Thought I’d have a go at asking here. Have a E34 540i manual running 14psi of boost with a vortech b3.
At a trackday last Saturday unfortunately oil started leaking out the discharge pipe to atmosphere from the catch can.
I was looking at perhaps running a vent direct from each cam cover then running a vaccum pump to keep the crankcase back in vaccum rather than positive pressure. There is not a huge amount of info about this on the net. From the limited info about it most seem 14-16” of vaccum will also be beneficial to power generation and help minimise “blow by”.
Anyone else had experience with this. Is an electric pump sufficient or do I need a mechanical belt driven one.
Thanks in advance
BMW’s
90 E34 M5
84 E24 M635csi standalone ecu with coil on plug
94 E34 540i/6 SC 5-17psi Flex fuel/standalone ecu
97 Z3 2.8
97 E36 M3 euro SC still u/c
OTHERS
11 Audi S5 APR stg2
19 Volkswagen Amarok V6
I don't know about an electric pump but my engine is drysumped and I have the vacuum control valve set to 7psi. I can tell you that with 3 stages of scavenging, at 900whp the vacuum was dropping. I've since changed from 1.2" spur scavenge stages to 1.5" roots. I don't know what kind of electric pump you'd need to be able to do the same. But you also need to address a way to separate the oil you will be sucking out. There will be a bunch suspended in the crank case that will condense after you draw it out but there is also a bunch of it being flung around so unless you have a good baffling system, the oil will be getting spat out of your suction port into your pump. Drysump pumps are meant to scavenge oil and also draw vacuum so the oil is then deaerated.
Last edited by TheJuggernaut; 04-23-2019 at 12:38 PM.
I had the same issue the last time I was at the track. I recently changed the catch can to a sealed one that could connect to the intake tube pre-supercharger for vacuum. Hopefully this would help when I have the car running again.
-Phil
The only problem with connecting to the intake is I run a blow through MAF. It would get coated in oil film.
BMW’s
90 E34 M5
84 E24 M635csi standalone ecu with coil on plug
94 E34 540i/6 SC 5-17psi Flex fuel/standalone ecu
97 Z3 2.8
97 E36 M3 euro SC still u/c
OTHERS
11 Audi S5 APR stg2
19 Volkswagen Amarok V6
You might be able to use a secondary-air-pump. They should pull about 4 in. some drag racers use vacuum pumps that run off the accessory belt. not sure how well they work for street application.
-Phil
The electric pump triggered via a low boost pressure switch seems like the go. Thanks for everyone’s help on this subject. Next question so what pump is the best and where do I get it from.
BMW’s
90 E34 M5
84 E24 M635csi standalone ecu with coil on plug
94 E34 540i/6 SC 5-17psi Flex fuel/standalone ecu
97 Z3 2.8
97 E36 M3 euro SC still u/c
OTHERS
11 Audi S5 APR stg2
19 Volkswagen Amarok V6
I'm about to put in one of these Cobra pumps. Hopefully it works. There is all sorts of stuff on the net about these units.
https://www.m5board.com/vbulletin/e3...rger-m5-2.html
TEC-3R, T4 GT40, WISECO, EAGLE, SUPERTECH, O-RING'D "FRANKENSTEIN" STROKER.
Those Cobra pumps look pretty cool. Only $80 on ebay.
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