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Dry Sumping Debate..........

25K views 148 replies 43 participants last post by  wozzy 
#1 ·
This question is pretty close to my heart at the moment, at I have just had a turbo and crank expire after my Spa and Nurburgring trip in May. There may be a possibility that I suffered oil surge most probably at Spa due to the very fast and sweeping nature of the circuit.

We have seen that due to evolvement in suspension and tyre grip over the years, that when Evo's are used in real anger such as Time Attack and Trackdays, these engines suffer oil surge on right hand bends.

AMS has devised a sump with an extra 1.5 Litres of oil capacity and a few other tricks, but I'm led to believe that this isn't the answer either, and even if you had an AMS sump fitted, there is a potential for the engine to suffer oil surge :confused:

Most of the Evo Time Attack field is now going dry sump, to hopefully eliminate this phenomenon, but when is dry sumping really necessary ??

Are we saying that any Evo used on track that had more than a certain "G" on right hand bends could have most likely had the big end shells pick up ??

How would you know, without removing your sump and and taking your big end caps off to inspect your shells, ultimately your car could have worn shells now, and be in the same predicament that my car was ??

I'm just trying to get my head around spending in the region of £7000 for my replacement turbo and engine refresh which will probably require a new crank, unless I decide to regrind the old one.....

Would be good to have a focused dry sumping debate once and for all, to see at what level we need to go this way, whether it's G-Force, power levels etc, etc....
 
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#127 ·
Hi Guys,

During the timeattack in Assen I also had a problem with the oil pressure. Looking at the data files I discovered a low oil pressure in corners turning to the right! During the straights and corners to the left, the oil pressure is about 6 bar but in or after a corner to the right it drops to 2,5 bar (have seen even lower oil pressures)! I have placed the marker at points with the lowest pressure (see circle on track map).







Also when the oil is hot the engine runs on a low RPM (950) the oil pressure drops below 1 bar. But I don't know if this is the same problem. The oil in the engine (of the Evo VIII) is Castrol 5W40 and is just below max on the dipstick. Pickup and Pan are standard.

I don't have the budget to go dry sump, but I can change the pickup and pan. If I can improve the oil pressure with 1.5 bar I am happy. Is it possible with wet sump? What is the best way to go?

Regards,
Twanny
 
#128 ·
Twanny

Im sorry to say you have no option but to go dry sump if you want to keep your engine in one piece! No wet sump will fix this issue you have.

Furthermore the low oil pressure on hot idle is just a function of low rpm and hot oil with low gear speed on the stock oil pump. It is not related to the oil surge/aeration issue that you have logged. However our dry sump kit sorts this issue out also.

Cheers

Si
 
#129 ·
First of all, sorry for raising this from the dead. But it was the closest I found in a search and my question is related.

At how much lateral G does this start to be a problem?
The graphs above indicates closing in on 1.2G (and dramatic pressure loss) and Si's answer is making me worried.

This is a simple graph from my last track day showing lateral G around the track. Up to 1G is green, >1G is yellow and >1.25G is red.

As you see it appears I'm running above 1 G in pretty much all corners, peaking above 1.25G.
 
#146 ·
Question for you very knowledgeable chaps, reading this lot from the start I don't know if I should be worried or not.
I have an Evo 9 and like to do the odd trackday, is the above problem something I'm likely to have on a car with Michelin Pilot Sport 4 tyres or isn't there enough lateral G being generated for it to be a concern? The corner in question is a long (about 250m long) 180 degree right hander.
If I make sure I overfill the oil will I be ok? Would a baffled sump be a good solution in my case where it'll only ever run road tires.
 
#147 ·
The conventional wisdom is that you'll most likely be ok unless you were to run slicks or very sticky semis. In terms of lateral G numbers, any sustained right hander where in excess of 1G is being generated should probably start to sound warning bells.

Just to give a bit of context, I do a lot of circuit data logging using mostly the Racelogic Vbox system (so GPS only data) and on a reasonably well set up 9 on slicks I would expect to see 1.2G up to a max of around 1.5g.
 
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