Did you monitor the oil level in the sump Eric?

 

I aggree

 

We have also just built a Type-25 with the Cosworth oil baffle plate installed which supports Eric’s finding.

Car:
MY07 Subaru Impreza STI with narrow sump.
Engine:
Type-25 Cosworth Long engine
Cosworh Subaru (ej20/ej25) oil control baffle
Silkolene pro s 10w/50 fully synthetic oil

Cosworth baffle oil pressure readings.
Water temp degrees c >>>> oil pressure x100kpa >>>> engine rpm
20.. 5.9 1500
30.. 5.9 1500
40.. 5.9 1500
50.. 5.9 1300
60.. 5.9 1100
70.. 5.9 880
80.. 5.4 800
90.. 3.9 800
95.. 3.2 800
96.. 3.0 800
Fans cut in
93.. 2.7 800
95.. 2.6 800
Fans in and out
93-96.. After 20 mins idle >>>> 2.3 @ 800 and stabilised.
Hot rpm held 3000 >>>> 5.9 and stable
Return to idle after 1 min >>>> 2.0 @ 800

Dyno run with oil temperature probe.
Oil temp 85 degrees C, oil pressure 5.9 @ 3000
Oil temp 79 degrees C, oil pressure 2.0 @ 800

I think it is safe to say that this Oil Baffle plate has no the effect on oil pressure we usually see on engines fitted with the Narrow sump

Iain

 

hmmm the plot thickens

 

Some good data there Iain

So WTF was going on with the car that had a problem

I was planning to fit one of these so it would be good to know what the issue was ?

 

weird.

but does it stop oil surge which is the point of it ?

 

Did you monitor the oil level whilst it was running at higher rpm Iain?
What were the readings at 7500rpm?

 

In all fairness, Iain that's not what it shows though is it.
It only shows that it didn't react the same way as the one we fitted it to (twice, with identical low pressure results, which cleared back to "normal" as soon as it was removed)?

Unfortunately we didn't get a chance to look at it in any greater depth as we would have loved to have done as the customer wanted his car back to prepare for Time Attack, I'm sure that Cosworth will be pursuing this matter which has been acknowledged by them as "not a build problem" until they've determined what the actual cause was?


Mike.

 

Will let you know the higher rpm readings when it is back on the dyno and it is road tested John.

 

Thanks Iain.

It would be very useful to monitor the oil level, that will show you if there is a restriction problem better than oil presure.

A Bench dyno would allow checking for oil level far easier than doing it in the car. Has Cosworth done some bench dyno testing and monitored the effect on oil level?

 

Oil pressure remained consistant all the way to the Cosworth 2.5's 8,100rpm redline and on extended road test

I would image Cosworth's pressure figures came from the MY08 2.5 engine they are currently have out for dyno testing but would need to check.

Iain

 

Thanks Iain.

 

Our data entirely supports that found by our good buddies at Litchfields. We've had a 2 litre STi8 running around quite happily on 450 bhp since it was fitted.
We have three more cars to go very soon with Cosworth baffles, and we don't expect any problems.

 

An oil presure gauge needs fitting to these cars until the problem Dynamix experienced is explained, IMHO.

 

A common sense measure at any time of course!
Personally, I don't think we'll ever know the answer to that one. We just can't replicate what happened to D's car, and so far, neither has anyone else.

 

I think I may have found the reason for my lack of oil pressure with it.



Whipped the sump off today to do some baffling but found a small crack in the oilpipe that may have been opened up more by the cosworth tray.

It does look like a design fault in the pipe as i have heard of another splitting.

I am going to re-fit the Cosworth tray tomorrow and will report back

 

Well spotted !

If its not too late, consider the Cosworth extra capacity 'big wing' sump, it comes with a new pick up pipe too

 

at last the mystery is solved, well found.

 

Iain,
As a matter of interest is this Cosworth plate a much cheaper version of the PowerStation Baffled sump on my car (as regards to what it does).... or is the PowerStation baffled sump solution still the best bet for hardcore track attack (not that I would know of course lol)?

 

well.... I hope it is solved.

I will re-fit tomorrow and make sure all working fine but it seems likely that this was the cause. I have only ever heard of one other pick up pipe splitting and that was on an 06 car that a friend told me about last week.

 

I do hope that that is your problem Dunc, and a good job you found it too...

Potential time bomb there..

Look forward to the results...

 

Yeah, it could have been very very nasty. Good job I wanted to do some baffling of the sump.

 

I think it explains a lot - although it is such a random fault (i have only every heard of one splitting and that was on an 06 car too).

The funny thing was... the choice was either to:

- lift the engine up 2 inches so undoing the engine mounts, finding a hoist and listing engine so that the sump would clear the pick up pipe, or

- remove 3 x 10mm bolts to remove the pickup pipe.

Good job I am lazy

 

Strangely someone I know (06 STI) has just had a new engine supplied and fitted from Subaru,after experiencing the same problem... (No Cossie bit tho'.)

Duncan

 

If you think that's a small crack you'd be very popular at a weight watchers convention.

You are very lucky, not much more running and that would have failed completely. That would certainly cause issue you had if the crack was in free air and not under the oil level.

 

A proper baffled sump is far better than fitting this tray, mainly because you get a direct feed to the oil pickup pipe, plus better control of the oil under surge around the pickup because of the design of the bottom feed to the pickup and the way it's mounted inside a surge tube.

The cosworth plate is a half way there solution, as it does nothing to improve the oil flow around the oil pickup, in fact it's introducing a restriction in the path the oil has to travel to get to the pickup, small as that restriction should be, but it's there, a good baffled sump directs the oil to the pickup by an unrestricted path.

It should improve some of the more severe surge issues but it's not a substitute for a well designed baffled sump IMHO.

 

Lucky is my middle name at the moment

Once I have tested the repaired pipe and the tray combined in normal running and assuming it is fine during this, it will be very easy to compare a before and after effect of the tray at preventing surge/sloshing. I will of course post the full results here. If it works well then I will be the first to say - 'well done cosworth'

 

Does the 2.5 oil pick up differ from any previous version?

 

yes - it is a completely different design to work with the different sump floor and has shrouding around the pick up gauze to help aswell. I guess it is longer though and maybe this causes extra strain on it in some circumstances.

 

Well, that's answered that one then!
Credit to Duncan for the discovery and admission.