Cosmo Kramer

I am getting started installing my FAST kit that I purchased from a member here. I have the instructions for the install and I am curious about the crank venting method.

The instructions say to put K&N breathers on the two cam cover outlets and plug the hoses that originally go from the cam covers to the intake/oil filler neck. Then it says to install one way check valves on any other hoses that connect between the intake and crankcase (I would take it that means the oil filler neck).

The one way check valves keep the boosted air out of the crankcase and I get that part. What I don't get is that the intake will always have false air when it is under vacuum because the cam covers just have filters attached and they don't connect back to the crankcase or intake.

I have read some threads here about designing and installing catch cans, but there is no mention of this in the instructions.

Any thoughts?

bcdavis

http://www.928gt.com/s-321-crankcase...n-systems.aspx

karl ruiter

I don't think the cam cover filters do much. Pretty much just plugs, I would guess. Not sure about the rest, though.

Fabio421

I'm having trouble following your post but I'll try to help. The first thing you want to do is eliminate the hose that goes from the throttle body to the oil fill can. Cap the port on the TB and be sure to secure the cap with a hose clamp. That is supposed to draw the vapors back into the engine to burn them and also make a negative pressure inside the crancase. Ingesting the vapors is a bad thing for a boosted car. Essentially it lowers your detonation threshhold. It's like using cheap gas instead of 93 octane.

Regarding the filters on the cam covers, I wouldn't do that. Take a look at DR's site and look at his "Sharkvent" system. That should give you an idea of what needs to be done. DR has some really nice pieces for crankcase evacuation. I bought one of his provent's but have not installed it yet because I am in the middle of painting that car. You may also want to install one of these. http://forums.pelicanparts.com/porsc...er-system.html

Cosmo Kramer

Hi Fabio

The 16V has a catch can from the factory I think. The 32V just vents directly to the intake using a network of hoses. There is a filter in the cam cover and a louver in the oil filler neck that is supposed to keep the oil out of the intake, but it doesn't do a very good job.

I think I will buy a Provent or try to fabricate something. My new dipstick tube already has a fitting attached to it to drain oit back to the pan from the supercharger, so maybe I can T into it and drain the catch can there as well.

Imo000

Ted,

There is a much better spot to drain the blowby back. I'll show you tonight.


Getting any viable information on proper crankcase venting is like pulling teeth. At least it was when I was putting my SC on. Those that had kits already on the market were tight lipped and very little first hand information was ever given. Then there are some, like Tony, that have a very nice write up on what worked for him. Then there are those that, due to financial reasons, don’t like to divulge much information on this subject. I think this has slightly changed over the last couple years but if you run into a wall of silence, don’t be too surprised.

DR

Imre,

I hope you don't count me in the "tight lipped" group as I have always been completely open about my designs. Heck I even went to a lot of trouble to make all of the illustrations showing the stock system and the proposed changes (so simple that even a caveman could understand :-) for my SharkVent system so others could use them if they didn't want to buy my system.

You can see those illustrations for all years and models at www.sharkvent.com

Here is a sample of the 89-92 system illustration...

Cosmo Kramer

Hi Dave

I have checked out your website and it has been very helpful, thank-you! I am still trying to decide how I want to design it. I have waded through tons of threads here, some say to drain back to the pan, some say empty it manually because of the condensation, apply vacuum using the air pump etc. I am swaying towards the let it out on its own pressure and run like that for now. If the oil looks clean enough I can devise something for the return to the pan. Currently with the stock system NA I have a bit of oil at the lowest point of the throttle body and a bit in the D/S end tank. I have had the car all summer and drove it about 8000 miles with no oil consumption, so it sounds like I don't have a ton of blow by.

bcdavis

Yeah, you can just dump it to the can, but if you are under boost, it may fill with oil and overflow.
If the oil and vapor is clean enough to dump back into the intake on a stock system,
then it's probably safe to dump back into the block as well. At least it creates a fairly
closed system, instead of a can you have to drain, check, etc...