sand_man

The following is a thread on Pelican about doing away with the cam driven turbo scavenge pump and going gravity feed into the front of one of the chain housing covers. What say the 930 hudu-gurus about this? I was having no problems with my pump. I'm curious only because I like to keep things simple...gravity seems simple enough for a pea brain like myself! Is it doable, or will the oil back up into the turbo?

http://forums.pelicanparts.com/showt...hreadid=251387

srf506

I'll let the gurus give all the technical and physics laws regarding why this will/won't work. But, I'll chime in to say the German engineering mentality doesn't usually support adding any unneccessary complexity to a mechanical item unles called for. Therefore, I would be inclined to say "myth busted."

sand_man

Has the 911 Turbo always had a scavenge pump...i.e. how were the early 3.0 cars setup? I tend to agree with srf506 regarding German engineering...but you never know about some of those band-aid fixes <<cough>> SMOG-PUMP<<cough>>. Obviously the scavenge pump seems like a good measure. I'm just curious, I guess. What did the race cars run with?

kellcats521

Based on my service manual, the 930 has always had the scavange pump. The problem with a drain line into the case is this - the case is generally under positive pressure when the motor is running. Granted the pressure is vented to the atmosphere or the intake (using intake vacuum to evacuate the positive pressure), but putting the future of your turbo on the ability of the PCV system to remove positive pressure to a point that 'allows' gravity drain the oil was obviously not a better idea at Porsche.

srf506

Ya know sand_man that would've been a medical term if you'd just said "turn your head to the right" prior to the first cough ;-)

jwl

All I know is that if the scavange pump is not working oil will leak thru the turbo, into the intake and cause major fouling/smoking and possible turbo damage...I found this out the hard way. I'm with Kellcats521 on this one!

Kevin

Another thing to remember is that as your engine wears, blowbye increases crankcase pressure. This pressure works against the ability of the turbo to drain it's oil.. Thus causing a turbocharger failure. Most people think that the failure is directly related to a leaking turbocharger, however if pressure is keeping the oil from freely passing through the turbo.. Lubrication and cooling suffers.. You will have accelerated bearing and seal wear.. Most options to plumb a good pump is/are cheaper than buying or repairing a failed turbocharger..

ngoldrich

Early 930's had turbo scavenge pumps. My first 930 was a 77 3.0 and it had one...

Norm

sand_man

In case you guys are curious, I like to post threads like this because it sort of creates a paper trail of sorts for those who are new to these cars and have these types of questions. If they bother to search maybe they'll be rewarded with the info they're looking for.