Intercooler If Filled With Oil
11-30-2008, 10:42 PM
#82
I have been wondering about crankcase vent setups for a while now, and it seems as though the Z community has yet to come to a consensus on what is right and wrong. There really seems to be three options though...
1.) Fully vent the crankcase (which is being advocated here)
2.) Vent one side (driver's), but allow engine vacuum to help pull fresh air through the crankcase (through the PCV w/ one-way check valve)
3.) Closed system to provide crankcase vacuum at all times.
Which is best? I'm still waiting for someone to tell me that
I know JET MECH is a firm believer in crankcase vacuum in order to provide better ring seal and increased power, but others believe that all you need to do is evac the blowby. Most people that run setup #3 use two sources of vacuum - plenum when in vacuum, and F/I inlet (s/c or turbo filter) when in boost. Thinking about it, I don't think an F/I inlet would really provide much vacuum at all considering there is a large filter right next to it acting as a huge vacuum leak.
Since I'm running the STS system, my only source of vacuum under boost is at the rear of the car (again, probably not much vacuum anyways), so I'm currently running setup #2. I was considering doing the LT-1 smog pump setup though for constant vacuum under all conditions.
Anyways - can you guys do me a favor and figure this out once and for all?
1.) Fully vent the crankcase (which is being advocated here)
2.) Vent one side (driver's), but allow engine vacuum to help pull fresh air through the crankcase (through the PCV w/ one-way check valve)
3.) Closed system to provide crankcase vacuum at all times.
Which is best? I'm still waiting for someone to tell me that
I know JET MECH is a firm believer in crankcase vacuum in order to provide better ring seal and increased power, but others believe that all you need to do is evac the blowby. Most people that run setup #3 use two sources of vacuum - plenum when in vacuum, and F/I inlet (s/c or turbo filter) when in boost. Thinking about it, I don't think an F/I inlet would really provide much vacuum at all considering there is a large filter right next to it acting as a huge vacuum leak.
Since I'm running the STS system, my only source of vacuum under boost is at the rear of the car (again, probably not much vacuum anyways), so I'm currently running setup #2. I was considering doing the LT-1 smog pump setup though for constant vacuum under all conditions.
Anyways - can you guys do me a favor and figure this out once and for all?
Last edited by JETPILOT; 11-30-2008 at 11:46 PM.
11-30-2008, 11:08 PM
#83
Looky what I found. List of old cars with vacuum pumps installed. 
http://users.sfo.com/~eagle/figs/vacpump/vac.html
http://users.sfo.com/~eagle/figs/vacpump/vac.html
12-01-2008, 04:29 PM
#86
Jet,
Are you opposed to running an electric vacuum pump with a boost activated switch? This is the route I am going to be taking my G, with the battery relocated in the trunk - I will have plenty of room in the O.E. battery compartment for the pump and it will be concealed.
It seems like you want to go with a simple/mechanical route, which is usually the best way anyhow
Keep us updated on your project.
Thanks for the credit go-fast, it seems we can agree on some things.
-George
Are you opposed to running an electric vacuum pump with a boost activated switch? This is the route I am going to be taking my G, with the battery relocated in the trunk - I will have plenty of room in the O.E. battery compartment for the pump and it will be concealed.
It seems like you want to go with a simple/mechanical route, which is usually the best way anyhow
Keep us updated on your project.
Thanks for the credit go-fast, it seems we can agree on some things.
-George
12-01-2008, 07:12 PM
#87
I think option #2 is the best practical option. Having the driver's side open to atm, should minimize elevated cc pressure (to atm at most). Ventilation does work if you can create a vacuum source during boost and off boost (as per other recent threads). Positive ventilation has benefits, namely less oil extraction from the crankcase. I'll be the first to admit that finding a *good* vacuum source during boost is not trivial. The turbo compressor inlet does generate a little vacuum during boost, but may not be enough to compensate for blow by. With oil restrictors in place, I think its the best you can do without resorting to more elaborate setups (vacuum pumps, exhaust driven vacuum, etc). One other point is that regardless of crankcase pressure, oil pressure rises under load. No way around that. Oil pressure to the turbo seals may just be too high under boost. No way around this without some kind of oil pressure regulation feeding the turbos... It's a harder problem on journal bearing turbos since they require greater flow for proper operation - hard to minimize pressure and maximize flow.
Last edited by rcdash; 12-01-2008 at 07:27 PM.
12-02-2008, 10:28 AM
#89
You don't have a spare MAP sensor that you could hook up to the valve cover piping and log, do you? That would be invaluable data, esp. since you'd be tracking the car and stressing the motor at high rpms continuously.
You might still get oil in the piping, but if CC pressure never rises above atm, then it's likely another cause (i.e. turbo seals or oil pressure)
You might still get oil in the piping, but if CC pressure never rises above atm, then it's likely another cause (i.e. turbo seals or oil pressure)
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350z, clean, engine, filed, filled, filling, fulled, innercooler, intercooler, intercoolers, oil, seal, turbo
