yes i was at that site before. but there are people saying its perfectly fine if its open at idle? is this true? will it have any negative effect on the car?

 

its supposed to be open at idle.


/thread

 

The spring determines how responsive the BOV is to changes in vacuum. Here's a breakdown

1. During boost the pressure is equal on both sides of the BOV (charge piping side and top portion of the valve)

2. A vacuum line is hooked into the top of the BOV, this is how pressure is equalized (boost pressure is also seen through vacuum ports, say from the intake manifold where most people reference their BOV line)

3. BUT, with the addition of the spring, the pressure keeping the valve closed (from the top) is boost pressure + whatever the rating of the spring is.

4. Because of the rating of the spring, the vacuum the engine pulls has to be enough to overcome the spring pressure for the characteristics of the BOV to match off throttle events. If the spring is too strong, the motor cannot open the valve on time, causing compressor surge. Too soft a spring will just keep it open whenever you're not in boost. Not much of a problem, except you're letting unfiltered air through the valve into the engine. I think it will adversely affect throttle response as well. Theorectically, you could use a 1psi spring and it would work

Hope that makes sense.

 

well i called tial. they said if vacuum at warmed up idle is between 20-22 i need an 11 pound spring, so Ijust ordered it.

thanks

 

Did the 11 psi spring keep it closed? Do you have any compressor surge? Didyou notice any quicker throttle reponse and quicker spool?

 

Did you actually measure Vacuum or were you going off of what they said at Tial? Not ever car reads the same Vacuum. Standard Hondas may run 20-22 but anything could change that. Are you stock motor? Are you low compression? Stock intake manifold and emissions devices? If you changed anything and have not checked what Vacuum your motor is actually pulling, just buying something someone told you might not be the right thing.

The BOV should slightly be open at idle, barely noticeable! Check your Vacuum first and then order. If you need a softer spring then just cut the heavier one!