I'm getting ready to boost my lq4, do I need to remove the solenoid from the intake manifold and put a filter after the canister or is it fine to leave it? Heard something about boost pressure on the tank or something

 

You'll hear a lot of different opinions, my opinion is that for a street truck you can't beat this routing. It's cheap, easy, and you won't smell oil at idle. For an all-out performance build the general opinion is that crankcase mist should not be recirculated back into the motor through the turbo inlet, as it can cause detonation.

 

So the check ball is there to keep boost from going back to the fuel tank I assume?

 

I misread your post! I haven't heard of anyone having boost leak issues at the evap solenoid, myself included. I'd be interested to hear from others.

 

So you left your evap completely alone? And your post wasn't wasted, your diagram was another question I had too.

 

Yes I didn't touch my evap, the entire system works like factory including the charcoal canister and solenoids under the bed. I've left the filler neck cap off before and it popped a code immediately - P0455, so I'm fairly certain the system works

 

The issue with the catch can picture above is you are only drawing vapors out under lower power and not venting pressure anywhere but into the turbo under boost. This is exactly what you don't want. Will be fine for a 500hp build, but more than that I would use a true vented setup.

 

For the oil vapors you saying the 2ñd fitting on the catch can should just have a filter

 

He is saying both valve covers simply have hoses that go to a 2-fitting vented catch can (or two individual vented catch cans). You'll notice that some high HP builds will weld a new -10 or -12 fitting to the valve cover as the factory vent tubes are pretty small. *Technically* you could do things the hack way and leave both valve covers completely vented; no filters, no hoses, no nothing (only if you're speed density). That's the way "Denmah" does it (search his name on LS1tech).

 

I'm saying you need to give the air in the crankcase somewhere to go when there is boost present in the intake. Preferably not back into the engine inlet. Straight vented covers work fine but I like running to a vented can to somewhat control the vapors from the breather filter.