I still have the stock SC set-up as far as the kit-provided Bosch blow off valve, which vents back to the air filter, and the kit-provided crankcase vent hose, which is connected to the air filter. A lot of you guys have aftermarket BOVs which vent to the atmosphere instead of the air filter and a lot of you guys place a little filter directly on your crankcase instead of running a tube to the air filter.

What are the pros and cons to connecting the BOV and crank case vent hose to the air filter vs. the atmosphere?

 

i would not connect that hose to the crank case. that is supposed to be under 0 pressure. i like that the bosch can reroute the charge air to before the maf though. I think that if you are even thinking about going with the z32 maf, it would beneficial to keep it.

 

Steve, I don't know what you mean by 'that is supposed to be under zero pressure'.

So you say keep the stock Bosch BOV, huh?

Anyone else with some input? I know many people place little filters directly on the crank case and change out their Bosch BOVs. Just wondering why.

Thanks.

 

I have the crankcase filter and then routed the Greddy BOV back into my intake pipe. Mine is different than yours of course since the pipes are different

 

I am trying to understand why you guys place a little filter on the crankcase (vs. running a hose to the main air filter). Is there a performance advantage? Is it just for a cleaner look? Are there any negatives (ex. the air is hotter using a little filter)?

So what are the negatives to venting your BOV to the atmosphere vs. routing back into the intake? Positives?

Thanks.

 

depending on where the MAF is in the system (before or after the BOV), it can cause some issues with the car running rich during downshifts and off-throttle.

If you put the BOV after the MAF and then vent it to the atmosphere, then you're going to have extra fuel... the ECU expects the air to be in the cylinders, but it was vented to the atmosphere.

AFAIK, that's the only drawback to doing it that way.
the crankcase vents simply keep a bit of oil from blowing through the intake piping in the system and in theory increase emissions as the blowby is vented out that crankcase vent.

 

Putting a filter on the crankcase is just to prevent gunk from building up in the intake. Instead of the filter, an oil catch can will work too.

As for the BOV, if you want something simliar to the Bosch setup. Look into Vortech Bypass valve. You can route the air back into the air filter.