Crankcase evacuation (pcv alternatives)

[MikeRenz]

Well I removed my pcv system, and really don't want to reuse it. I've been searching around for other options. Most pumps are either expensive, or sound too shady to actually work/be reliable. And I don't want to just use a breather.

Tonight i came across this:
http://community-2.webtv.net/PAGEBUILDERPICS/CRANKCASEEVACUATION/

I don't see why it wouldn't work...the only downfall being tapping into the downpipe, and getting the innards of the piping dirtier faster (who cares). Has anyone tried this method??

Apparently diesel trucks use this method quite frequently....can anyone vouch for that? If thats true, my brother can definitely get me the setup off a truck for very cheap since he sells all that shit.

 

[20psiGMC]

Yep, that’s half of the Moroso Crankcase Evacuation kit:

Moroso Evac Kit

I used this set up on another project, and it worked well.

I just happen to have one of the check valves lying around, so I’m going to come up with a 304L pipe nipple when I get to fabricating the DP and give it a try.

I think it will work well in our application, replacing the “under boost” part of our PCV system. You may want to retain part of the stock set-up for evac out of boost, or use a breather...

 

[Daron]

This type of evac may not work in a SyTy downpipe, if you have a Cat and or Muffler. The back pressure could get significant under high boost conditions. 12 inches or so from the end of the exhaust is usally where these are mounted.

 

[20psiGMC]

Hey Daron!

I hear ya. I’ll be running no cat/token muffler. Even at that, it will be a question of whether the velocity (Bernoulli’s principle) will overcome the pressure. I’m betting at higher engine speed, it will…

A line from a cap on the nipple to a boost/vacuum gauge should let me know…

 

[kbbeckius]

I wonder how well it would work under boost? Anyway you can probably make it from parts from the auto parts store/salvage yard. The breather used is called a "Chrysler" style, and the check valve is used on A.I.R. injection system manifolds. I'd be worried that it will suck oil vapor and contaminate the cat/muffler.

Thx Brad

 

[20psiGMC]

It should work best under boost; as the exhaust gas velocity is higher. I am going to retain the stock PVC set-up for operation in vacuum, and just connect the evac line to the one that would usually puke into the intake tract just before the turbo. This is probably not an option if you have to run a cat. Hopefully most of what makes it into the exhaust will burn/evaporate, so there shouldn't be too much “build up”. Even if there is, I would a lot sooner have it there than gunking up the blades of the compressor, bringing down the efficiency of the intercooler, and diluting the intake air.

If it turns out that it doesn’t generate a vacuum, I’ll put a cap on the nipple and start looking at vacuum pumps…

 

[jwaller]

I have about 1.5 ft of the stock DP...and with just that I still get 10-20psi in the exhaust system under full boost.....

 

[rockvillespeed]

known issues with header evacs on street cars:
1 - they require basically zero backpressure to be effective - good luck on our shit
2 - the check valves go frequently