Thread: any gains in porting the boost bypass passage?

Originally Posted by IndeedSS

Porting a gen 3 blower and LIM can be beneficial for those with an IC, but bypassing what gives you the power seems like it may have the opposite effect of what you are looking for. That said try out the BBV mod, and see what effects it has. If your car is like mine and it doesn't give you knock, then you will quickly find out the result of blocking off the BBV. Then you can figure the opposite may be true in opening it up further...

disclaimer: most of the time I don't know what I'm talking about...so experiment at your own risk.

Okay, let me ask something here, well maybe several somethings.

1. The BBV obviously Bypasses boost. Isnt that valve also open when you are not in boost? In other words, is it in the normal intake track channeling air to the motor and when you go into boost it closes off? If that is so, wouldnt opening that up allow more air flow for when the engine isnt in boost? Just thinking and questioning out loud here folks. I dont know what if any benefit it would be, just thinking.

2. If the BBV opening was ported, that would release boost faster, correct? How would this affect boost decel in the PCM and the possibility of flash KR? Though if you have let off the gas, I dont think this would matter much, but just something that crossed my mind.

3. How would this affect fueling. With the BBV not being either opened or close, rather it can be just about any where in between, how would this affect fueling?

1. I've only seen the BBV opened or closed, except the time before mine completely stuck open. Then it was bouncing up and down at idle. I assume it is either open or closed and doesn't operate at a partial position like your throttle blade does. What I do know is when the BBV is open (low load) the air goes through the BBV and the rotors. Under heavy load it is rotors only.

2. I don't see how it would release boost faster. I know what you are saying, but am not seeing it, I guess.

3. I never notice a change in KR or MPG. Assumption would be that more air would require more fuel.

I would love to here someones take, that builds performance engines, because I'm giving best guesses.