Inked

Oil levels for track racing

100 posts in this topic

Hi all,

 

I have entered into the Super lap race at Manfeild in March and I am just getting a few things ready on the car. I am a little bit worried about all the talk going around how that track is a "subie killer"

 

A couple of people have told me that if I am not running a baffled sump to put some extra oil in the engine before going on the track to stop the starvation, has anyone had any experience with this or can help?

 

TIA

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Put half a litre extra oil in... don't drive hard around Higgins corner...  and in fact just try and cruise round it... and you hopefully will be fine.

 

Check the oil level before every track session as well as it can pour out of the left hand head breather.

Edited by Loren
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23 minutes ago, Loren said:

Put half a litre extra oil in... don't drive hard around Higgins corner...  and in fact just try and cruise round it... and you hopefully will be fine.

 

Check the oil level before every track session as well as it can pour out of the left hand head breather.

 

Cheers for the reply! I haven't raced on this track before, is Higgins corner the one coming onto the straight?

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Think some of the guys were putting a inline irrigation tap on the breather to stop it doing what @Loren said.

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Go baffled sump bro! cost much less than a rebuild :P then you can fang fang fang ^_ ^ (disclaimer - fang not covered by warranty) 

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Why not buy the baffled sump?

Hampton is the same, seen many dead wrx's there on track days. 

You also get more oil in the intake running too much oil.

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Changing out a sump is a bit more of a mission than adding half a litre of oil. Depends how long you have before the event, and how often you plan to do things like this. An easier option might be a small drain back tank above the motor collecting the breathers, which is teed to a catch can if it overflows (a la Tony's old setup, which incidentally I think Viv has now). He had it where the top mount goes though, so might be tricky to find a good spot.

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is drain back fast enough? I'm pretty keen to build one but it was more for daily use not track.

sump swap can't be the longest job.

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It's not the longest job but, it's awkward and terrifying for your hands. Drain back is proven to work at Manfeild on slicks.

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Having started to pull my sump tonight I can confirm it’s a pain to do with the engine in place. Really need to lift the engine a bit to get to the back bolts which is a pain on it’s own. Didn’t have to in the end thankfully.

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2 hours ago, Inked said:

 

Cheers for the reply! I haven't raced on this track before, is Higgins corner the one coming onto the straight?

 

It's the RIGHT hander onto the back straight. You can be pulling lots of Gs for what feels like a long time and with a

lot of throttle and high revs... try not to do that :) Killed my motor even with a good sump as lot's of oil poured

out of the head breather into the catch can.

Edited by Loren
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38 minutes ago, Loren said:

 

It's the RIGHT hander onto the back straight. You can be pulling lots of Gs for what feels like a long time and with a

lot of throttle and high revs... try not to do that :) Killed my motor even with a good sump as lot's of oil poured

out of the head breather into the catch can.

Awesome I'll make sure to just roll the corner. It's my first track day so doubt I will go to fast anyway haha 

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Was worried about my car there, but chatted to a mate, this is more a boxer engine issue right? and why? thin sumps cause the engine sits low ? 

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4 minutes ago, Not_Sean said:

Was worried about my car there, but chatted to a mate, this is more a boxer engine issue right? and why? thin sumps cause the engine sits low ? 

Form other cars it can be about the head oil drain design. Some Evos had the sump pickup more to one side and forward that was the issue at Hampton.

I found the Subaru sump is quite deep as the exhaust hangs down below the engine so there is more under there than you expect.

 

guess from @Loren comment the heads being low and on the sides caused the oil not to drain back and blow out the breather.

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On 2/13/2018 at 7:41 PM, Loren said:

Put half a litre extra oil in...

I wouldn't do that, there's a reason for the maximum mark and you might just end up killing your engine for another reason (too much oil).

If it's your first track day you are probably better off by just checking that the oil level is at the maximum and not going too fast in that corner.

 

I'm not familiar with Manfield, is the problem only occurring if you have a really high level of grip or even with basic road tyres ?

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A great many of us have done a great many laps of Manfeild with an extra 1/2 litre above full. This has also been recommended to Wellington members time and again by more than one well known and respected Subaru engine builder. Experience and impirical evidence always trumps conjecture in my opinion. Each to their own.

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Been pretty common advice over the years, adding an extra half litre, haven't heard of any negative results.

I've always run my oil slightly over full in my Subaru's.

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Hmm that's kind of surprising to me. I know there's some margin for overfilling by design but I would expect the margin to be closer to 1/4 litre than 1/2 litre.

AFAIK the main risk is that the oil can get aerated and turn into foam which doesn't lubricate properly.

Only time I've seen someone with overfilled oil at a track day, he had smoke come out of the engine bay and we discovered that there was oil all over the place. The oil probably came out of the breather. I reckon he had something like 1/2 litre above full but it was an 86 (Subaru FA20 engine), might be different with older models.

 

EDIT : Oh and he had smoke come out of the exhaust as well, this is what I noticed first

 

And do you guys drain the extra oil after the track day or leave it like that ?

Might be bad in the long term, just saying.

Edited by delta
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1 hour ago, delta said:

Hmm that's kind of surprising to me. I know there's some margin for overfilling by design but I would expect the margin to be closer to 1/4 litre than 1/2 litre.

AFAIK the main risk is that the oil can get aerated and turn into foam which doesn't lubricate properly.

Only time I've seen someone with overfilled oil at a track day had smoke come out of the engine bay and we discovered that there was oil all over the place in the engine bay. The oil probably came out of the breather. I reckon he had something like 1/2 litre above full but it was an 86 (Subaru FA20 engine), might be different with older models.

 

EDIT : Oh and he had smoke come out of the exhaust as well, this what I noticed first

 

And do you guys drain the extra oil after the track day or leave it like that ?

Might be bad in the long term, just saying.

 

 

Yes if you really over fill the sump the crank will be picking the oil up and chucking it everything. 1/2 litre appears to be fine though.

If you want to understand why the oil spews out of the heads in a big corner watch this. 

 

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each generation of engine will be slightly different in the way it pumps and drains oil from the heads.

I've had somewhere over fill oil in mine and it wasn't much more than 1/2L and it increased the oil coming out the breather greatly.

didnt smoke so wasn't externally noticeable but coated the intercooler inside. Only reason I noticed was the intercooler had a small leak dripping onto the down pipe. once drained down to the correct level it hasn't coated the intercooler inside again.

 

 

There is no evidence to prove extra oil helps or hurts. The whole thing is conjecture.

Unless you're going to run exactly the same engine with and without the extra oil, at the same speed over the same line, for the same number of laps you're guessing the oil saved the engine, of it was ever going to die.

 

With @Loren example then extra oil and baffled sump would just delay the transfer of enough of the oil into the catch can before it died. But if the catch can drained back then it may have survived.

 

@Inked do your own testing before you hit the track, put some extra oil in there and see how your engine responds. Check the intercooler before and after, same with the catch can if you have one. 

 

 

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Unless you have a baffled sump and an efficient breather system you are best to avoid building centrifugal forces..

The two corners that need attention are the entrance and exit from the back straight..

At Higgins use all the track by approaching on the far left and turn into the apex and sweep out to the outside on exit..

Avoid max revs by changing up a gear if possible thru the apex..

The sweeper can be taken with a "motorcross" line..

Enter down the inside and brake across the track to the outside ,"the berm"..

Then turn into the apex and exit to the outside of the corner..

Both of these methods will minimise centrifugal forces..

Remember the experiment you did at school with the half full bucket of water swinging around and the water staying in the bucket..

Avoid this effect....

 

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@Gripless All of you guys wanting to push your cars really hard should get rid of the recirculating breather system anyway. 

Edited by Loren
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1 minute ago, Loren said:

All of you guys wanting to push your cars really hard should get rid of the recirculating breather system anyway. 

 

Totally agree..

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Thanks to all off you for the replies, this is something that is making me nervous ha ha. I have spoken with Chris who tuned my car and he said extra oil wont hurt it but unsure if it would still stop it from having issues if I went through higgens to fast.

 

I think the fact I will be on street tyres and this is my first time hitting a track properly will drop my chances of being to fast that I run into this issue (fingers crossed) I have got some extra oil so will top it up and see how we go, by the sounds of it and as @pedro mentioned I will try to run nice lines as well as more rolling through those corners rather than trying to power through them.

 

If my engine runs a bearing its going in the shed until I can stand the sight of it xD ha ha ha

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On 2/13/2018 at 10:20 PM, Loren said:

 

It's the RIGHT hander onto the back straight. You can be pulling lots of Gs for what feels like a long time and with a

lot of throttle and high revs... try not to do that :) Killed my motor even with a good sump as lot's of oil poured

out of the head breather into the catch can.

 

yep.

advice i got from seasoned manfeild pros was to use a higher gear than usual when cornering.

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