crankcase evac

[murderwagon]

So im about 80 percent done with my total rebuild of the 70 wagon. im about to put the engine back in and i have been debating a crank case evacuation system with a check valve in the exhaust at a 45 degree angle. I have done all the research and i cant seem to get a straight answer. So here it is IS IT WORTH IT? i plan on running a 2 inch exhaust small resonator and a turbo muffler . engine is a l20b stock bottom end (low mileage) mildly shaved head, a mild cam, and weber carb. any one try this? and if so results would be appreciated

[datzenmike]

Nissan already has a system for this called the PCV. All engines have the necessary plumbing hoses and one way PCV valve. It's effective and passive in operation. Better yet it's already there and working so you don't have to re-invent the wheel. So no, it's not worth it.

[okayfine]

So no, it's not worth it.

And even if it might be, you didn't define "worth" in your opinion, so it would be impossible to say.

[510wizard]

Well, back in the day when I was building hot VW drag motors, we used a system that we called "pan vac ". This system was different from a PVC system, basically a venturi was built into the collector of the header which created a large vacuum at this area then went thru a one way check valve ( like an EGR valve) to the crankcase. So basically the crankcase was running in a large vacuum, which in theory the crank, rods, etc are not fighting the pressure of the reciprocating mass. The faster the engine turned the larger the vacuum. One problem is the blow by is getting blown out into the atmosphere, (not re burnt like a PVC system), which is not good from a clean air standpoint. One nice thing about it, is there are no leaks from the seals and gaskets. A leak free engine. In fact after running the engine for any length of time you can pull the drip stick and hear the vacuum in the crankcase. Of coarse the tighter the engine is the better, we only used Total Seal rings because of their very low blow by.

[banzai510(hainz)]

my 521 using a stock type set up
yes use the PCV.
On sidedraft set ups I open vent the crankcase you use a catch can set up.

Just depends if your using the old L20 exhaust manifolds and intake set up.
I use the early l16 set up myself and if you have a square port head to use close to the same.

L20s the metal tube comming out routes to the back and up(Funky)

[murderwagon]

Well, back in the day when I was building hot VW drag motors, we used a system that we called "pan vac ". This system was different from a PVC system, basically a venturi was built into the collector of the header which created a large vacuum at this area then went thru a one way check valve ( like an EGR valve) to the crankcase. So basically the crankcase was running in a large vacuum, which in theory the crank, rods, etc are not fighting the pressure of the reciprocating mass. The faster the engine turned the larger the vacuum. One problem is the blow by is getting blown out into the atmosphere, (not re burnt like a PVC system), which is not good from a clean air standpoint. One nice thing about it, is there are no leaks from the seals and gaskets. A leak free engine. In fact after running the engine for any length of time you can pull the drip stick and hear the vacuum in the crankcase. Of coarse the tighter the engine is the better, we only used Total Seal rings because of their very low blow by.

i don't run a pcv. it doesn't make sense to me to pull contaminated air into the intake. A crankcase evac system, as described above, in theory is way more efficient and will give you power with the expense of a possibly smokey exhaust. my engine is tight, low mileage, slight blow by, just wondering if there is any down side of it. i have run crank case evacs on v8s and some vw's in the day. just wondering if any body has done this to an "L" series? and if so results.

[banzai510(hainz)]

Results= less stinky, at least for me

Horse Power Gain? Only in ones mind
Its only L Motor, does it matter is the real question I guess

If your using a down draft carb I say run it.


what ever you do dont plug it up!!!!!! Seen a spark plug plug in one crank case tube!!!!!!!!

[okayfine]

it doesn't make sense to me to pull contaminated air into the intake.

Sure it makes sense. You may not like it, but that's completely different.

If you're looking for experience, you probably won't find it in the 510 arena. Most everyone runs a PCV unless they're running a side-draft manifold that doesn't incorporate the boss. A couple people run a catch-can.

[murderwagon]

ok im doing it. ill post results. thanks guys and okayfine you are correct on that. it may make sense i just dont like it.