kgkern01

iTrader: (10)

So I finally ditched my open breather setup after oil splashout at an autocross caught a small fire. I just changed it to 5/8" lines going from each valve cover, to a 'T', then 3/4" hose to a catch can with a breather on it, located in the driver front 'CAI hole'. I also already have a small air/water separator inline with the stock PCV from side of intake to under the TB to keep oil out there.

I saw on turbobuick.com, ( http://www.turbobuick.com/forums/gen...-pump-how.html ) as well as read elsewhere online, where people are using GM AIR pumps in reverse to help evac some WOT crankcase pressure. I understand the AIR pump is not as good as say a purpose-made pump, but I believe in my case it should at least help a little. Even 4-5" of vacuum is better than no vacuum to help with pressure.
I have taken my stock AIR pump (same one used in the above link), removed the foam, cleaned it, greased the bearing, resealed, and tested it ok. I want to use this pump to help during WOT, but am unsure how to set it up.

I am N/A, and I understand that under idle, cruising, high vacuum conditions that this line currently supplies fresh air to the crankcase then out the stock PCV into the intake under the TB, but then at WOT, pressure can cause the system to work in near reverse, pushing some air OUT of the valve cover into the catch can. This is where I want to vacuum.

So my question is this: Do I run the vacuum only at WOT, say via a switch, or since it only pulls a few " of vacuum, do I run it full time, and if so, where would the air enter the crankcase, from the blowby past the rings?

quik95lt1

iTrader: (7)

yes air gets into the crankcase by the rings......that AIR pump will pull 2-3" if ur lucky........i would trigger the pump at WOT if it were me.......i see that thing burning out if it were running all the time

fwiw a purpose belt driven vac pump like the one i run on mine is good for up to 15rwhp or so......i saw 10rwhp gain on my old 355.......prob be worth more on my new motor also allowed me to run low tension oil rings.........i pull 3-4" at idle and about 18" at WOT

kgkern01

iTrader: (10)

Well I plan on keeping AC because I do drive it on the street and idling in traffic on 90*+ weather sucks without some cool air blowing. I do know that some other car's AIR pumps do pull more vacuum than the modded LT1 AIR pump, which I've read people have measured them at 3-5" vacuum. For now, I would assume that would be better than nothing until I can find one of the better electric pumps. Supposedly the old 4/6/8 Caddy air pumps can pull up to 10" vacuum, so later maybe I will look for one of those.

As far as the WOT switch to activate the pump, what would you suggest? I think that a switch that could trip a relay at say 4v from the TPS sensor would be good, or would a switch attached to the throttle body be just as effective/easier/cheaper? I don't want to spend a lot of money for just a WOT switch.

1badzee

iTrader: (12)

Micro/WOT switches are really cheap. I would just mount it near the throttle body and have it manually close the circuit at WOT or near it. Another option is somehow rigging it under the pedal. Not sure how else you could do it.

kgkern01

iTrader: (10)

I'll get one of those, just looked them up, they're pretty cheap.

quik95lt1

iTrader: (7)

yea thats your're best bet.........if not you'd have to build i circuit to do it.......need a couple of resistors and a diode the easy way.........an ic chip and a few resistors the good way lol

speed_demon24

iTrader: (6)

How's the crankcase going to vent when the pump is off?

kgkern01

iTrader: (10)

The stock PCV is still there, where it draws vacuum from the front of the intake manifold and pulls crank gas out from the drivers side of manifold

speed_demon24

iTrader: (6)

Then the vacuum pump won't be pulling any vacuum, it will just be creating a huge vacuum leak when its running.

quik95lt1

iTrader: (7)

^ hes got a point........you can do one of two things.........one seal off the system and run the pump on all the time.........or two run a breather in the other side to vent the part throttle gases out......only issue is you wont be able to generate an actual vacuum in the sytem with a breather in there.........

kgkern01

iTrader: (10)

Well I tried running just the sealed breather caps to the catch can, to allow pressure to vent as with the previous breather filter system, but avoiding the oil mist and splash out that the breathers allowed. However, pressure backup seemed to be worse with the dipstick popping out. I just found out why the new 2 sealed breather caps going to the catch can were backing up pressure, they are apparently baffled with only a slit for an opening and filled with foam, which is restricting the pressure trying to vent out of the caps and thus popping the dipstick up.

Going to try just the catch can setup again after I open up the baffle and remove the foam to remove the severe restriction.

ArklaTexan

iTrader: (24)

dont mean to bring a dead thread back to life, but I need some help.

I have a 410cu 11.5:1 motor with 251/266 .638/.621 cam that has little to no vacuum at idle and is hard to use the brakes. I bought a Comp Cams 5500 unit and have it Tee to brake booster and the back of the intake.

The motor is as follows. Rear Driver Valve cover has breather, Valley Cover has a breather, Intake to TB is connected. Passenger valve cover to CAI.

how do I make this function properly?

quik95lt1

iTrader: (7)

two TOTALLY different vacuum sources and circuits.......the vacuum pump for your brakes should be on when you hit the brake pedal....the vacuum for the crank case should be effective all the time and limited to 15-17inhg