Hella-Buggin'

I have 997.1 S and am trying to understand how the scavenger pump system works. I'm getting oil pressure drops in right handed sweepers and have heard it's due to the way the scavenger pumps return oil to the sump. Left handed sweepers are not an issue.

Is there one pump per head?
Is the right side on the rear, left side up front?

What's the purpose of the Bilt LN Engineering Dual Scavenger Pumps?

Why does RPM effect the pressure when combined with G Forces one direction and not the other?

Thanks

semicycler

The tandem pump (oil scavenge and vacuum pump) is in the rear right, lower side. I'm pretty sure there is another scavenge pump only in the front left. Not sure why the turn direction matters?

Hella-Buggin'

I believe it's because on a right sweeper under load, the oil pools at the back of the head. On the left side, the pump is in the front so it's unable to return the oil. On a Left sweeper, the oil is directed to the rear right corner where the pump is located.

I think the LN Dual pumps taps into the opposite side as well allowing for fluid transfer from both front and rear at the same time but I can't find much info.

Wolfk

The scavenge pumps pull oil from the upper head area and delivers it back to the sump, the pressure pump pulls oil from the sump and delivers pressurized oil to the bearings. The scavenge pump does not deliver oil to the bearings.

Hella-Buggin'

Correct.

Devil Boy

I wonder if this contributes to what sounds to me as lifter tap after I come off an auto-x course. The best I can tell is one or two of my lifters around the left rear (bank 1 cyl 1?) starts ticking only after I come off course and into grid. The noise goes away if I give it a few revs and build up oil pressure. Never happens on the street, only during extreme maneuvers associated with auto-x. I switched to 5W-50 and it helped a little but not completely. I've heard other Carreras make the same noise when they come off course so I know it's not just me. I've always assumed it was lack of oil pressure at some point during the auto-x runs keeping the hydraulic tappets from staying pressurized...or maybe I'm just completely wrong about the whole operation of things.

Hella-Buggin'

I would imagine it's related. The pump is sucking any available oil away right near #1 as it's pooled up around #3. Next time you're having fun, even on a freeway on or off ramp that you can carry enough speed through and you can see the pressure start to drop.

idlook2

Would a deep sump pan help with this? I'm thinking the increased capacity would act as an oil reserve during high G turns, and the reserve would be near the main oil pickup.

Hella-Buggin'

I have a deep sump and it's still a problem. I suppose an Accusump would compensate until the reservoir runs out.

idlook2

How big of a deep sump did you go with?

Hella-Buggin'

Mantis 1.2 Liter

idlook2

I'm surprised to hear this. See post #8 in this thread for oil pressure vs lateral G load data with the Mantis pan. Maybe the graph Ernie posted was with his 2L pan rather than the 1.2L pan? Have you reached out to Ernie?

Macster

Lifter noise after (or even during) a track session is due to air in the oil. This aerated oil gets pumped through the engine and the lifters due not like air as the air collapses and the lifter tick.

Afterwards, it takes some engine run time for the lifters to lose this aerated oil.

This aerated oil problem is rather common with other engines. Often dyno tests will find power falls off at high RPMs. Investigation finds the problem is the engine is circulating so much oil and too much oil is remaining in suspension due to inadequate oil scavenging (inadequate or in some cases nonexistent as gravity is relied upon to return oil to the sump) coupled with too small an oil supply and lousy pan baffling and insufficient (or nonexistent) defoaming capacity aerated oil is being circulated through the engine and when the lifters get this oil they collapse a bit and this affects valve timing and lift and as a result engine performance falls off.

If your engine is experiencing this aerated oil and it reads like it is you need to seriously consider a deeper and better baffled oil sump. Be sure also you use fresh oil at the track. Oil with miles on it is more likely to foam due to contamination from combustion.

Hella-Buggin'

That's why I installed one in the first place. I hadn't talked to Ernie. I just sent him an email.

My mechanic is urging me to install an accusump system to bridge the gap but I'm trying to avoid making things more complicated than they already are.

-Mark

Devil Boy

Thanks. Good to know.