies somewhat from engine to engine.

A deep Rover sump will allow for the different conditions needed ... the Caterham sump will not and simply runs out when the conditions dictate. You can baffle all you like but if there's nothing there, your issue will not be oil moving across the sump ... it's just not got back to the sump yet. Straight track, reduce the revs, and the oil has a fighting chance to start to fill the sump again.

 

I had some success in reducing starvation by reducing the spring pressure in the pressure relief valve in the side of the oil pump. This causes the engine to run at a slightly lower oil pressure but also allows a little more oil to be retained in the sump where it's needed to supply the bearings. The spring length can be reduced, if your pressure gets too low just pop a small washer between the spring and the big retaining screw.

 

I also found Mobil 1 to be less prone to surge and foaming than the others (including the Halfords/Caterham/Comma oil) which could just be an ability to return to the sump better, hard to say.

 

Stu.

 

Edited by - sforshaw on 9 Jun 2014 21:15:34

[David Lynch]

Interesting Reading Stu

With Mechanical gauge I've noticed drop off is very level dependent. With the (now removed) sponge fitted I had less drop off but suppose oil will flow faster around it rather than through it with the return flow compromised. I might be the only person in the world considering putting it back in 😬

[CharlesElliott]

I think you need some proper data 😬

 

Try my thread here.

[myothercarsa2cv]

I am now convinced I need a dry sump, thanks all

[SLR No.77]

Fantastic data Charles It really highlights just how much of an issue right handers are!

 

Stu.

[Guest]

Very interesting indeed.

So the apollo tank is unable to "buffer" the surge...

[Graham King]

The Apollo has no impact on the "surge", the surge is due to oil already in or returning to the sump, the Apollo only affects the oil exiting the sump. I think the interesting point raised here is where is the surge happening? I had assumed it was surge in the sump, and I guess it must be partially, but Stu's explanation suggests it is more to do with oil not returning to the sump.

 

I can see a dry sump would fix the issue in the sump and can't see why it would imapct the oil returning to the sump. I still don't understand why from my original post we have one engine that suffers from OP drop and one that doesn't, when they are very similar setups.

 

Graham.

[CharlesElliott]

A wet sump is a tray filled with oil and a pick up 'sucking' oil from it, pumping oil to the top of the engine and then it falls back again.

 

With high lateral G, the oil is pushed to one side of the sump or the other. Depending on the shape of the sump and the engine install, that means that oil may move away or towards the pickup point. If there is not enough oil at the pickup, the pressure starts to drop. The oil may also be heavily aerated, especially at high rpm where the crankshaft and other parts whip up the oil.

 

An Apollo helps because it removes air from the oil, so what the pickup sucks is closer to 100% oil rather than a mixture of oil and air - but it is not perfect. An Apollo also means there is more oil in the system overall which may also help in some circumstances.

[JoeC]

There is another cheaper option instead of a dry sump. Not as good as a dry sump but very common on big American V8s and should stop your oil starvation problem.

 

Accusump make an oil accumulator which effectively adds as a charged oil buffer tank so when your oil pump pressure drops it begins to discharge, keeping the oil pressure up. When the pump pressure goes back up it slowly refills. If you get one with an electric valve that switches on when the ignition is live or by a switch under the dash you also have full oil pressure before you turn the engine over.

 

They often come up on eBay etc quite cheaply.

[Jason Plato]

the gap between the oil pick up and sump can also make a difference between two engines .