ive been hearing many things from different people on the internet. they said that blow off valves that blow the air back into the intake are the best... ones that blow the air off into the atmosphere (engine bay) will cause drivability issues and will eventually damage your engine... is this theory true?

 

oh yeah, one more thing... i also heard that atmosphere BOV's leak boost... is this also true?

 

No and No. DSM guys have problems with venting to the atmosphere sometimes, honda guys don't. If you live in cali, you can't vent anything to the atmosphere, must go into the intake tract or the exhuast....

 

Thats only with cars with Mass Air Flow Meters....Cars that use speed density are alright(Map sensor)....Some DSM guys convert to speed density and you'll see that they vent to the atmosphere.

 

Exactly what he said. I had to vent the BOV back into the intake on my mustang because I was using a draw-thru MAF sensor, and if it didn't go back into the intake it would dump air that had already been accounted for by the computer and it would bog a little between shifts.